Loggerhead Shrike (Lanius ludovicianus) Potential Occurrence: Nesting Not Expected to Occur



Дата22.04.2016
Памер12.87 Kb.
#19847
Aves (Birds): Passeriformes, Laniidae

Loggerhead Shrike (Lanius ludovicianus)

Potential Occurrence: Nesting Not Expected to Occur



Status: (Nesting)

Federal: none

State: SSC

Other: USFWS: BBC



S
Photo: Larry Thompson
pecies Description:
The Loggerhead Shrike has a proportionally large head that is grey with black bill and facemask. It has grey upperparts and white underparts with black accents on the wings and tail. The bill is hooked at the tip. “Slightly smaller than an American Robin,” they are 9 inches in length, with a wingspan of 12 inches (Granholm 1990; Sibley 2000).

Distribution: This species has a widespread breeding distribution in central Canada and the American Midwest, and a year-round distribution across the southern half of the United States and extending through Mexico (Soule 1995). A year-round resident in most of California, the Loggerhead Shrike does not breed in the high Sierras and is known to spend only the winters on the North Coast north of Mendocino County (Zeiner 1990).

Life History & Threats: As predatory songbirds, they do not have large talons, so these shrikes instead use thorns and barbed wire to impale their prey, which are mainly insects and also vertebrates (including small mammals, other birds, and reptiles) (Sibley 2000; Yosef 1996). Nests are built in shrubs or small trees adjacent to grasslands and 4-6 eggs per clutch are laid between February and July. Nestlings are independent about 36 days after hatching (Soule 1995). The Loggerhead Shrike has become endangered in the northeastern part of its North American range and overall has declined 71% in the past 40 years, putting it on the Audubon watchlist (National Audubon Society 2010).

Habitat & Habitat Associations: Brushy habitat along field edges, open country with short vegetation, riparian areas, and agricultural fields (Yosef 1996).

A common resident and winter visitor in lowlands and foothills throughout California. Prefers open habitats with scattered shrubs, trees, posts, fences, utility lines, or other perches. Highest density occurs in open-canopied valley foothill hardwood, valley foothill hardwood-conifer, valley foothill riparian, pinyon-juniper, juniper, desert riparian, and Joshua tree habitats. (From Granholm 1990)

Short grass with isolated trees or shrubs, especially pastureland (From National Audubon Society 2010)

Nesting Habitat: Nests are built in shrubs or small trees adjacent to grasslands (National Audubon Society 2010).

Conceptual Basis for GIS Model Development: We mapped potential Loggerhead Shrike habitat as:


  • grasslands

  • agricultural fields

  • chaparral

  • riparian. Note that riparian vegetation was mapped as a 130-m buffer along the main stem of Rancheria Creek. Riparian woodland, forest and scrub is disjunct within this area.

  • cismontane woodland (i.e., mixed, montane mixed, and single dominant hardwoods with < 40% canopy cover)

Possible best habitat was mapped in the above areas as grasslands and agricultural fields.

Potential Occurrence in the Galbreath Wildlands Preserve: Protection status for this species applies to nesting individuals.

Habitat: The quality of nesting habitat for Loggerhead Shrikes is good in the Preserve (Figure 88). Riparian forests on the Preserve are poorly developed and patchy in distribution and likely do not provide the open woodland habitat preferred for nesting. However, open forests are of much higher quality and are relatively abundant throughout the Preserve. Grasslands and agricultural areas also provide quality nesting habitat for this species.

Nearest Occurrence:

Documented Occurrences in the Galbreath Wildlands Preserve: This species has not been observed on the Preserve. To our knowledge no surveys have been conducted.

Nearest Occurrence to the Galbreath Wildlands Preserve: This species has not been reported to occur in USGS quads adjacent to the Preserve. The westernmost range of the breeding range of Loggerhead Shrikes terminates in eastern Mendocino County, approximately 20 miles northeast of the Preserve (Shuford and Gardali 2008).

Summary: Nesting Loggerhead Shrikes are “Not Expected to Occur” in the Preserve because breeding is limited to areas further inland.

References

Granholm S. 1990.Loggerhead Shrike. California Wildlife Habitat Relationships System Life History & Range Maps. . Accessed 2010 Jul 20

National Audubon Society. 2010. Birds in Decline: Loggerhead Shrike. . Accessed 2010 Jul 20.

Sibley DA. 2000. The Sibley Guide to Birds. New York: Alfred A Knopf. p 340-341.

Shuford, W. D. and Gardali, T., eds. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento. <nrm.dfg.ca.gov/FileHandler.ashx?DocumentVersionID=19840>

Soule J. 1995 May 3. Ecology and Life History Edition. Comprehensive Species Report- Eremophila alpestris actia. NatureServe Explorer, Version 7.1. . Accessed 2010 Jul 20.

Yosef, R. 1996. Loggerhead Shrike (Lanius ludovicianus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. . Accessed 2010 Jul 20.

Zeiner, DC, Laudenslayer, Jr. WF, Mayer KE, and White M, eds. 1990. Range Map of the Loggerhead Shrike. California Wildlife Habitat Relationships System Life History & Range Maps. . Accessed 2010 Jul 20



Species Account Description: Kandis Gilmore & Emily Harvey
Каталог: cei -> documents -> galbreathsppaccts -> vertebrates
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