Location: MSHCP > VOLUME 2 > BIRDS
American bittern (Botaurus lentiginosus)
State: None
Federal: Species of Management Concern; Partners in Flight Priority Bird Species
The American bittern is sparsely-distributed throughout the MSHCP Plan Area within its suitable habitat, however, it is not predictably distributed within all suitable areas. It is found in margins surrounding open water bodies, and freshwater marshes where emergent vegetation is present. There are several likely Core Areas for this species based on past use by the American bittern or presence of suitable habitat, including Mystic Lake/San Jacinto Wildlife Area, Santa Ana River/Prado Basin, and Collier Marsh. The breeding locations (possibly at Mystic Lake/San Jacinto Wildlife Area [Garrett and Dunn 1980] and Santa Ana River/Prado Basin [L. Hays, pers. obs.]) which have been documented as active or possible are located at specific sites that require conservation. Because it is well known for using emergent habitat but has specific breeding location requirements, it is anticipated that this species will respond to a landscape level of management with site specific requirements.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 410 acres of suitable nesting and foraging habitat for the American bittern consisting of freshwater marsh.
Include within the MSHCP Conservation Area at least 3 Core Areas including Mystic Lake/San Jacinto Wildlife Area (Subunit 4 of RecheCanyon/Badlands Area Plan; 2,690 acres), a possible nesting area, Santa Ana River/Prado Basin (9,670 acres), a known nesting area, and Collier Marsh (Proposed Linkage 2; 160 acres), a potential nesting area, as well as other suitable habitat locations at Lake Skinner/Diamond Valley Lake (Existing Core J; 24,370 acres), Lake Mathews (Existing Core C; 15,610 acres), Vail Lake (Subunit 3 of Southwest Area Plan; 12,320 acres), Temescal Wash (Subunit 3 of Temescal Canyon Area Plan; 4,010 acres), and Temecula Creek (Subunit 2 of Southwest Area Plan; 850 acres).
A 100-meter buffer will be established around emergent vegetation areas identified in Objective 2 as they are incorporated into the MSHCP Conservation Area.
Within the MSHCP Conservation Area, maintain (once every 8 years) the continued use of 50 percent of the Core Areas.
The American bittern is virtually restricted to dense beds of cattails and rushes within freshwater and brackish water systems (Garrett and Dunn 1988). For the purpose of the conservation analysis, potential habitat for the American bittern includes freshwater marsh habitat. In addition, although not quantified, potential habitat includes the margins surrounding open water bodies that may contain desirable emergent plant communities suitable for foraging and nesting opportunities. Based on these habitats, the Plan Area supports approximately 470 acres of potential habitat for the American bittern. Table 1 shows the conservation and loss of potential habitat for the American bittern. Overall, approximately 410 acres ( 87 percent) of potential habitat in the Plan Area will be conserved in Criteria Area or existing Public/Quasi-Public Lands.
TABLE 1
SUMMARY OF HABITAT CONSERVATION FOR
AMERICAN BITTERN
| Vegetation Type | MSHCP Plan Area (Acres) |
Within MSHCP conservation Area | Outside MSHCP conservation Area | ||||
|---|---|---|---|---|---|---|---|
| Criteria Area1 (Acres) |
Public/ Quasi-Public (Acres) |
Total Within MSHCP Conservation Area (Acres) |
Rural/ Mountainous (Acres) |
Outside MSHCP Conservation Area (Acres) |
Total Outside MSHCP Conservation Area (Acres) |
||
| All Bioregions | |||||||
| Freshwater Marsh | 470 | 170 | 240 | 410 | 0 | 60 | 60 |
| TOTAL | 470 | 170 (36%) |
240 (51%) |
410 (87%) |
0 (0%) |
60 (13%) |
60 (13%) |
| 1 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. | |||||||
The Riparian/Riverine Areas and Vernal Pools policy described in Section 6.1.2 of the MSHCP, Volume 1, provides for conservation of wetlands and riparian values which will protect some habitat as well as important hydrologic functions for this species through avoidance and minimization. Mitigation for impacts to wetlands shall be incorporated in accordance with the "No Net Loss" policy of federal and state wetland regulations. The proposed mitigation shall be directly related to the functions and values of the wetland as related to this species and result in equivalent replacement.
As described below under Data Characterization, six of the eight recent point localities have a high location precision. Of these six point localities, all will be inside the Criteria Area or Public/Quasi-Public Lands. In addition, the one known nesting and one possible nesting location are within the Criteria Area or Public/Quasi-Public Lands. Also, the Core Area at Collier Marsh is within the Criteria Area or Public/Quasi-Public Lands. The other potential areas that contain suitable habitat, Lake Skinner (Existing Core J; 24370 acres), Lake Mathews (Existing Core C; 15610 acres), Vail Lake (Subunit 3 of Southwest Area Plan; 12,320 acres), Temescal Wash (Subunit 3 of Temescal Canyon Area Plan; 4,010 acres), and Temecula Creek (Subunit 2 of Southwest Area Plan; 850 acres), also are within the Criteria Area or Public/Quasi-Public Lands. Conservation of this species will be from a landscape perspective because the species is relatively difficult to detect yet has specific habitat requirements. Additionally, there are definable locations for focusing conservation efforts, and there are two important locations for breeding that are essential for conservation for the species.
Several areas of emergent habitat that contain the current known nesting locations, possible nesting locations, and potential foraging and nesting locations of the American bittern will be conserved in the Criteria Area and Public/Quasi-Public designations including the Prado Basin/Santa Ana River, Mystic Lake/San Jacinto Wildlife Area, Collier Marsh, Lake Skinner, Lake Mathews, Vail Lake, Temescal Wash, and Temecula Creek. Additionally, as these areas are incorporated into the MSHCP Conservation Area the margins surrounding these open water areas will be included in the MSHCP Conservation Area as well. As identified above, the species occurs within the MSHCP Plan Area predominantly as a transient or migrant and, as such, the MSHCP Conservation Area will provide adequate habitat for foraging during nomadic visits to the area and migratory stopovers as well as habitat containing potential nest sites with adequate protection around each nest site and foraging areas during the breeding season. Foraging areas are provided in suitable locations at Vail Lake, Lake Skinner, Mystic Lake/San Jacinto Wildlife Area, Collier Marsh, Lake Mathews, and Prado Basin/Santa Ana River. Potential and likely nest sites are provided in the Mystic Lake/San Jacinto Wildlife Area and known nesting areas are provided in the Prado Basin/Santa Ana River. These MSHCP Conservation Area areas are linked as well, however the American bittern, due to its ability to move long distances and nomadically, may rely less on the linkage than other species.
In summary, conservation for this species will be achieved by inclusion of at least 410 acres of suitable Conserved Habitat including freshwater marsh and the three Core Areas (including the two known or possible nest sites within the Prado Basin/Santa Ana River, Mystic Lake/San Jacinto Wildlife Area, and Collier Marsh) as well as the suitable locations at Lake Skinner, Lake Mathews, Vail Lake, Temescal Wash, and Temecula Creek. The current population size of the American bittern is unknown due to its very secretive nature.
About 60 acres (approximately 13 percent) of potential habitat for the American bittern will be outside the Criteria Area and Public/Quasi-Public areas and individuals within these areas will be subject to Incidental Take consistent with the Plan. Not-conserved habitat includes the margins surrounding Hemet Lake and Lake Riverside. Covered activities in these areas will be subject to the Protection of Species Associated with Riparian/Riverine Areas and Vernal Pools policy included in Section 6.1.2, Volume I of the MSHCP which calls for avoidance and minimization of impacts to wetlands.
Data reviewed includes the University of California, Riverside, GIS data base, the California Natural Diversity Data Base (CNDDB), and available literature.
The UCR location database contains a total of 18 records dated from 1900 to 1999. A total of eight of these records are recent, (within the past 10 years) and six of these recent records are precise records and could be accurately located within the Plan Area. The habitat types for these records include alkali playa, riparian, marsh, chaparral, and sage scrub, as well as one residential habitat record. This residential record may either no longer be extant or could have been located within a localized marsh within a residential development. Overall, the database records indicate that the American bittern is present within the Plan Area but in relatively low numbers.
The amount of literature available for the American bittern is relatively low. The species is secretive and located within a habitat within which it is difficult to conduct surveys and studies. The literature contains general biology information and some population studies and very little is available for the Plan Area other than general distribution studies.
American bitterns in California are found almost exclusively in emergent habitat of freshwater marshes and vegetated borders of ponds and lakes (Grinnell and Miller 1944). It may occur in sparsely vegetated wetlands occasionally and in tidal marshes rarely (Gibbs et al. 1992). It usually hides, rests, and roosts solitarily amidst tall, dense, emergent vegetation, on the ground, or near the ground on a log, stump, or on emergent plants. It does not normally perch in trees. It feeds in marshes, meadows, and along the edges of shallow ponds (Terres 1980). It also nests within emergent marshes within cattails, cordgrass, sedges, grasses, sedges of a wet meadow or marsh (Terres 1980). It will inhabit wetlands of all sizes but is more abundant on larger wetlands and may prefer impoundments and beaver-created wetlands to wetlands of glacial origin.
American bitterns breed locally from southeastern Alaska eastward to Newfoundland southward to southern California and Virginia; they have also bred (at least formerly) on the Mexican plateau. The species winters from British Columbia eastward to northern Florida south through (at least) Mexico and Cuba (AOU 1998).
The dependence on inland, freshwater marshlands suggests that this species may be a relict over much of the U.S. Historically, the range may have shifted northward, tracking the distribution of wetlands created by retreating glaciers. Breeding Bird Survey sighting frequencies indicate this species is more abundant in Canada than in the U.S., declining sharply below the northern border states. Thus it may be adapted primarily to northern climates and wetlands and now occurs sparsely in the U.S. over what represents the southern edge of its breeding range. Population declines in the U.S. may represent a hastening of an ongoing northern retreat by the species, in part because of habitat destruction in the southern portion of its range (Gibbs et al. 1992).
Zeiner. et al. (1990) describe the distribution, abundance, and seasonality as follows: the American bittern is distributed widely in winter in fresh emergent wetlands, primarily west of the Sierra Nevada. In the Central Valley, it is fairly common October to April, and uncommon to rare the rest of the year; although it breeds there. It is less common on the coastal slope, and no longer breeds regularly south of Monterey County (Garrett and Dunn 1981). In Imperial Valley and along Colorado River, it is fairly common October to April, rare through the summer, and may breed at the northern end of the Salton Sea. In the northeast plateau and east of the Sierra Nevada crest south to Lake Tahoe, it is rare from May to August; it breeds locally. It is rare August to May in saline emergent wetlands along the coast. Elsewhere in the lowlands, it is a rare transient and local winter resident (Cogswell 1977, McCaskie, et al. 1979, Garrett and Dunn 1981). Within coastal southern California, the species is primarily a winter visitor, with nesting occurring only rarely in the coastal plain (Garrett and Dunn 1981).
The small breeding population in the lowlands may be nonmigratory; it may be augmented during October to April by migrants, probably from north of California and from the northeastern plateau, which is deserted in winter by this species (Zeiner, et al. 1990).
Although American bitterns have been repeatedly recorded in the San Jacinto Wildlife Area/Mystic Lake area and it possibly breeds there (Garrett and Dunn 1981) the only known breeding location is at the Prado Basin (L. Hays, pers. comm.).
Geographic locations recorded within the U.C. Riverside database include: Temecula Creek, Temescal Wash, Lake Mathews, Santa Ana River/Prado Basin, Lake Elsinore, Lake Perris, and Mystic Lake/San Jacinto Wildlife Area. These records do not confirm breeding locations but the habitat is present and breeding could occur in these regions or the area may be used for foraging. American bitterns are secretive birds and may escape detection in the absence of relatively intensive, focused surveys.
Genetics: The American bittern is the smallest of the four species of Botaurus bitterns. Within the genus, the American bittern and south American bittern differ sufficiently in skeletal characteristics from one another and from the old world bitterns to be considered separate species (Gibbs et al. 1992). The species is monotypic and available data do not support the subspecific differentiation of birds from the eastern versus western North America (Gibbs et al. 1992).
Diet and Foraging: The American bittern forages within the emergent vegetation and shallow water of fresh or saline wetlands (Zeiner, et al. 1990). It feeds less often in adjacent shallow water of lakes, backwaters of rivers, or estuaries; and occasionally along adjacent shores. It feeds most actively at dusk or at night (Terres 1980), but also apparently at any time of day. It stands motionless and waits for prey, or stalks very slowly; it grasps the prey in the bill with a quick strike (Kushlan 1976b). It eats mainly insects, amphibians, fish, crayfish, and small mammals; also snakes, miscellaneous invertebrates, and birds.
Daily Activity: The American bittern is a year-long, circadian feeder, but most activity is crepuscular and nocturnal (Zeiner, et al. 1990).
Reproduction: The nest of the American bittern is a platform of matted, emergent aquatics, other herbaceous stems, sticks and/or leaves, usually in shallow water, but sometimes floating, or on the ground. It nests within the emergent vegetation and shallow water of fresh or saline wetlands (Zeiner, et al. 1990). Within the Prado Basin, the birds possibly breed in ponds with substantial tule/bulrush cover (L. Hays, USFWS, pers. obs.). The timing of courtship and nest-building is unknown; eggs or young have been reported April to July (Cogswell 1977). It is possibly polygamous, based on minimal evidence. It is basically a solitary nester, but is often in the vicinity of other pairs. The clutch size is usually 3-5 eggs, with a range of 2-6 eggs. It is apparently single-brooded. Incubation is about 24 days. The semi-altricial, downy hatchlings are apparently tended solely by the female, and remain in the nest about two weeks.
Survival: Little information is available. One banded individual of the American bittern lived at least 8 years (Gibbs et al. 1992).
Dispersal: Ages at first flight, independence, and first breeding of the American bittern are unknown (Palmer 1962). The American bittern is thought to undergo extensive, postbreeding dispersal which may account for the number of sightings, mostly in September through December in locations as distant as Iceland, Norway and Great Britain (Gibbs et al. 1992).
Socio-Spatial Behavior: In a slough in Saskatchewan, less than 16 hectares (40 acres) in extent, there were five nests of the American bittern (Bent 1926). Distances between nests have been as little as 18 meters (57 feet) in Michigan (Middleton 1949), 37 meters (120 feet) in lowa (Provost 1947), and 46 meters (150 feet) in Minnesota (Vesall 1940). The territory is probably used mainly for courtship, copulation, and nesting; size is unknown (Palmer 1962).
Community Relationships: No information is available within the literature.
American bitterns apparently historically were more common and widespread in coastal southern California (Garrett and Dunn 1981). As early as the 1940's, Grinnell and Miller (1944) noted that the "extent of distribution and numbers have been diminishing concurrently with the effacement of appropriate habitat." The population has declined due to the draining of marshes, human disturbance, and pesticides. Overgrazing of emergent vegetation also is detrimental to the species. (Arbib 1979).
American bitterns have been known to nest within restored bulrush marsh areas, a floodwater storage pool and even various kinds of upland vegetation, although this is rare (Svedarsky 1992). The species may also make use of wetlands created by surface mining (Perkins and Lawrence 1985).
Habitat degradation is also a factor in causing changes in the population size of the American bittern. Eutrophication, siltation, chemical contamination, and human disturbance may seriously reduce habitat quality, primarily by damaging the prey supplies. Changes in wetland isolation and stabilized water regimes may seriously erode habitat quality for bitterns (Gibbs et al. 1992).
Preservation of freshwater wetland habitats, particularly large (greater than 10 hectares) shallow wetlands with dense growths of robust emergents is the most urgent management need. Wetlands used for breeding by American bitterns also need to be protected from chemical contamination, siltation, eutrophication, and other forms of pollution that harm the birds or their food supplies (Gibbs et al. 1992).
Arbib, R. 1979. The blue list for 1980. American Birds 33: 830-835.
AOU (American Ornithologists' Union). 1998. Check-List of North American Birds. Seventh Edition. American Ornithologists' Union, Washington, D.C. 829 pp.
Bent, A. C. 1926. Life histories of North American marsh birds. U.S. Natl. Mus. Bull. 135. 490pp.
Cogswell, H. L. 1977. Water birds of California. Univ. California Press. Berkeley 399 pp.
Garrett, K. and J. Dunn. 1981. Birds of Southern California: Status and Distribution. Los Angeles Audubon Society. 407 pp.
Gibbs, J.P., S. Melvin, and F. A. Reid. 1992. American Bittern. The Birds of North America 18: 1-12.
Grinnell, J. and A.H. Miller. 1944. The Distribution of the Birds of California. Pacific Coast Avifauna Number 27. Copper Ornithological Club, Berkeley, California. Reprinted by Artemisia Press, Lee Vining, California; April, 1986. 617 pp.
Kushlan, J. A. 1976b. Wading bird predation in a seasonally fluctuating pond. Auk 93:464- 476.
McCaskie, G., P. De Benedictis, R. Erickson, and J. Morlan. 1979. Birds of northern California, an annotated field list. 2nd ed. Golden Gate Audubon Soc., Berkeley. 84pp.
Middleton, D. S. 1949. Close proximity of two nests of American bitterns. Wilson Bull. 61:113.
Palmer, R. S., ed. 1962. Handbook of North American birds. Vol. 1. Yale University Press, New Haven, CT. 567pp.
Perkins, G. A. And J. S. Lawrence. 1985. Bird use of wetlands created by surface mining. Trans. Ill. State Acad. Sci. 78: 87-96.
Provost, M. W. 1947. Nesting of birds in the marshes of northwest Iowa. Am. Midl. Nat. 38:485-503.
Sverdarsky, W. D. 1992. Observations on nesting of the American bittern in northwest Minnesota. Prairie Naturalist 24: 241-250.
Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. A. Knopf, New York. 1100pp.
Vesall, D. B. 1940. Notes on nesting habits of the American bittern. Wilson Bull. 52:207- 208.
Zeiner, D. C., W., F. Laudenslayer, Jr., K. E. Mayer, M. White. Editors. 1990. California's Wildlife. Volume 2. Birds. State of California, Department of Fish and Game. Sacramento, California. 731 pp.
bald eagle (Haliaeetus leucocephalus)
State: Endangered; Fully-Protected Species; California Department of Forestry and Fire Prevention Sensitive
Federal: Threatened (Federal Register 60:36010, July 12, 1995); Partners in Flight Priority Bird Species; Bald Eagle Protection Act of 1940
The bald eagle was initially listed on February 14, 1978 as an endangered species throughout the lower 48 states, except in Minnesota, Michigan, Wisconsin, Washington, and Oregon, where it was listed as a threatened species. On July 12, 1995, the USFWS announced that the bald eagle would be reclassified from endangered to threatened in the lower 48 states, effective August 11, 1995. In those states where the species was already listed as threatened, it remains classified that way but was proposed for delisting in July 1999.
The bald eagle has a wide distribution throughout the MSHCP Plan Area within its suitable habitat. It occurs or has occurred at every open water body within the Plan Area. It uses suitable habitat predictably and responds well to available suitable habitat. It occurs within the Plan Area predominantly as a winter visitor with casual occurrences in the summer of individuals that have lingered at the wintering sites. It has attempted to breed at Lake Elsinore and at Lake Skinner but has not done so successfully.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 10,340 acres of open water habitat at the following seven open water bodies and one drainage: Lake Mathews, Diamond Valley Lake, Lake Skinner, Lake Elsinore, Vail lake, Lake Perris, Mystic Lake and Santa Ana River. Include within the MSHCP Conservation Area 5,520 acres of suitable riparian habitat within the Prado Basin and Santa Ana River.
A 100-meter buffer will be established around open water bodies identified in Objective 1 as they are incorporated into the MSHCP Conservation Area.
For the purpose of the conservation analysis, potential habitat for the bald eagle includes open water lakes and reservoirs, a shoreline buffer of 100 meters around each of the open water lakes and reservoirs, and the riparian habitat within the Prado Basin and Santa Ana River. Although the bald eagle has not recently bred successfully within the MSHCP Plan Area, potential breeding habitat does occur around several of the water bodies. Based on these habitats, the Plan Area supports approximately 18,000 acres of potential habitat for the bald eagle. Table 1 shows the conservation and loss of potential habitat for the bald eagle. Overall, approximately 15,860 acres (88 percent) of potential habitat in the Plan Area will be conserved in Criteria Area or existing Public/Quasi-Public lands.
As described below under Data Characterization, 8 of the 17 recent point localities have a high location precision. Of these eight point localities, three will be inside the Criteria Area or Public/Quasi-Public Lands. However, of the five points located outside these habitat areas, all are mapped in existing residential/urban/exotic areas or in existing agriculture or other upland habitats. These habitats do not constitute suitable habitat but these locations may have been of a bird flying overhead or within habitat adjacent to one of the reservoirs. Conservation of this species is being considered from a landscape perspective because the species is found throughout the Plan Area and is well documented for the type of habitat within which they forage. While there are definable locations for focusing conservation efforts, these do not constitute Core Areas. Any nesting locations identified will be important to preserve.
TABLE 1
SUMMARY OF HABITAT CONSERVATION
BALD EAGLE
| Vegetation Type | MSHCP Plan Area (Acres) |
Within MSHCP conservation Area | Outside MSHCP conservation Area | ||||
|---|---|---|---|---|---|---|---|
| Criteria Area1 (Acres) |
Public/ Quasi-Public (Acres) |
Total Within MSHCP Conservation Area (Acres) |
Rural/ Mountainous (Acres) |
Outside MSHCP Conservation Area (Acres) |
Total Outside MSHCP Conservation Area (Acres) |
||
| All Bioregions | |||||||
| Open Water | 12,210 | 1,190 | 9,150 | 10,340 | 40 | 1,830 | 1,870 |
| Riparian Habitat within Prado Basin/Santa Ana River | 5,790 | 510 | 5,010 | 5,520 | 0 | 270 | 270 |
| TOTAL | 18,000 | 1,700 (9%) |
14,160 (79%) |
15,860 (88%) |
40 (<1%) |
2,100 (12%) |
2,140 (12%) |
| 1 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. | |||||||
Several large blocks of habitat supporting the current known locations and potential foraging and nesting locations of the bald eagle will be conserved as Criteria Area and Public/Quasi-Public designations, including the Prado Basin, Santa Ana River, Lake Skinner, Diamond Valley Lake, Lake Mathews, Lake Perris, Mystic Lake, Lake Elsinore, and Vail Lake. The MSHCP Conservation Area will provide adequate habitat for foraging during winter, nomadic visits to the area, and migratory stopovers. The MSHCP Conservation Area will also provide potential nest sites and foraging areas during the breeding season. Foraging areas are provided at Vail Lake, Lake Skinner, Diamond Valley Lake, Lake Perris, Mystic Lake, Lake Elsinore, Lake Mathews, Prado Basin and Santa Ana River. Potential perching and nest sites are provided at these open water/reservoir areas in the form of large trees or snags within the 100 meter wide buffer around each water body. The bald eagle, due to its ability to move long distances, will rely less on the linkages between potential breeding areas than other species.
In summary, conservation for this species will be achieved by inclusion of at least 15,860 acres of suitable Conserved Habitat including open water bodies and riparian habitat within the Santa Ana River and Prado Basin. The current population size of the bald eagle is unknown because it is primarily a winter and transient visitor. However, a single pair has made repeated, but unsuccessful, attempts to breed at Lake Skinner in recent years.
The estimated Take of the bald eagle is based on the acreage of potentially suitable and/or occupied habitat. About 2,140 acres (12 percent) of potential habitat for the bald eagle will be outside the Criteria Area and Public/Quasi-Public designations and individuals within these areas will be subject to Incidental Take consistent with the Plan. Potential habitat not included within the MSHCP Conservation Area includes the open water habitat at Hemet Lake and Lake Riverside.
Data reviewed includes the University of California, Riverside, GIS data base, the California Natural Diversity Data Base (CNDDB), and available literature.
The UCR location database for the bald eagle includes a total of 31 records dated from 1973 to 1999. All but one of these records is from local biologists reports; a survey conducted in 1996 by the USFWS reported one location record. A total of 17 of these records are relatively recent (within the past 10 years) and of these recent records, a total of 8 are of high precision. The habitats with which these records are associated includes grassland, chaparral, riparian, croplands, residential, and open water. The upland and residential habitat location records probably reflect observations of a bald eagle in flight over an area.
The literature available on the bald eagle is fairly extensive for a number of reasons, not the least of which is the fact that the bald eagle is our Nation's symbol. It has been studied for many years by ornithologists interested in raptors. Due to its listed status, the pesticide problems to which were attributed its population decline a number of years ago, as well as the interest in its recovery from its population decline, a large number of natural history articles as well as summary information within the general ornithological literature is available. Little information is available that pertains directly to the Plan Area other than general distribution information.
Range-wide, bald eagles occur primarily at or near seacoasts, rivers, swamps, and large lakes (AOU 1998). It is considered a bird of aquatic ecosystems but within such areas, it must have an adequate food base, perching areas, and nesting sites to support them (Gerrard and Bortolotti 1988). Perching sites need to be composed of large trees or snags with heavy limbs or broken tops (USFS pers. comm. 1999). The bald eagle nests in trees, rarely on cliff faces and ground nests in treeless areas and always relatively close to water with suitable foraging opportunities. The actual distance to water varies within and among populations of the bald eagle. In some cases, the distance to water is not as critical as the quality of the foraging area. The quality of the foraging areas is defined by the diversity, abundance, and vulnerability of the prey base, the structure of aquatic habitat such as the presence of shallow water and absence of human development and disturbance (Buehler 2000). The diurnal perch habitat is characterized by presence of tall, easily accessible, often super-canopy trees adjacent to the shoreline foraging habitat. The perch tree species used by the bald eagle are highly variable, including both coniferous and deciduous species if present. Most perch trees are live trees although dead trees may be preferred if available. The bald eagle selects a wider range of tree species and sizes for perching than for nesting or roosting (Buehler 2000).
Within southern California, although birds are found in these same habitats, they are most often recorded at large deep inland bodies of water and are considered a winter resident that in the past may have bred in the area (Garrett and Dunn 1981). In winter, bald eagles often congregate at specific wintering sites that are generally close to open water and that offer good perch trees and night roosts. The bald eagle may roost communally in winter in dense, sheltered, remote conifer stands (Zeiner, et al. 1990). In Klamath National Forest, winter roosts were 16-19 kilometers (10-12 miles) from feeding areas (Spencer 1976). The bald eagle often concentrates in large numbers on the wintering grounds. The winter habitat suitability is defined by the food availability, the presence of roost sites that provide protection from inclement weather and absence of human disturbance although bald eagles will tolerate some human activity in areas of high prey availability. The perching habitat during the wintering season is characterized by the presence of tall trees located adjacent to foraging areas similar to other times of the year (Buehler 2000).
The bald eagle is the only sea eagle regularly occurring on the North American continent. Bald eagles breed locally from Alaska eastward to Newfoundland southward locally to Baja California, Sonora, Texas, and Florida. The species winters in the large majority of the breeding range but generally withdraws from central Alaska and the central and the northern portions of Canada (AOU 1998). Individuals that breed in California may make only local winter movements in search of food.
Within mainland southern California, the species primarily winters at larger bodies of water in the lowlands and mountains (Garrett and Dunn 1981). It is fairly common as a local winter migrant at a few favored inland waters in southern California. Largest numbers occur at Big Bear Lake, Cachuma Lake, Lake Mathews, Nacimiento Reservoir, San Antonio Reservoir, and along the Colorado River (Zeiner et al. 1990). Recent breeding attempts on the mainland south of Santa Barbara County (e.g., Silverwood Lake, Lake Skinner, Lake Perris) have been unsuccessful (K. Cleary-Rose, pers. comm., 2002).
The historic breeding range of the bald eagle is probably similar to the present breeding distribution with major changes, both losses and gains of breeding areas in the twentieth century. The distribution reported by Oberholser (1906) is very similar to the present distribution (Buehler 2000).
Notwithstanding failed nesting attempts (see "Current Range" above) by summering or resident birds, the bald eagle is primarily a migrant and wintering species within western Riverside County. Although the species remains nowhere common and is generally rare and local in southern California (Garrett and Dunn 1981), the species could turn up virtually anywhere within western Riverside County in suitable habitats and may, in fact, attempt to nest. Thus, as a species occurring within the area in the summer, it is considered a casual occurrence. Generally, however, it is considered a very localized winter visitor that is fairly common at a few favored wintering sites around inland bodies of water yet is generally very rare otherwise (Garrett and Dunn 1981).
Birds have been detected in recent years at the Prado Basin, Lake Skinner, Lake Mathews, and Lake Perris. There are also records from Lake Elsinore, where the species may have bred in the past (Garrett and Dunn 1981), and the species has been observed infrequently at Lake Hemet and Vail Lake. Recently, the bald eagle has attempted to breed at Lake Skinner. Up to 20 eagles were reported to be present at Lake Mathews (Garrett and Dunn 1981).
Genetics: There are eight species in the genus Haliaeetus which are distributed worldwide except in South America. The genus is most closely related to the other fish eagles and is perhaps also related to the scavenging kites and to the Old World vultures. The bald eagle is likely most closely related to and may constitute a superspecies with the white-tailed eagle (H. Albicilla) (Buehler 2000).
Diet and Foraging: Fish predominate the typical diet of bald eagles, however, many other types of prey are also taken, including waterfowl and small mammals, and carrion especially in the wintering areas (USFWS 1995). It swoops from hunting perches, or soaring flight to pluck fish from water. It is also known to wade into shallow water to pursue fish. It may pounce on, or chase, injured or ice-bound water birds. In flooded fields, the species occasionally pounces on displaced voles, or other small mammals. Open, easily approached hunting perches and feeding areas are used most frequently (Zeiner, et al. 1990). Bald eagles tend to hunt cooperatively (Brown 1999). Studies of prey items in northern California, showed bald eagles do not differentiate between native and non-native freshwater fish species (Jackman, et al. 1999). One study of birds in Texas found them to eat a relatively equal proportion of birds, reptiles and fish (Mabie, et al. 1995). One wintering population in the lower Great Lakes basin was observed feeding on carcasses of white-tailed deer during 47 percent of observed feedings (Ewins and Andress 1995). The same group observed immature individuals feeding on garbage and offal 39 percent of feedings.
Daily Activity: Wintering bald eagles in New Mexico spent 95.3 percent of their time perched and 4.7 percent in flight (Zwank, et al. 1996). Of the time spent in flight, 13.0 percent was spent foraging (Zwank, et al. 1996). Winter feeding usually occurs immediately after dawn and in late afternoon (Zeiner, et al. 1990).
Reproduction: Breeding of the bald eagle occurs in open areas, near water, with nests often in large snags or old-growth trees (Brown 1999). The bald eagle also nests in a dominant live tree with open branch work, especially ponderosa pine. It nests most frequently in stands with less than 40 percent canopy, but there is usually some foliage shading the nest (Call 1978). It often chooses the largest tree in a stand on which to build its stick platform nest. The nest may be a massive structure, twelve feet high, eight and a half feet across and with a wet mass of decaying vegetation in the center, weighing many hundred pounds (Brown and Amadon 1968). The nest is typically located 16-61 meters (50-200 ft) above ground, usually below the tree crown. The species of tree that is used for locating the nest site is apparently not so important as the height and size. The nest is usually located near a permanent water source. In California, 87 percent of the nest sites of the bald eagle were within 1.6 kilometers (1 mile) of water. Individuals have been known to use the same nest for up to 35 years (Brown 1999).
The clutch size of the bald eagle is usually two, but can vary from one to three, and eggs are laid once annually (Brown 1999). The bald eagle breeds from February through July, with a peak in activity from March to June. Incubation of the eggs usually lasts 34-36 days. The semi-altricial young hatch asynchronously (Ehrlich, et al. 1988). The species is monogamous, and breeds first at 4-5 years (Zeiner, et al. 1990).
Survival: In one study of bald eagle nests in British Colombia, Canada, food supply was identified as the "key factor" in limiting breeding success (Elliot, et al. 1998). Because of the asynchronous hatching the older nestling may kill the younger, smaller sibling if the food supply is inadequate (Brown and Amadon 1968). The recorded longevity in the wild is 28 years and 36 years in captivity. Bald eagles may follow the survival pattern similar to other raptors with lower first-year survival followed by increasing survival to adulthood. Adult survival is high in most studies on survivorship (Buehler 2000).
Dispersal: The young of the bald eagle leave the nest 70 to 98 days after hatching but do not reach breeding age until four or five (Brown 1999). A mark-recapture study of a breeding population in Texas concluded that birds fledged there may disperse to breeding communities throughout the southern United States (Mabie, et al. 1994).
Socio-Spatial Behavior: The bald eagle home range of resident pairs on the Columbia River averaged 22 km2 for both breeding and non-breeding periods (Garrett, et al. 1993). The breeding territory in Alaska (n= 14), varied from 11-45 hectares (28-112 acres), and averaged 23 hectares (57 acres) (Hensel and Troyer 1964). The breeding territory is defended from the mating through the fledging period of the pair. Minimum distances between bald eagle nests were 1 kilometer (0.6 miles) in Alaska, and 17 kilometers (10 miles) in Washington (Zeiner, et al. 1990).
Community Relationships: The bald eagle competes with, and steals prey from osprey (Zeiner, et al. 1990). It has been observed causing a turkey vulture to disgorge its food (Brown and Amadon 1968).
Habitat loss, the expressed effects of select pesticides on reproductive success, and persecution of the species necessitated the listing of the bald eagle. The use of DDT after World War II led to eggshell thinning which drastically reduced reproductive success and the species' populations (USFWS 1995). The species does not occupy its former breeding range in southern California or occur in numbers comparable to historical totals (Grinnell and Miller 1944 and Garrett and Dunn 1981). However, successful captive breeding efforts, the banning of certain organochlorine pesticides, and other recovery efforts have resulted in apparent, significant increases in eagle numbers on the continent. Special pressures on individuals in the southwestern United States include: heat stress, nest parasites and entanglement in fishing line debris from intense fishing pressure (USFWS 1995).
A study of nests in Oregon identified the following causes of nest failures: pesticides (32 percent), proximity to nearest-neighbor breeding pairs (11 percent), infertile eggs (7 percent), nestling mortality (3 percent), human disturbance (2 percent), changes in members of a pair (1 percent), and unknown causes (21 percent) (Anthony, et al. 1994).
Human recreational use of reservoirs and rivers occupied by bald eagles has been greatly studied (Stalmaster and Kaiser 1998). Territories have been abandoned after there has been disturbance from logging, recreational development, and other human activities near nests of the bald eagle (Thelander 1973). In northwest Washington, feeding activity was found to decline exponentially with increased recreational activity (Stalmaster and Kaiser 1998). Foot traffic caused the greatest flushing distance but boat activities accounted for a greater proportion of the disturbances (Stalmaster and Kaiser 1998).
Bald eagles are sensitive to human encroachment and disturbance. Currently, over one million dollars in public and private money is spent each year toward recovery and protection of bald eagle populations (USFWS 1995). These efforts have increased populations from 417 active nests in the lower 48 states in 1963, according to the National Audubon Society, to 4,450 in 1994 (USFWS 1995).
Researchers recommended that recreational activity during the breeding season be restricted during the first five hours of sunlight where bald eagles are present (Stalmaster and Kaiser 1998). Another study in Arizona found 22-times more eagles nesting in areas with low human use compared to areas with moderate or high human use (Brown and Stevens 1997).
The variable effects of human activity on the reproductive performance of bald eagles implies a threshold for detrimental impact between pristine isolation and outright destruction. Management concepts to protect nesting bald eagles have evolved from concentric-circles buffer zones at nest sites through single territory zonation to a multiple territory regional approach (Grubb and King 1991). Additional research has concluded that management of potentially disturbing human activity near breeding bald eagles should be based on multivariate considerations of action and reaction (Grubb and King 1991). Distance to disturbance is the most important aspect of human disturbance. Human activities that are distant, of short duration, out of sight, few in number, below, and quiet have the least impact. Despite the multi-dimensional nature of human disturbance, any category of disturbance can, in excess or under the proper circumstances, disrupt normal behavior or cause nesting failure. Importance of disturbance groups varies with their associated characteristics. This study suggests a minimum, generic, primary zone of approximately 600 meters around breeding bald eagles (Grubb and King 1991). A 1,200-meter secondary buffer zone would accommodate most of the distant responses from vehicle, noise, and aircraft disturbance. Typically, no human activity is permitted at any time within a primary protection zone. Within a secondary buffer zone, limited, nonpermanent activity may be allowed during the non-breeding season. Other buffer distances of similar magnitudes have been suggested by other researchers for breeding bald eagles (summarized in Grubb and King 1991). This study has provided additional specific distances based on the general category of the disturbance. These values will be useful for management purposes in the event that the bald eagles located within the western Riverside County area attempt to breed. The management recommendations from Grubb and King (1991) for buffer distances for specific activities in association with breeding bald eagles are as follows: Pedestrian disturbance - complete restriction at 543 meters; aquatic disturbance - restriction at 200 meters; vehicle disturbance - complete restriction at 450 meters and limited vehicular control at 850 meters; noise disturbance (includes gunshot and sonic booms) - restrictions within 1,000 meters but may need extending up to 2,000 meters; aircraft disturbance - exclusion within 625 meters and limited flights within 1,100 meters.
The bald eagle was one of four wintering raptor species shown to be sensitive to urbanization, having a threshold of approximately five to seven percent urbanization (Berry, et al. 1998). A group of researchers have used perch tree abundance and shoreline development measures to accurately predict numbers of bald eagles (Chandler, et al.1995).
Human disturbance activities may elicit various responses from wildlife and differences in persecution histories result in diverse wildlife responses to different activity types. The bald eagle is more likely to flush when approached by a human on foot than when approached by an automobile (Holmes et al. 1993). That a person approaching in plain view of a raptor elicits a stronger response than a person within an approaching vehicle suggests that humans approaching slowly are viewed as a greater disturbance than vehicles, which are moving rapidly and screen humans. Some bald eagles have demonstrated habituation to human presence. Wintering bald eagles show lower flushing responses along rivers and estuaries with high levels of recreational boating activity than along adjacent areas with little boating activity (Holmes et al. 1993). However these studies did not monitor the effects of the human disturbances on the reproductive success. Spatial buffer zones are commonly used to protect nesting sites from disturbance, however, buffer zones for wintering raptors also could be effective if placed around sensitive foraging areas. From this study, a buffer zone that would prevent flushing by approximately 90 percent of the wintering individuals of the golden eagle would be set at 300 meters (Holmes et al. 1993). Although this study did not specify the bald eagle and studies were not conducted for bald eagles, presumably the buffer distance for wintering bald eagles might be set for at least as great as the golden eagle until further research determines a different distance is more beneficial.
Because of the selectivity of roost sites by bald eagles (roost trees have greater diameter at breast height, more branching structure and are generally taller than randomly sampled trees) forest harvests should be conducted through selective thinning, prescribed fire and seeding with roost-like trees (Dellasala, et al. 1998).
AOU (American Ornithologists' Union). 1998. Check-List of North American Birds. Seventh Edition. American Ornithologists' Union, Washington, D.C. 829 pp.
Anthony, R. G., R. W. Frenzel, F. B. Isaacs and M. G. Garrett. 1994. Probable causes of nesting failures in Oregon's bald eagle population. Wildlife Society Bulletin 2:576-582.
Berry, M. E., C. E. Bock and S. L. Haire. 1998. Abundance of diurnal raptors on open space grasslands in an urbanized landscape. Condor 100: 601-608.
Brown, B. T. and L. E. Stevens. 1997. Winter bald eagle distribution is inversely correlated with human activity along the Colorado River, Arizona. Journal of Raptor Research 31:7-10.
Brown, N. L. 1999. World Wide Web-site: http://arnica.csustan.edu/esrpp/baldeg.htm.
Brown, L., and D. Amadon. 1968. Eagles, hawks and falcons of the world. 2 Vols. Country Life Books, London. 945pp.
Buehler, D. A. 2000. Bald Eagle (Haliaeetus leucocephalus). Number 506. In The Birds of North America, A. Poole and F. Gill, Eds. Cornell Laboratory of Ornithology and The Academy of Natural Sciences, Washington D.C.
Call, M. W. 1978. Nesting habits and survey techniques for common western raptors. U. S. Dep. Inter., Bur. Land Manage., Portland, OR. Tech. Note No. 316. 115pp.
Chandler, S. K., J.D. Fraser, D. A. Buehler and J. K. D. Seegar. 1995. Perch trees and shoreline development as predictors of bald eagle distribution on Chesapeake Bay. Journal of Wildlife Management 59:325-332.
Cleary-Rose, K. 2002. Pers. comm. U.S. Fish and Wildlife Service.
Dellasala, D. A., R. G. Anthony, T. A. Spies and K. A. Engel. 1998. Management of bald eagle communal roosts in fire-adapted mixed-conifer forests. Journal of Wildlife Management 62:322-333.
Elliot, J. E., I. E. Moul, K. M. Cheng. 1998. Variable reproductive success of bald eagles on the British Columbia coast. Journal of Wildlife Management 62:518-529.
Ewins, P.J. and R. A. Andress. 1995. The diet of bald eagles, Haliaeetus leucocephalus, wintering in the lower Great Lakes Basin, 1987-1995. Canadian Field-Naturalist 109:418-425.
Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's handbook. Simon and Schuster, New York. 785pp.
Garrett, K. and J. Dunn. 1981. Birds of Southern California: Status and Distribution. Los Angeles Audubon Society. 407 pp.
Garrett, M G., J. W. Watson and R. G. Anthony. 1993. Bald Eagle Home Range and Habitat use in the Columbia River Estuary. Journal of Wildlife Management 57:19-27.
Gerrard and Bortolotti. 1988. The bald eagle: haunts and habits of a wilderness monarch. Smithsonian Inst. Press, Washington, 177pp.
Grinnell, J. and A.H. Miller. 1944. The Distribution of the Birds of California. Pacific Coast Avifauna Number 27. Copper Ornithological Club, Berkeley, California. Reprinted by Artemisia Press, Lee Vining, California; April, 1986. 617 pp.
Grubb, T. G. and R. M. King. 1991. Assessing human disturbance of breeding bald eagles with classification tree models. J. Wildl. Management 55: 500-511.
Hensel, R. J., and W. A. Troyer. 1964. Nesting studies of the bald eagle in Alaska. Condor 66:282-286.
Holmes, T., R. L. Knight, and G. R. Craig. 1993. Responses of wintering grassland raptors to human disturbance. Wildlife Society Bulletin 21: 461-468.
Jackman, R. E., W. G. Hunt, J. M. Jenkins and P. J. Detrich. 1999. Prey of nesting Bald Eagles in northern California. Journal of Raptor Research 33:87-96.
Mabie, D. W., M. T. Merendino and D. H. Reid. 1995. Prey of nesting bald eagles in Texas. Journal of Raptor Research 29:10-14.
Mabie, D. W., M. T. Merendino and D. H. Reid. 1994. Dispersal of Bald Eagles Fledged in Texas. Journal of Raptor Research 28: 213-219.
Oberholser, H. C. 1906. The North American eagles and their economic relations. U.S. Dept. Agriculture Biol. Surv. Bull. 27, Washington, D. C.
Spencer, D. A., ed. 1976. Wintering of the migrant bald eagle in the lower 48 states. Natl. Agric. Chem. Assoc. Publ., Wash. DC. 170pp.
Stahlmaster, M.V. and J. L. Kaiser. 1998. Effects of recreational activity on wintering bald eagles. Wildlife Monographs 137: 1-46.
Thelander, C. G. 1973. Bald eagle reproduction in California, 1972-1973. Calif. Dept. Fish and Game, Sacramento. Wildl. Manage. Branch Admin. Rep. 73-5. 17pp.
United States Fish and Wildlife Service. 1995. Endangered and Threatened Wildlife and Plants; Final Rule to Reclassify the Bald Eagle from Endangered to Threatened in all of the Lower 48. Federal Register 50 CFR Part 17, v.60, n.133 July 12, 1995:35999-36010.
United States Forest Service (USFS). 1999. Pers. comm. Species accounts for threatened, endangered and sensitive wildlife species occurring in the San Bernardino National Forest.
Zeiner, D. C., W., F. Laudenslayer, Jr., K. E. Mayer, M. White. Editors. 1990. California's Wildlife. Volume 2. Birds. State of California, Department of Fish and Game. Sacramento, California. 731 pp.
Zwank, P.J., B. L. Tarrant, R. Valdez and D. L. Clason. 1996. Wintering bald eagle populations and behavior in the middle Rio Grande Basin, New Mexico. Southwestern Naturalist 41:149-154.
Bell's sage sparrow (Amphispiza belli belli)
State: Species of Special Concern
Federal: Partners in Flight Priority Bird Species; Species of Management Concern; Federal Special Concern species
Other: Audubon Society California Watch List
The Bell's sage sparrow is widely but sparsely distributed throughout the MSHCP Plan Area within suitable habitat in the Riverside lowlands, Santa Ana Mountains, Desert Transition and San Jacinto Foothills Bioregions. It is absent from higher elevation Bioregions. The Bell's sage sparrow occurs within several areas that appear to be Core Areas including Jurupa Mountains, Lake Mathews-Estelle Mountain, Wasson Canyon, Santa Rosa Plateau, Sedco Hills, Hogbacks, Lake Skinner/Diamond Valley Lake, Vail Lake/Wilson Valley/Aguanga, Tule Valley, Santa Rosa Hills, Lakeview Mountains, Lake Perris, Badlands, and Box Springs Mountains. However, none of these Core Areas contains large or dense populations of the Bell's sage sparrow. The Bell's sage sparrow is a year-round resident within the Plan Area. Because it is well known for using coastal sage scrub and chaparral habitats, occurs widely but sparsely and well scattered within these habitats in the Riverside lowlands, San Jacinto Foothills, Desert Transition, and Santa Ana Mountains Bioregions, but has specific locations that are Core Areas, it is anticipated that this species will respond well to a landscape level of management with site specific requirements.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 245,750 acres of suitable habitat for Bell's sage sparrow including coastal sage scrub, chaparral, and desert scrubs in Riverside lowland, Santa Ana Mountains, Desert Transition, and San Jacinto foothills Bioregions.
Include within the MSHCP Conservation Area at least 12 of 14 Core Areas and interconnecting linkages for Bell's sage sparrow. Core areas will include the Jurupa Mountains (Proposed Noncontiguous Habitat Block 2; 1,230 acres), Lake Mathews-Estelle Mountain (Existing Core C plus Proposed Extension of Existing Core 2; 23,710 acres), Wasson Canyon (Subunit 5 of Elsinore Area Plan; 2,320 acres), Sedco Hills (Proposed Linkage 8; 5,470 acres), Hogbacks (Proposed Core 2; 5,050 acres), Lake Skinner/Diamond Valley Lake (Existing Core C plus Proposed Extension of Existing Cores 5, 6, 7; 29,060 acres), Vail Lake/Wilson Valley/Aguanga (Proposed Core 7; 50,000 acres), Tule Valley, (Proposed Core 6; 4,290 acres), Lakeview Mountains (Proposed Noncontiguous Habitat Block 5; 7,150 acres), Lake Perris (Existing Core H; 17,470 acres), Badlands (Proposed Core 3; 24,920 acres), and Box Springs Mountains (Existing Noncontiguous Habitat Block A plus Proposed Constrained Linkage 8; 2,920 acres).
Include within the MSHCP Conservation Area habitat linkages between Core Areas and areas important for dispersal including the Jurupa Mountains, Reche Canyon, and San Timoteo Creek areas.
Although the distribution and habitat use of the Bell's sage sparrow is very similar to that of the coastal California gnatcatcher and Southern California rufous-crowned sparrow, the Bell's sage sparrow differs from each of these species in several factors: it occurs at higher elevations similar to the Southern California rufous-crowned sparrow but different from the coastal California gnatcatcher, it occurs in the Desert Transition bioregion, it rarely or never uses grassland habitat except possibly for dispersal, and it is more sparsely scattered at lower populations levels throughout the MSHCP Plan Area. For the purpose of the conservation analysis, potential habitat includes coastal sage scrub, chaparral, and desert scrubs within the Riverside Lowlands, San Jacinto Foothills, Santa Ana Mountains, and Desert Transition Bioregions. Bell's sage sparrow is documented to use the sparse form of chaparral which is included within the broader category of chaparral for the Plan Area (Martin and Carlson 1998). The mapping for the Plan Area does not distinguish between sparse and dense forms of chaparral. Based on these habitats, the Plan Area supports approximately 423,190 acres of potential habitat for the Bell's sage sparrow. Table 1 shows the conservation and loss of potential habitat for the Bell's sage sparrow. Overall, approximately 245,750 acres (58 percent) of potential habitat in the Plan Area will be conserved in Criteria Area or existing Public/Quasi-Public lands for all the habitats combined.
TABLE 1
SUMMARY OF HABITAT CONSERVATION
BELL'S SAGE SPARROW
| Vegetation Type | MSHCP Plan Area (Acres) |
Within MSHCP conservation Area | Outside MSHCP conservation Area | ||||
|---|---|---|---|---|---|---|---|
| Criteria Area1 (Acres) |
Public/ Quasi-Public (Acres) |
Total Within MSHCP Conservation Area (Acres) |
Rural/ Mountainous (Acres) |
Outside MSHCP Conservation Area (Acres) |
Total Outside MSHCP Conservation Area (Acres) |
||
| Habitats within Riverside Lowlands, San Jacinto Foothills, Santa Ana Mountains, and Desert Transition Bioregions | |||||||
| Desert Scrubs | 7,940 | 3,440 | 1,170 | 4,610 | 40 | 3,290 | 3,330 |
| Coastal Sage Scrub | 148,220 | 45,550 | 32,750 | 78,300 | 25,790 | 44,130 | 69,920 |
| Chaparral | 267,030 | 55,750 | 107,090 | 162,840 | 47,350 | 56,840 | 104,190 |
| TOTAL | 423,190 | 104,740 (25%) |
141,010 (33%) |
245,750 (58%) |
73,180 (17%) |
104,260 (25%) |
177,440 (42%) |
| 1 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. | |||||||
This species may occur within Forest Service lands for nesting and foraging within coastal sage scrub, and chaparral in the Santa Ana Mountains bioregion. Currently there are no database records within the Forest Service lands, however, based on the elevation and habitats available within the Cleveland National Forest, it is likely to occur within the area. The locations within the Forest Service lands are expected to be in coastal sage scrub and chaparral habitat within the Cleveland National Forest. Under the existing Forest Land Allocation plan, these potential locations or habitats generally are located within the Wildhorse and Coldwater roadless areas, San Mateo Canyon Wilderness Area and possibly the Tenaja and Verdugo Range Allotments.
As described below under Data Characterization, 98 of the 264 point localities have a high location precision. Of these 98 point localities, 34 (35 percent) will be inside the Criteria Area or Public/Quasi-Public lands. A total of 18 (18 percent) will be in the Rural/Mountainous zone. Of the 46 (47 percent) points located outside the MSHCP Conservation Area, 26 are mapped in existing residential/urban/ exotic areas.
Twelve of fourteen Core Areas will be conserved within the Jurupa Mountains (Proposed Noncontiguous Habitat Block 2; 1,230 acres), Lake Mathews-Estelle Mountain (Existing Core C plus Proposed Extension of Existing Core 2; 23,710 acres), Wasson Canyon (Subunit 5 of Elsinore Area Plan; 2,320 acres), Sedco Hills (Proposed Linkage 8; 5,470 acres), Hogbacks (Proposed Core 2; 5,050 acres), Lake Skinner/Diamond Valley Lake (Existing Core C plus Proposed Extension of Core 5, 6, 7; 29,060 acres, Vail Lake/Wilson Valley/Aguanga (Proposed Core 7; 50,000 acres), Tule Valley, (Proposed Core 6; 4,290 acres), Lakeview Mountains (Proposed Noncontiguous Habitat Block 5; 7,150 acres), Lake Perris (Existing Core H; 17,470 acres), Badlands (Proposed Core 3; 24,920 acres), and Box Springs Mountains (Existing Noncontiguous Habitat Block A plus Proposed Constrained Linkage 8; 2,920 acres). The total acreage of Core Areas within Criteria Area and Public/Quasi-Public Lands is 173,590 acres. Some additional locations of Bell's sage sparrows will be conserved within the Sycamore Canyon Regional Park, Steele Peak, North Peak Conservation Bank, Motte-Rimrock Reserve, Santa Rosa Plateau Nature Reserve, and Kabian Park. Although only one location is recorded, the MSHCP Conservation Area within the Gavilan Hills provides potential habitat for Bell's sage sparrow.
Conservation also will be provided for the habitat linkages between Core Areas and areas important for dispersal including the Jurupa Mountains, which is also conserved as a Core Area, Reche Canyon, and San Timoteo Creek areas. Other linkages that may be important for this species and that are within Criteria Area and Public/Quasi-Public Lands include the Gavilan Hills as discussed above, Temecula Creek, a Proposed Linkage to Cactus Valley, Tucalota Valley linkage between Lake Skinner/Diamond Valley Lake area and Vail Lake/Wilson Valley/Aguanga area, Tule Creek, Tenaja Corridor, and a linkage between the Santa Rosa Plateau Nature Reserve and the Santa Margarita Ecological Reserve.
Several large blocks of habitat supporting the Bell's sage sparrow will be conserved as Criteria Area and Public/Quasi-Public designations including the Core Areas for the species in the Jurupa Mountains (Proposed Noncontiguous Habitat Block 2; 1,230 acres), Lake Mathews-Estelle Mountain (Existing Core C plus Proposed Extension of Existing Core 2; 23,710 acres), Wasson Canyon (2,320 acres), Sedco Hills (Proposed Linkage 8; 5,470 acres), Hogbacks (Proposed Core 2; 5,050 acres), Lake Skinner/Diamond Valley Lake (Existing Core C plus Proposed Extended Core 5, 6, 7; 29,060 acres), Vail Lake/Wilson Valley/Aguanga (Proposed Core 7; 50,000 acres), Tule Valley, (Proposed Core 6; 4,290 acres), Lakeview Mountains (Proposed Noncontiguous Habitat Block 5; 7,150 acres), Lake Perris (Existing Core H; 17,470 acres), Badlands (Proposed Core 3; 24,920 acres), and Box Springs Mountains (Existing Noncontiguous Habitat Block A plus Proposed Constrained Linkage 8; 2,920 acres). By conserving these large blocks of habitats, the edge effects of MSHCP Conservation Areas are reduced which may reduce the effects of edge responsive species such as the brown-headed cowbird, invasion of introduced grasses, and human and urban mesopredator intrusion. Some additional locations of the Bell's sage sparrows will be conserved within the MSHCP Conservation Area outside of the Core Areas including the Sycamore Canyon Regional Park, Gavilan Hills, Steele Peak, North Peak Conservation Bank, Motte-Rimrock Reserve, Kabian Park, and Cleveland National Forest (a likely but not confirmed location).
Areas that are important for preservation for dispersal purposes between the Plan Area and other areas, but that may or may not contain large numbers of Bell's sage sparrows, include the Jurupa Mountains for connectivity to San Bernardino County which is also a Core Area for this species, Chino Hills and Cleveland National Forest for connectivity to Orange County, and the Santa Margarita Ecological Reserve and eastern Temecula Creek for connectivity to San Diego County.
Similar to the California gnatcatcher, the Bell's sage sparrow, as a year-round resident, may not be as adept at dispersing as some of the long distance migrant bird species. Unfortunately, no data is available specific to the Bell's sage sparrow, although the sage sparrow has been documented to be sensitive to fragmentation and edge effects (see below). It is assumed, based on the natural history of this species that the MSHCP Conservation Area will provide habitat linkages between the preserved Core Areas. The large block of habitat within the core population area at Lake Mathews-Estelle Mountain Reserve is connected to the Wasson Canyon population along Temescal Wash and the hillsides east of the wash with a wide linkage at a 2,000 foot minimum width. These Core Areas also are connected by the Proposed Linkage at the Gavilan Hills. Connections to the eastern foothills of the Santa Ana Mountains are located at Indian Canyon, and Horsethief Canyon. The Wasson Canyon population is connected to the Hogbacks population along the Sedco Hills Core Area, and then to the Lake Skinner population via the AD161 mitigation area and conservation of other small drainages including Warm Springs, Ken & Barkley Canyon and Tucalota Creek. The Lake Skinner population is linked to the Vail Lake/Wilson Valley/Aguanga area by preservation within the entire area in Wilson Valley as well as the eastern reach of Tucalota Creek. The Cactus Valley area is a large block of habitat connecting the Lake Skinner/Diamond Valley Lake area east to the San Bernardino National Forest, along Bautista Creek and within the large block of habitat within the Badlands. The block of habitat within the Lake Perris Core Area is connected to the Badlands along the San Jacinto River and Lamb Canyon. The Core Area in the Lakeview Mountains is somewhat isolated from other MSHCP Conservation Area areas due to existing development, however a narrow connection is provided between the north edge of the Lakeview Mountains and the San Jacinto River. The Box Springs Mountains area is connected by Reche Canyon to the Badlands.
MSHCP Conservation Area design for the Bell's sage sparrow will take into account that large scale fires damages habitat for a relatively long length of time and large areas are necessary to provide refugia for birds and to supply dispersing individuals to a recovered area. In contradiction to this, and a complicating factor, is that fire may also assist with providing additional suitable habitat for the Bell's sage sparrow. Long term fire suppression in California has allowed some of the shrub communities to reach tall, thick shrublands reducing the availability of suitable habitat. Fire management will be an important factor in addressing the conservation of this species.
Duplicate linkages also provide for the temporary loss of function of the coastal sage scrub or chaparral habitat in the event of a fire. A duplicity of habitat linkages composed of sage scrub and other undeveloped habitats which may be composed of native as well as non-native habitats may provide for dispersal. Several duplicate linkages are preserved in the MSHCP Plan Area including linkages along the Santa Ana Mountains foothills with the Interstate 15 corridor and between AD161 and the Hogbacks and between the Lake Skinner/Diamond Valley Lake area and other areas to the east.
In summary, conservation for this species will be achieved by inclusion of at least 245,750 acres of suitable Conserved Habitat and 12 of 14 Core Areas within large blocks of habitat in the MSHCP Conservation Area. In addition, 34 recent and high precision locations will be inside the Criteria Area or Public/Quasi-Public Lands, all of which are recorded for the suitable habitat of Bell's sage sparrow. Conservation also will be provided for the habitat linkages between Core Areas and areas important for dispersal including the Jurupa Mountains, which is also conserved as a Core Area, Reche Canyon, and San Timoteo Creek areas as well as other linkages as described above. The current population size of the Bell's sage sparrow is unknown. However the habitat requirements of the species and locations that constitute key populations are well documented.
The Incidental Take of the Bell's sage sparrow is difficult to quantify due to our limited knowledge of its distribution and abundance within the Plan Area. The maximum level of Incidental Take of Bell's sage sparrow can be anticipated by the loss of the number of acres of habitat that will become unsuitable for this species. About 177,440 acres of potential habitat for the Bell's sage sparrow will be outside the Criteria Area and Public/Quasi-Public designations, or about 42 percent of the total potential habitat and individuals within these areas are subject to Incidental Take consistent with the Plan. Of this, approximately 73,180 acres (17 percent) of potential habitat are located within Rural/Mountainous designation areas, which may provide some habitat value, but will not be managed for the benefit of covered species and cannot be relied upon as conserved habitat for the Bell's sage sparrow. These areas include the Santa Rosa Plateau, Santa Rosa Hills, and a portion of the Badlands.
Core areas not conserved within Criteria Area and Public/Quasi-Public designations include the Santa Rosa Plateau and Santa Rosa Hills. A total of 64 recent and high precision point locations of the Bell's sage sparrow will be outside the Criteria Area and Public/Quasi-Public designations. Of these 64 point locations, 18 (18 percent) will be in the Rural/Mountainous zone. Of the 46 (47 percent) points located outside the MSHCP Conservation Area, 26 are mapped in existing residential/urban/exotic areas.
The UCR location database contains approximately 352 location records for the Bell's sage sparrow dated from 1887 to 1999. Due to its overlap in habitat with the gnatcatcher, the Bell's sage sparrow has probably been well surveyed within sage scrub habitat. In areas where there is no requirement for surveys for the gnatcatcher, the sage sparrow is likely under represented and the documentation of presence in outlying areas probably has not been accomplished. Approximately 264 of the records are relatively recent (within the past 10 years) and approximately 98 of these records are precise. Approximately 26 of these recent and precise records are located within residential or developed habitats and may no longer be extant, the rest are located within sage scrub, chaparral or other undeveloped habitats and may represent existing locations.
The sage sparrow has a moderate amount of literature available for it. It has been well studied with the suite of species located within the shrub-steppe region and has general natural history information well summarized within the ornithological literature. Although, the subspecies and information for the Plan Area have a relatively little amount of literature available, the species as a whole has been well documented for its distribution and biology.
The sage sparrow prefers semi-open habitats with evenly spaced shrubs 1 to 2 meters high (Martin and Carlson 1998). Vertical structure, habitat patchiness, and vegetation density may be more important in habitat selection by the sage sparrow than the specific shrub species, but this sparrow is closely associated with sagebrush throughout most of its range (Wiens and Rotenberry 1981). The species is often missing from what appears to be suitable habitat, so other unknown habitat characteristics may be important (Martin and Carlson 1998).
Bell's sage sparrow is an uncommon to fairly common but localized resident breeder in dry chaparral and coastal sage scrub along the coastal lowlands, inland valleys, and in the lower foothills of local mountains. In transmontane California, it occupies sagebrush, alkali desert scrub, desert scrub, and similar habitats. In cismontane California, it frequents chaparral dominated by chamise, and coastal scrub dominated by sage. Other coastal scrub plant species associated with Bell's sage sparrow include Artemisia, Purshia, and Atriplex as well as mixed brush and cactus patches in arid washes (Grinnell and Miller, 1944). The preference for chamise chaparral appears to occur only in the more northern parts of its range. High overgrown chaparral stands generally have fewer sage sparrows than shorter shrubs recovering from recent fires (Martin and Carlson 1998). Bell's sage sparrow is also found in big sagebrush at higher elevations in southern mountains (Martin and Carlson 1998).
Bell's sage sparrow seeks cover in fairly dense stands in chaparral and scrub habitats in the breeding season, and they forage on the ground beneath and between shrubs. The species uses similar habitat structure in the winter, however the habitat may be in more arid, open shrub habitats (Zeiner, et al. 1990).
The sage sparrow occurs in western North America from the interior west-central Washington, within the eastern portion of Idaho to western Wyoming, through Nevada, Utah, Colorado south to New Mexico, Arizona and into California. The subspecies Bell's sage sparrow, A. belli belli, occurs as a nonmigratory resident on the coastal ranges of California, on the western slope of the central Sierra Nevada mountains, and into northwestern Baja California (Bent, 1968). Generally it is found throughout the year in southern California and Baja areas where the winter range overlaps with the breeding range (Martin and Carlson, 1998).
Zeiner, et al. (1990) characterized the distribution, abundance and seasonality of the Bell's sage sparrow as follows. It is a common to uncommon resident and summer visitor. In summer, it is uncommon to common east of the Cascade Range and Sierra Nevada, in foothills bounding the Central Valley, and in the Transverse, Peninsular, and coastal ranges from Trinity Co. south to the Mexican border. It is not migratory in many areas, but mostly withdraws from higher elevations and the northern Great Basin in winter and moves to southern deserts. It is most common from the western edge of Owens Valley, Inyo County, south through southern Sierra Nevada and the western edge of Mojave Desert to desert slopes of the Transverse Ranges. On coastal slopes, it is mostly absent north of Sonoma County, and uncommon and local to the south. It occurs only locally at montane elevations, mostly in southern California. The resident race, A. b. clementeae, on San Clemente Island, is classified as a Federally listed threatened species (Grinnell and Miller 1944, McCaskie, et al. 1979, Garrett and Dunn 1981).
The Bell's sage sparrow has a wide but sparse and patchy distribution in western Riverside County. Bell's sage sparrow may occur in extant stands of dry chaparral and coastal sage scrub habitat nearly throughout the Plan Area within the Riverside lowlands, San Jacinto Foothills, Santa Ana Mountains and Desert Transition Bioregions. Although difficult to assign Core Areas to the broad but sparse scatter of database locations some trends of clusters of locations appear to include the areas in the vicinity of Jurupa Mountains, Lake Mathews-Estelle Mountain, Wasson Canyon, Santa Rosa Plateau, Sedco Hills, Hogbacks, Lake Skinner/Diamond Valley Lake, Vail Lake/Wilson Valley/Aguanga, Tule Valley, Santa Rosa Hills, Lakeview Mountains, Lake Perris, Badlands, and Box Springs Mountains (B. Carlson 1998 pers. comm.). Although these areas are considered Core Areas, none of the areas consists of very high or very dense populations except for the Wasson Canyon and Lake Skinner/Diamond Valley Lake areas.
Genetics: The sage sparrow varies in morphometrics, plumage coloration, and habitat selection in correlation with features that roughly agree with observed genetic and biochemical variation. Within the three subspecies, belli, canescens, and nevadensis, the average percentage of nucleotide difference is 0.1 percent within populations and 0.4 percent between populations within the same subspecies, and 0.6 percent between subspecies (Johnson and Cicero 1991).
Diet and Foraging: Bell's sage sparrows predominantly forage on the ground, mostly by gleaning from the ground and low foliage of shrubs; it rarely catches insects on the wing (Zeiner, et al. 1990). The sage sparrow is categorized as a ground foraging omnivore during the breeding season and a ground gleaning granivore during the nonbreeding period (Martin and Carlson 1998). It feeds mostly on insects, spiders, and seeds while breeding, switching to grasshoppers in the late breeding season (Rotenberry 1980), and mostly on seeds in winter; it also takes green foliage. Apparently, the species drinks regularly (Bent 1968, Smyth and Coulombe 1971). Captives could not survive exclusively on seeds unless supplemented with succulent foods. When water was available, captives drank an average of 49 percent (range 12-99 percent) of body weight daily. It may meet a portion of its water needs from invertebrate foods (Moldenhauer and Wiens 1970).
Daily Activity: A study in Oregon revealed the following breakdown of a sage sparrow's day: 51 percent singing, 35 percent foraging, 12 percent inactivity, 4 percent locomotion and 3 percent aggression (Martin and Carlson 1998). The Bell's sage sparrow exhibits year-long, diurnal activity (Zeiner et al. 1990).
Reproduction: Bell's sage sparrow usually nests in sagebrush or chaparral, and may have two broods per nesting season (Ehrlich, et al. 1988). They prefer to nest in an intermediate sized shrub, 50 to 70 centimeters tall, which may represent a compromise between shrubs that provide favorable foraging sites, avenues of movement, and sufficient cover Martin and Carlson 1998). The subspecies uses a very diverse selection of shrubs including brittlebush (Encelia farinosa), black sage (Salvia mellifera), California buckwheat (Eriogonum fasciculatum), California sagebrush (Artemisia californica), bush mallow (Malocothamnus fasciculatum), chamise (Adenostema fasciculata), white sage (Salvia apiana), valley cholla (Opuntia parryi), ceanothus (Ceanothus sp.), willow (Salix sp.) and bunchgrass species (Martin and Carlson 1998). Individuals remain monogamously pair bonded throughout the year, although partners may change after the breeding season (Martin and Carlson 1998). The nest is a cup of dry twigs and herb stems; it is lined with shreds of bark and grass and contains an inner lining of finer bark fiber, grass, fur, hairs, wool tufts, feathers (Harrison 1978). The nest is located on the ground beneath a shrub; or in a shrub usually 0.15 to 0.45 meters (6-18 inches) above ground, but up to 1 meter (39 inches) in height. It breeds from late March to mid-August with a peak in May and June. The clutch size is 3-5 eggs, usually 3 or 4 eggs. Incubation is typically 13-16 days, and the altricial young fledge in 9-11 days (Harrison 1978, Ehrlich, et al. 1988, Reynolds 1981).
Survival: Sage sparrow populations exhibit substantial yearly fluctuations in population size from unknown causes (30-90 individuals/0.4m2) (Rotenberry 1980, Wiens, et al. 1986, Rotenberry and Wiens 1991). Variations in clutch size have been most strongly correlated with predation; in some cases, predation was by snakes, in other instances by Townsend's ground squirrels (Rotenberry and Wiens 1989).
Dispersal: Young Bell's sage sparrow have been recorded 800 to 900 meters from the nest site by the following spring. Ten hatch-year individuals banded during the breeding season moved 75 to 600 meters by the following spring (Martin and Carlson 1998).
Socio-Spatial Behavior: Male sage sparrows show a strong site tenacity to the breeding territory, even if the habitat is greatly modified (Ehrlich, et al. 1988). In Oregon, Gashwiler (1977) recorded 24-33 pairs per 40 hectares (100 acres). In Nevada, Gustafson (1975) recorded 30 males per 40 hectares (100 acres). Weston and Johnston (1980) reported a density varying from 27-85 individuals per 40 hectares (100 acres) in sagebrush habitat in Mono County. Territory size of the species is highly variable (0.9 to 8.1 acres) depending on local environmental conditions (Reynolds 1981; Rich 1980; Wiens, et al. 1986). For A. belli, the territories in San Diego and Riverside counties varied from 0.75 to 5.7 hectares (Lovio 1993).
Community Relationships: In Nevada, Bond (1940) observed predation by great horned owls. The Bell's sage sparrow is a rare host to cowbird parasitism (Terres 1980).
Long-term fire suppression alters the pattern of natural plant succession and allows communities to reach tall, thick shrublands, probably reducing the availability of sage sparrow habitat for breeding (Martin and Carlson 1998).
Increasing fire frequency in some areas results in the invasion of exotic weeds. With increased fire frequency, native plants are killed and seed reservoirs of grasses and shrubs are depleted and replaced with exotic annuals (Martin and Carlson 1998).
Loss of coastal sage scrub habitat, which includes foraging, roosting and nesting areas, to development activities, fire, and agriculture appear to the primary threats to the Bell's sage sparrow in western Riverside County. Local populations in some areas of southern California have been extirpated as a result of urbanization and agricultural conversion (Barbara Carlson 1998 pers. comm.).
Threats from brood parasitism and predation have not been quantified (Martin and Carlson 1998).
Generally associated with dense stands of chaparral or coastal sage scrub, Bell's sage sparrow is one of the first bird species to return after fires in these preferred habitat areas (B. Carlson 1998 pers. comm.). Sage sparrow populations exhibit substantial yearly fluctuations in population sizes, the cause of which is unknown (30-90 individuals/0.4m2) (Rotenberry 1980, Wiens, et al. 1986, Rotenberry and Wiens 1991). The species also shows differences in their behavior from year to year and from habitat area to habitat area (Wiens et al. 1990).
The territory size of sage sparrows appears to be positively related to coverage of spinescent shrub species and to an index of vegetational horizontal heterogeneity or patchiness, while varying inversely with total vegetation coverage and its horizontal variation and with coverage of grass and sagebrush. Thus, over this range of sites, the sage sparrow territories generally were smaller in areas with more grass and sagebrush and larger in the more heterogeneous areas dominated by spinescent shrubs (Wiens et al. 1985). Territories rapidly expand in size at low densities, with no apparent upper limit. At intermediate to high densities, however, territory size hardly changes with increasing density, suggesting that a minimal acceptable size of territory has been reached and that all usable areas, including suboptimal habitat areas have been occupied (Wiens et al. 1985).
Protective fencing in the Mojave Desert increased abundance and nesting activity of sage sparrows (Brooks 1999). Bolger, et al. (1997) studied the 20-most common bird species within a 260 km2 area of coastal San Diego County in relation to edge/fragmentation sensitivity. Bell's sage sparrow was found to be one of four species whose abundance is most reduced by presence of edges/ fragmentation.
Because of the dense habitat and general tendency of this subspecies to stay below the plant canopy and run behind and beneath bushes, it is more difficult to detect than other subspecies (Bent 1968). Population size estimates may be inaccurate owing to the secretive habits of the species. It moves under cover rapidly when approached and incubating birds rarely leave the nest. However, spring counts to assess population numbers are enhanced by the frequent seasonal vocalizations.
The sage sparrow shows an approximate one year time lag in response to habitat changes. This may be due to the site tenacity of the breeding individuals. Such time lags complicate the attempts to formulate management policies on the basis of short-term before and after surveys. It may be necessary to conduct longer periods of post-treatment studies in order to assess true changes in population sizes (Wiens and Rotenberry 1985). Additionally, territory size did not increase significantly over the short term in areas where vegetation was removed and in fact, territory fidelity or tenacity may be a factor for the first 12 years after vegetation removal (Wiens, et al. 1985). In addition, if insular patches of vegetation are left within territories, sage sparrows may adjust to removal without significant density changes. Where individuals are less abundant, they appear to increase territory size with no apparent upper limit, but do not completely saturate the available habitat (Wiens and Rotenberry 1985).
Fragmentation of shrubland habitats has the potential to affect significantly, the conservation of shrub-obligate species because of the potential permanence of the disturbance (Knick and Rotenberry 1995). Disturbance of shrub habitats in the shrubsteppe regions has the potential to allow invasion of exotic species, including grasses, and increase the fire frequency which then changes the dominance of the shrub areas (Knick and Rotenberry 1995). For the Bell's sage sparrow, the total shrub cover and abundance of shrub species (predominantly sagebrush) are important habitat characteristics. Additionally, the importance of landscape characteristics for the Bell's sage sparrow, especially those relating to fragmentation, have been implicated. The Bell's sage sparrow is more likely to remain in an area that has high shrub cover, low disturbance, combined with large patch size and high within-site spatial similarity. The scale at which species presence is influenced has not been quantified but has been determined to be much larger than the size of an individual's home range (Knick and Rotenberry 1995).
Bent, A.C. 1968. Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies. 3 Parts. Edited by O.L. Austin Fr. U.S. Natl.Mus.bull. 237. 1,889 pp.
Bolger, D. T., T. A. Scott and J. T. Rotenberry. 1997. Breeding bird abundance in an urbanizing landscape in coastal Southern California. Conservation Biology 11:406-421.
Bond, R. M. 1940. Food habits of horned owls in the Pahranagat Valley, Nevada. Condor 42:164-165.
Brooks, Matthew. 1999. Effects of protective fencing on birds, lizards, and black-tailed hares in the Western Mojave Desert. Environmental Management 23: 387-400.
Carlson, B. 1998. Pers. Comm.
Ehrlich, R. R., D. S. Dobkin, and D. Wheye. 1988. The Birder's Handbook: A field guide to the natural History of North American Birds. Simon and Schuster, New York.
Garrett, K., and J. Dunn. 1981. Birds of southern California. Los Angeles Audubon Soc. 408pp.
Grinnell, J. and A.H. Miller. 1944. The distribution of the birds of California. Pacific Coast Avifauna 27.
Gashwiler, J. S. 1977. Bird populations in four vegetational types in central Oregon. U.S. Dep. Inter. Fish and Wildl. Serv., Portland OR. Special Tech. Rep. No. 205. 20pp.
Gustafson, J. R. 1975. A sage sparrow egg in a black-throated sparrow nest. Auk 92:805- 806.
Knick, S. T. And J. T. Rotenberry.1995. Landscape characteristics of fragmented shrubsteppe habitats and breeding passerine birds. Conservation Biology 9:1059- 1071.
Harrison, C. 1978. A field guide to the nests, eggs and nestlings of North American birds. W. Collins Sons and Co., Cleveland, OH. 416pp.
Johnson, N. K., and C. Cicero. 1991. Mitochondrian DNA sequence variability in two species of sparrows of the genus Amphispiza. Proc. Inter. Congr. Ornithol. 20: 600-610.
Lovio, J. C. 1993. Diegan coastal sage scrub. I. Breeding bird census. J. Field Ornithol. 64: 95-96.
Martin, John W. and Barbara A. Carlson. 1998. Sage sparrow (Amphispiza belli) In The Birds of North America, No. 326 (A. Poole and F. Gill, eds.) The Birds of North America, Inc., Philadelphia, PA.
McCaskie, G., P. De Benedictis, R. Erickson, and J. Morlan. 1979. Birds of northern California, an annotated field list. 2nd ed. Golden Gate Audubon Soc., Berkeley. 84pp.
Moldenhauer, R. R., and J. A. Wiens. 1970. The water economy of the sage sparrow, Amphispiza belli nevadensis. Condor 72:265-275.
Reynolds, T.D. 1981. Nesting of the sage thrasher, sage sparrow, and Brewer's sparrow in southeastern Idaho. Condor 83: 61-64.
Rich, T. 1980. Territorial behavior of the sage sparrow: spatial and random aspects. Wilson Bulletin 92: 425-438.
Rotenberry, J. T. 1980. Dietary relationships among shrub-steppe passerine birds: competition or opportunism in a variable environment? Ecol. Monogr. 50: 93-110.
Rotenberry, J. T. and J. A. Wiens. 1989. Reproductive biology of shrubsteppe passerine birds: Geographical and temporal variation in clutch size, brood size and fledging success. Condor 91:1-14.
Rotenberry, J.T., and J.A. Wiens. 1991. Weather and reproductive variation in shrub-steppe sparrows: a hierarchical analysis. Ecology 72: 1325-1335.
Smyth, M., and H. M. Coulombe. 1971. Notes on the use of desert springs by birds in California. Condor 73:240-243.
Terres, J. K. 1980. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knopf, New York, New York. 1109pp.
Weston, H. G., Jr., and D. Johnston. 1980. Summer and fall censusing of bird populations in the Bodie/Coleville region. Harvey and Stanley Assoc., Alviso, CA. Rep. To U. S. Dep. Inter. Bur. Land Manage., Bakersfield CA Contract No. CA-01.
Wiens, J.A. and J.T. Rotenberry. 1981. Habitat associations and community structure of birds in shrubsteppe environments. Ecological Monographs 51: 21-41.
Wiens, J.A. and J.T. Rotenberry. 1985. Response of breeding passerine birds to rangeland alteration in a North American shrubsteppe locality. J. Applied Ecology 22: 655-668.
Wiens, J.A. and J.T. Rotenberry, and B. Van Horne. 1985. Territory size variation in shrubsteppe birds. Auk 102: 500-505.
Wiens, J.A., J.T. Rotenberry, and B. Van Horne. 1986. A lesson in the limitations of field experiments: shrub-steppe birds and habitat alteration. Ecology 67: 365-376.
Wiens, J. A., B. Van Horne, and J. T. Rotenberry. 1990. Comparisons of the behavior of sage and Brewer's sparrows in shrubsteppe habitats. Condor 92: 264-266.
Zeiner, D. C., W., F. Laudenslayer, Jr., K. E. Mayer, M. White. Editors. 1990. California's Wildlife. Volume 2. Birds. State of California, Department of Fish and Game. Sacramento, California. 731 pp.
black-crowned night heron (Nycticorax nycticorax) (Breeding Rookeries)
State: None
Federal: None
The black-crowned night heron is relatively well-distributed throughout the MSHCP Plan Area within its suitable habitat; however, it is not predictably distributed within all suitable areas. It occurs at almost all of the open water bodies where emergent or riparian vegetation is present and many of the playas and riparian drainages that may provide foraging opportunities. There are several Core Areas for this species, including Mystic Lake/San Jacinto Wildlife Area, Prado Basin/Santa Ana River, and Collier Marsh. The breeding locations, which have been documented as active or historic, are located at specific sites that require conservation. Because it is well known for using emergent habitat, riparian areas for breeding, and ponds and other aquatic habitat for foraging, but has specific locations that are used for breeding, it is assumed that this species will respond to a landscape level of management with site-specific requirements (e.g., breeding rookeries).
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 16,560 acres of suitable nesting and foraging habitat for the black-crowned night heron including freshwater marsh, playas and vernal pools, riparian scrub, woodland, and forest, and cismontane alkali marsh.
Include within the MSHCP Conservation Area at least the 3 known and historic breeding locations in the Prado Basin/Santa Ana River (9,670 acres), Mystic Lake/San Jacinto Wildlife Area (Subunit 4 of Reche Canyon/Badlands Area Plan; 2,690 acres), and Collier Marsh areas (Proposed Linkage 2; 160 acres).
A 100-meter buffer will be established around the Core Areas identified in Objective 2 as they are incorporated into the MSHCP Conservation Area.
The black-crowned night-heron is virtually restricted to more aquatic wetlands for foraging but may use more forested riparian areas for nesting (Garrett and Dunn 1988). Because they will use a relatively wide variety of wetlands for various parts of their life history, a wide range of habitats has been included for this analysis. For the purpose of the conservation analysis, potential habitat for the black-crowned night-heron has been separated into the primary breeding habitat which includes freshwater marsh and riparian scrub, forest, and woodland. The secondary habitat, which is composed only of foraging habitat includes playas and vernal pools and cismontane alkali marsh. Based on these habitats, the Plan Area supports approximately 20,560 acres of potential habitat for the black-crowned night-heron composed of 12,680 acres of primary breeding and foraging habitat and 7,880 acres of secondary foraging habitat. Table 1 shows the conservation of potential habitat for the black-crowned night-heron. Overall, approximately 9,840 acres (78 percent) of potential primary breeding and foraging habitat in the Plan Area will be conserved in Criteria Area or existing Public/Quasi-Public Lands. Approximately 6,720 acres (86 percent) of secondary foraging habitat will be conserved in Criteria Area or existing Public/Quasi-Public lands.
TABLE 1
SUMMARY OF HABITAT CONSERVATION
BLACK-CROWNED NIGHT-HERON
| Vegetation Type | MSHCP Plan Area (Acres) |
Within MSHCP conservation Area | Outside MSHCP conservation Area | ||||
|---|---|---|---|---|---|---|---|
| Criteria Area1 (Acres) |
Public/ Quasi-Public (Acres) |
Total Within MSHCP Conservation Area (Acres) |
Rural/ Mountainous (Acres) |
Outside MSHCP Conservation Area (Acres) |
Total Outside MSHCP Conservation Area (Acres) |
||
| Riverside Lowlands and San Jacinto Foothills Bioregions | |||||||
| Primary Habitat for Breeding and Foraging | |||||||
| Freshwater Marsh | 470 | 170 | 240 | 410 | 0 | 60 | 60 |
| Riparian Scrub, Woodland, Forest | 12,210 | 3,570 | 5,860 | 9,430 | 180 | 2,600 | 2,780 |
| Subtotal Primary Habitat | 12,680 | 3740 (30%) |
6100 (48%) |
9840 (78%) |
180 (1%) |
2660 (21%) |
2840 (22%) |
| Secondary Habitat for Foraging | |||||||
| Playas and Vernal Pools | 7,870 | 3,830 | 2,880 | 6,710 | 0 | 1,160 | 1,160 |
| Cismontane Alkali Marsh | 10 | 10 | 0 | 10 | 0 | 0 | 0 |
| Subtotal Secondary Habitat | 7,880 | 3,840 (49%) |
2,880 (37%) |
6,720 (86%) |
0 (0%) |
1,160 (14%) |
1,160 (14%) |
| TOTAL | 20,560 | 7,580 (37%) |
8,980 (44%) |
16,560 (81%) |
180 (1%) |
3,820 (18%) |
4,000 (19%) |
| 1 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. | |||||||
In addition, the Riparian/Riverine Areas and Vernal Pools policy described in Section 6.1.2 of the MSHCP, Volume I, provides for conservation of wetlands, which provide habitat for this species, through avoidance and minimization. Mitigation for impacts to wetlands shall be incorporated in accordance with the "No Net Loss" policy of federal and state wetland regulations. The proposed mitigation shall be directly related to the functions and values of the wetland as related to this species and result in equivalent replacement.
As described below under Data Characterization, 29 of the 69 recent point localities have a high location precision. Of these 29 point localities, 5 will be inside the Criteria Area and 5 will be inside the Public/Quasi-Public Lands. In addition, the one known nesting colony location and the potential or historical nesting locations are within the Criteria Area or Public/Quasi-Public Lands. A total of 17 point localities will be outside of the MSHCP Conservation Area. However, these locations, if within a wetland area, will continue to receive protection by the wetland policy. Conservation of this species can be considered from a landscape perspective because the species has well identified habitat requirements.
In addition, there are definable locations composed of Core Areas for focusing conservation efforts which are included within the MSHCP Conservation Area. These conserved Core Areas include the 3 known and historic breeding locations in the Prado Basin/Santa Ana River (9,670 acres), Mystic Lake/San Jacinto Wildlife Area (Subunit 4 of Reche Canyon/Badlands Area Plan; 2,690 acres), and Collier Marsh areas (Proposed Linkage 2; 160 acres). The Core Area at Prado Basin/Santa Ana River includes the only known nesting colony for the black-crowned night-heron and the Core Area at Mystic Lake/San Jacinto Wildlife Area is an historic or potential breeding location. A total of 12,520 acres of Core Areas are conserved within the MSHCP Conservation Area. Additionally, as part of the reserve assembly, a 100-meter buffer will be established around the Core Areas identified above as they are incorporated into the MSHCP Conservation Area.
Several large blocks of habitat including potential or historic foraging and nesting areas for the black-crowned night-heron will be conserved as Criteria Area and Public/Quasi-Public Lands including the Prado Basin/Santa Ana River, Lake Skinner, Diamond Valley Lake, Lake Mathews, Mystic Lake, San Jacinto Wildlife Area/Mystic Lake, Lake Perris, Wasson Canyon, Temecula and Murrieta creeks, San Timoteo Creek, Temescal Wash, Lake Elsinore, and Vail Lake. The MSHCP Conservation Area will provide adequate habitat for foraging during nomadic visits to the area and migratory stopovers as well as habitat containing potential nest sites with adequate protection around each nest site and foraging areas during the breeding season. Foraging areas are provided at Vail Lake, Lake Skinner, Diamond Valley Lake, San Jacinto Wildlife Area/Mystic Lake, Lake Perris, Lake Elsinore, Lake Mathews, Prado Basin and Santa Ana River, and a variety of other smaller riparian and wetland areas. Potential and known nest sites are provided in the San Jacinto Wildlife Area/Mystic Lake, Collier Marsh, and Prado Basin and foraging for a potential breeding season is provided in the riparian and marsh areas within and around Collier Marsh, within the Santa Ana River system and along the San Jacinto River near the San Jacinto Wildlife Area and Mystic Lake. These MSHCP Conservation Area locations are interconnected as well, though the ability of this species to move long distances may reduce the importance of these linkages for this species.
In summary, conservation for this species will be achieved by inclusion of at least 16,560 acres of suitable Conserved Habitat including 9840 acres of primary breeding and foraging habitat and 6,720 acres of secondary foraging habitat. Additionally, the three core known or potential breeding locations, Prado Basin/Santa Ana River, Collier Marsh, and Mystic Lake/San Jacinto Wildlife Area within large blocks of habitat are included in the MSHCP Conservation Area. As these Core Areas are incorporated into the MSHCP Conservation Area, a 100-meter buffer will be established around each Core Areas. The current population size of the black-crowned night-heron is unknown.
The Incidental Take of the black-crowned night-heron is difficult to quantify at this time owing to our limited knowledge of the precise location and extent of nesting sites and the fact that losses may be masked by fluctuations in abundance and distribution during the life of the permit. However, the level of Take of black-crowned night-heron can be anticipated by the loss of the number of acres of habitat that will be impacted or become unsuitable for this species. About 2,840 acres (22 percent) of potential primary breeding and foraging habitat for the black-crowned night-heron will be outside the Criteria Area and Public/Quasi-Public Lands. Approximately 1,160 acres (14 percent) of potential secondary foraging habitat for the black-crowned night-heron will be outside the Criteria Area and Public/Quasi-Public Lands.
This comprises approximately 19 percent of the total potential habitat. No Take of nesting colonies will occur. The estimate of Incidental Take is consistent with the anticipated land uses and the application of the riparian/riverine area and vernal pool avoidance and land use adjacency policies/guidelines.
Data reviewed includes the University of California, Riverside, GIS data base, the California Natural Diversity Data Base (CNDDB), and available literature.
The UCR location database includes approximately 79 records for the black-crowned night-heron within the Plan Area dated from 1900 to 2000. A total of approximately 69 records are relatively recent (dated since 1990) and of these recent records, 29 are high precision records that can be accurately placed within the area. The habitat types associated with these recent and high precision data records include riparian, agriculture, alluvial, grassland, alkali playa, open water, sage scrub, and residential. The residential habitat records may reflect records that are either no longer extant or where the location is a small pocket of suitable habitat within or adjacent to a developed area. The upland records or records in habitat that is not suitable may also be records of the species observed in a small pocket of suitable habitat that is adjacent to the upland habitat. Breeding locations have not been recorded specifically within the database but have been documented from other sources as identified below.
Black-crowned night-herons require marshes, ponds, reservoirs, and estuaries for foraging and also occur along the margins of lacustrine, large riverine, and fresh and saline emergent habitats and, rarely, in kelp beds in marine subtidal habitats (Garrett and Dunn 1981; Gallagher 1997). Its habitat requirements are varied, including all types of wetland areas including swamps, streams, rivers, margins of pools, ponds, lakes, lagoons, tidal mudflats, fresh, brackish, and salt water ecosytems and even using man-made ditches, canals, reservoirs, and wet agricultural fields (Davis 1993). In inland areas, most colones are associated with large wetlands. These wetland areas, if they rely on rainfall, may have varying water levels. Therefore, black-crowned night-herons may fluctuate in their usage of such inland areas (Davis 1993). It nests and roosts in dense-foliaged trees, not always near water, and in dense, fresh or brackish emergent wetlands (Grinnell and Miller 1944). As might be expected of a widely distributed, opportunistic forager, these birds use a broad spectrum of habitat types for nesting, and choose nest sites from ground to 160 feet in height (Palmer 1962). Most colony sites are on islands, in swamps, or over water, suggesting that site selection may be related to predator avoidance. The variety of substrates used for nesting is enormous including oak trees, willow trees, poison ivy, box elder trees, cattails, and areas level with the water surface supported by floating dead vegetation (Davis 1993). It often rests on piers and pilings (Zeiner, et al. 1990).
Black-crowned night-herons breed in the western hemisphere from British Columbia eastward to Nova Scotia southward locally through the Americas to southern South America. The species winters locally from Washington to New England southward throughout the remainder of the breeding range (AOU 1998). The distribution of the species is generally determined by the suitable wetland habitat for feeding. The colonies are locally distributed within this range and they often occur on islands (Davis 1993).
Hunting, disturbance at breeding colonies, drainage of wetlands, and land development for homes and recreation have caused declines in heron numbers (Gross 1923; Davis 1993). DDT and other pesticides are thought to have caused local reproductive failure and population declines but convincing documentation is lacking and sparse census data from the early 20th century makes trend analysis difficult (Davis 1993).
Zeiner, et al. (1990) summarize the distribution, abundance, and seasonality of the black-crowned night-heron within California as follows. The black-crowned night-heron is a fairly common, year-long resident in lowlands and foothills throughout most of California, including the Salton Sea and Colorado River areas, and very common locally in large nesting colonies. It is a common nesting species on the northeastern plateau of California from April to August. It is uncommon in the northwestern part of the state, and rare in northeastern California in midwinter. It is an uncommon transient and rare species in winter in the southern deserts, and rare on the Channel Islands. It is seldom seen in the mountains, but formerly nested at Big Bear Lake in San Bernardino Mts. (Cogswell 1977, McCaskie, et al. 1979, Garrett and Dunn 1981). In southern California, the species generally occurs locally throughout as a year round resident except for mountainous and desert areas (Garrett and Dunn 1981). Rookeries are scarce within southern California. It is a local migrator, dispersing widely from breeding colonies after nesting (Gill and Mewaldt 1979). Much of the breeding population from northwestern and northeastern California probably moves southward and is absent from those areas in midwinter.
The black-crowned night-heron may be found throughout the Plan Area in appropriate habitat within Riverside lowland and San Jacinto Foothills Bioregions. The only known recently active rookery in western Riverside County is in the Prado Basin (Patten 1998, pers. comm.) . However, there was no direct evidence of nesting in the Prado Basin in recent years (Pike, 2001, pers. comm.). Additional potential locations include Collier Marsh, Mystic Lake/San Jacinto Wildlife Area (the species formerly bred at this locale [Garrett and Dunn 1981]), Lake Mathews, Vail Lake, Lake Perris, and Lake Skinner.
Other geographic locations recorded within the U.C. Riverside database include: Santa Ana River, Temescal Wash, Cajalco Creek, Woodcrest, Moreno Valley, Lake Perris, San Timoteo Creek, San Jacinto River, Winchester, Canyon Lake, Temecula Creek, and Lake Skinner.
Genetics: Shel