Hermit Warbler (Dendroica occidentalis) Potential Occurrence: Nesting Likely to Occur Status




Дата канвертавання25.04.2016
Памер11.66 Kb.
Aves (Birds): Passeriformes, Parulidae

Hermit Warbler (Dendroica occidentalis)

Potential Occurrence: Nesting Likely to Occur
Status: (Nesting)

Federal: none

State: none

Other: G4G5 S3



S
Photo: Steven Dowlan
pecies Description:
A small passerine bird, the Hermit Warbler has a yellow head with a short, pointed bill, black chin and throat, a grey back, and white underparts with black-streaked flanks (Sibley 2000). Males have a more prominent black chin than females and white wing-bars and tail spots (Pearson 1997).

Distribution: The Hermit Warbler is said to be a shy, reclusive bird, which is reflected in its common name (Sibley 2000). Its breeding range is in mountainous regions which extend from Cascade ranges in Washington to the San Bernardino Mountains of California in the south. It also inhabits the coastal regions where appropriate coniferous forest exists (Pearson 1997). It winters in the mountainous regions of Mexico to Nicaragua, but on occasion individuals have been seen during winter on the north coast of California from Del Norte County south to Tomales Bay (Pearson 1997; Green 1998).

Life History & Threats: Feeds by gleaning spiders and insects from foliage in the upper canopy. The Hermit Warbler builds its nest on a horizontal branch 25-125 feet above the ground and breeds from late April to early July with 3-5 eggs per clutch (Green 1998). In a study looking at effects of forest fragmentation on wildlife, this warbler was found to be sensitive to edges (Pearson 1997) which is consistent with its anecdotally shy nature.

Threats largely unstudied. Activities that degrade or eliminate coniferous forest canopy and insect prey would be detrimental. Threats include logging and development of forest habitats on breeding and wintering grounds, possible increase in exposure to brood parasitism by brown-headed cowbirds (Molothrus ater), and hybridization and possible competition with Townsend's warbler (Dendroica townsend) (From Paige 1999).



Habitat & Habitat Associations: In the coastal California mountains, the Hermit Warbler is most abundant in fir-dominated forest more than 300 years old (Raphael 1987)

Generally in upland coniferous forests with high canopy volume; shrub understories less important (Pearson 1997, AOU 1998). Prefers mature stands of pine and fir, with large trees and dense cover; prefers scattered groups of tall trees emergent from canopy (USDA Forest Service 1994). Douglas-fir (PSEUDOSTUGA MENZIESII) an important tree species throughout breeding habitat. Nests in older second-growth (> 40 yrs) and mature forests (> 120 yrs; Meslow and Wight 1975). (From NatureServe 2009)

Frequently found in association with the Yellow-Rumped Warbler (Dendroica coronata) (Hammerson 1994).

Conceptual Basis for GIS Model Development: We mapped suitable habitat as coniferous forest (i.e., Redwood-Douglas fir mix (Sequoia sempervirens-Pseudotsuga menziesii) or Pacific Douglas fir (Pseudotsuga menziesii var.menziesii) vegetation types). Possible best habitat was mapped as old growth areas with > 61 cm DBH.

Potential Occurrence in the Galbreath Wildlands Preserve: Hermit warblers were observed on the Preserve by Russ Landers (California Department Fish and Wildlife, Redding) Spring 2014. Protection status for this species applies to nesting individuals.

Habitat: Hermit Warblers nest in the canopy of older second and mature coniferous forests, particularly those with Douglas Fir. The quality of nesting habitat is good in the Preserve (Figure 90). Douglas-fir, an important species in breeding habitat, is found throughout coniferous forest on the Preserve. Older second growth forest (> 61 cm DBH) with Douglas Fir is most abundant in the northeast corner of the Preserve.

Nearest Occurrence:

Documented Occurrences in the Galbreath Wildlands Preserve: This species has not been documented 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.

Summary: Nesting Hermit Warblers are “Likely to Occur” in the Preserve. Good quality nesting is available in the Preserve and the species is a widespread breeder where appropriate habitat occurs.

References

Green M. 1990. Hermit Warbler. California Wildlife Habitat Relationships System Life History & Range Maps. . Accessed 2010 Jul 14.

Hammerson G. 1994 Mar 21. Ecology and Life History Edition. Comprehensive Species Report- Dendroica occidentalis. NatureServe Explorer, Version 7.1. . Accessed 2010 Jul 14.

Paige C. 1999 Mar 11. Management Information Edition. Comprehensive Species Report- Dendroica occidentalis. NatureServe Explorer, Version 7.1. . Accessed 2010 Jul 14.

Pearson SF. 1997. Hermit Warbler (Dendroica occidentalis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. . Accessed 2010 Jul 14.

Raphael MG. 1987. Estimating relative abundance of forest birds: simple versus adjusted counts. Wilson Bulletin. 99:125-131.

Sibley DA. 2000. The Sibley Guide to Birds. New York: Alfred A Knopf. p 438.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. Accessed 2010 Dec 28.



Photo info: Taken from CalPhotos database, copyright Steven Dowlan. For permission to use email owlhooter@aol.com. 2010 Jul 09.

Species Account Description: Kandis Gilmore & Emily Harvey


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