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"In his plumes dwells the gold of the sun, in his voice its brightness and good cheer. We have not to seek him in the depths of the forest, the haunt of nearly all his congeners, he comes to us and makes his home near ours."
- Arthur Cleveland Bent, quoting a Dr. Chapman.

Identification
These little warblers (4 3/4 inches (12 cm.)) are yellow underneath and green to yellow-green above. Males have chestnut streaks on their breast while females usually have none at all. All ages and sexes have a very faint yellow eyering and yellow spots on the inner webs of the rectrices, that's to say the vanes of the tail feathers towards the tail's center.

Subspecies
The Yellow Warbler has numerous subspecies since it is one of the most widespread of North American warblers. The subspecies are divided into three groups, which were formerly treated as separate species. The Golden Warblers (Dendroica petechia petechia group) occurs in the Caribbean; its males often possess chestnut caps and first fall/first spring females are gray above and whitish below. Mangrove Warblers (D. p. erithacorides group), found from northern Mexico to western South America, have been recorded in Texas. Adult males have completely chestnut heads and first spring males have chestnut auricular patches (sides of the face). Even the females may have chestnut caps. The typical Yellow Warblers of North America belong to the Migratory Northern Yellow Warbler group, D. p. aestiva, and are as described above in the Identification Section.

Within the aestiva group, the subspecies occurring at Andrew Molera State Park is D. p. brewsteri.

Range
The Northern Yellow Warblers are neotropical migrants that breed within North America and winter from Mexico to northern South America. Within North America they breed throughout most of Alaska and Canada and the lower 48 States except for Texas and the extreme south and southeast. The subspecies of Northern Yellows are morcomi in the Rocky Mountains, parkesi and amnicola in Canada east of the Rockies, aestiva in the US and southernmost Canada east of the Rockies, rubiginosa in coastal British Columbia and the Alaska Panhandle, and brewsteri in the Pacific Northwest and California.

The Mangrove and Golden Warblers are residents within their ranges and will be spoken of no further here.

Song
The song is very rapid and varies, but has been likened to sweet-sweet-sweet-I'm-so-sweet or sweet-sweet-sweet-little-more-sweet.

Banding History
Yellow Warblers breed in Monterey County but not at Andrew Molera State Park. It is believed to require sufficiently hot summers and to not prefer the moist fog-shrouded drainages of the Big Sur River running through Andrew Molera. At the Big Sur Ornithology Lab, Yellow Warblers are a frequently captured spring and fall migrant, coming north through Andrew Molera from early May to June and again south from mid-August to late October. The Big Sur Ornithology Lab has banded 2025 of 2398 Yellow Warblers captured.

Habits
Yellow WarblerYellow Warblers nest in shrubby growth by swamps and watercourses, in wet scrub, tree foliage, mangroves, gardens, shrubberies and berry patches. Dense growth may be preferred in order to reduce nest predation and brood parasitism. The males are sometimes polygamous. The female builds a neat, compact cup nest in an upright twig fork 2 to 12 feet up, sometimes up to 40 or even 60 feet. The cup is made of wool, plant down, dry weed stem fibers, and fine grass stems, then lined with plant fibers, cotton, plant down, and sometimes feathers. Incubation of the 3 to 6 (usually 4 or 5) whitish spotted eggs is for 11 days. Both parents tend the nestlings until fledging occurs at 9 to 12 days.

Status
The Yellow Warbler is not a threatened or endangered species. In California however, the coastal brewsteri subspecies has been declining due to the loss of riparian thickets in that region and probably also to brood parasitism by Brown-headed Cowbirds.

A coalition of public and private organizations called Partners in Flight (PIF) is trying to reverse the population declines of many North American Songbirds. The California chapter of PIF has produced a document called the California Riparian Habitat Conservation Plan, which outlines suggestions for restoring California's riparian bird species by preserving and actively restoring riparian habitats and reducing the impacts of human industry and brood parasitism. The Plan is completely voluntary.

The Yellow Warbler is a focal species in this Plan, that being one of a few selected indicator species whose populations may be intensively monitored to assess the health of a particular ecosystem. Economy of effort is the rationale behind monitoring a few carefully selected focal species: if the ecosystem is largely healthy, the populations of many more unmonitored species are probably healthy as well.

- Lionel Leston

References

Baicich, P and CJO Harrison, eds. 1997. 2nd ed. A Guide to the Nests, Eggs and Nestlings of North American Birds. Natural World Academic Press.

Bent, AC. 1963. Life Histories of North American Wood Warblers - Volume 1. Dover Publications, Inc.

Big Sur Ornithology Lab Database 1992-2000.

California Partners in Flight, 1999. Riparian Habitat Conservation Plan - A strategy for arresting the decline of bird species in California. http://www.prbo.org/CPIF/Riparian/Specplans.html

Dickinson, MB, ed. 1999. 3rd ed. Field Guide to the Birds of North America. National Geographic Society.

Dunn, J and K Garrett 1997. A Field Guide to Warblers of North America. Houghton Mifflin Company, Boston.

Peterson, RT, 1992. 2nd ed. A Field Guide to Western Bird Songs - Cornell Laboratory of Ornithology Interactive Audio. Houghton-Mifflin Company.

Roberson, D and C Tenney, eds. 1993. Atlas of the Breeding Birds of Monterey County, California. Monterey Peninsula Audubon Society.

VWS Featured Birds:
Townsend's Warbler
Yellow Warbler
Flycatcher
Warbling Vireo
Wilson's Warbler