BIRD SPECIES AND DISTRIBUTIONS IN YUKON-CHARLEY RIVERS NATIONAL PRESERVE
Yellow Warbler (Dendroica petechia)
The family Parulidae is comprised of several New World genera (including Dendroica, Wilsonia, Vermivora, and Seiurus) collectively known as the wood warblers. Wood warblers are a numerous and diverse group of small, active and colorful songbirds. The name "warbler" means "singing with trills, runs and quavers" and was originally applied to European warbler species, unrelated to the North American wood warblers. Despite their namesake, wood warblers do not actually "warble." Rather, many species of this family may have several distinctive and cheerful songs. Almost entirely insectivorous, wood warblers use their slender, straight and pointed bills to capture prey. Members of the genus Dendroica (meaning "tree-dweller") include the Yellow, Townsend's and Yellow-rumped Warblers. A large group, this genus is primarily composed of arboreal warblers with wing bars and tail spots.
Descriptions: The Yellow Warbler primarily inhabits riparian thickets, particularly those with willow and alder. Named for its bright-yellow plumage, the Yellow Warbler has been referred to as the "wild canary." At 13cm, these small, plump birds are yellow overall, with short tails and prominent, dark eyes. Males have reddish streaks on their breasts that are faint or absent in the female. Two, bright-yellow wing bars highlight the yellowish-olive wings while the back and tail are solid yellow-olive. Yellow Warblers are the only yellow-breasted wood warbler with unique, yellow tail spots. While perched, these bright little birds may be seen frequently bobbing their tails!
Vocalizations: The song of the Yellow Warbler is a sweet, high and clear, "sweet, sweet, ti, ti, ti, to, soo" or "sweet, sweet, ti, ti, ti, to, swee," with variable upslurs and downslurs throughout. Their call is a clear, loud "chip" note. When on the fly, their call note is a clear, high, trilled "tzip."
Nests: Yellow Warblers typically construct compact, cup-shaped nests in low shrubs or thickets. Strongly woven of weed stalks, shredded bark, and grasses with finer materials lining the inside, the nests are soft havens for the 3-6, 16mm eggs of the clutch. As fastidious nest-builders, the females will at times steal nest materials from each other! Females produce one brood per year of off-white eggs, barely spotted to strongly blotched or wreathed in brown, olive, or gray speckles. Unaided, the female incubates the clutch for 11-12 days. Young birds fledge 9-12 days post-hatching and are reared by both parents.
Diet: The diet of the Yellow Warbler consists of insects gleaned from vegetation and bark. Occasionally, these wood warblers also consume berries. These birds also hawk flying insects by swooping after them from their high perches. Males are known to forage in higher and sparser trees than females, presumable to advertise their territorial ownership!
Distribution: The Yellow Warbler is a neotropical migrant, spending winters in the Bahamas and from northern Mexico south to Peru, Bolivia, and the Brazilian Amazon. In summer they range across most of Canada and the United States and south into Mexico. During the Yukon-Charley Rivers National Preserve Bird Inventory, June 1999 and 2000, Yellow Warblers were found at their highest density along the Yukon River Valley (YV), although they also were detected in the Little Black River Hills (LB), Ogilvie Foothills (OF), Three Fingers Subalpine Basin (TF), and Upper Charley Mountain Tundra (MT) ecological units. Only 21 birds were detected during the inventory and they were primarily heard in the shrubby riparian areas within the above ecological units.
|Density of Yellow Warblers by detailed ecological unit in Yukon-Charley Rivers National Preserve, Alaska, Avian Inventory, June 1999 and 2000.|