Yellow-rumped warbler

The yellow-rumped warbler was formally described in 1766 by the Swedish naturalist Carl Linnaeus in the twelfth edition of his Systema Naturae under the binomial name Motacilla coronata. The specific epithet is from Latin coronatus meaning "crowned". Linnaeus based his account on the "golden-crowned fly-catcher" that had been described and illustrated in 1760 by the English naturalist George Edwards using specimens that had been sent to him from Pennsylvania by the American naturalist William Bartram. The type locality was restricted to Philadelphia by the American Ornithologists' Union in 1910. The yellow-rumped warbler is now placed in the genus Setophaga that was introduced by the English naturalist William Swainson in 1827. The genus name Setophaga combines the Ancient Greek σης/sēs, σητος/sētos meaning "moth" with -φαγος/-phagos meaning "-eating". Since 1973, the American Ornithological Society has elected to merge the four forms above into one species. A 2017 proposal to split the yellow-rumped warbler into separate species failed. By contrast, the IOC World Bird List classifies the myrtle, Audubon's, and Goldman's as separate species (Setophaga coronata, Setophaga auduboni, and Setophaga goldmani, respectively), and the black-fronted warbler as a subspecies of S. auduboni. The bird's proper taxonomy remains a matter of debate. AviList, a recent attempt to harmonize competing taxonomies, provisionally retains Setophaga coronata as a single species pending further research into the contact zone between the myrtle and Audubon's forms. The myrtle form was apparently separated from the others by glaciation during the Pleistocene, and the Audubon's form may have originated more recently through hybridization between the myrtle warbler and the Mexican nigrifrons form. ==Distribution==

The yellow-rumped warbler breeds from eastern North America west to the Pacific, and southward from there into Western Mexico. Goldman's yellow-rumped warbler is a non-migratory endemic within the highlands of Guatemala, and the black-fronted warbler is a non-migratory Mexican endemic. Myrtle warblers migrate south for the winter, ranging from southern British Columbia all the way to Panama and throughout most of the southeastern United States. Audubon's warbler breeds throughout western North America, from British Columbia to California, across the Rocky Mountains and as far east as the Dakotas. Among warblers, the Audubon's is by far the most widespread in North America in winter, being among the last to leave in the fall and among the first to return in spring. ==Habitat==

Habitat in breeding range During the breeding season, the yellow-rumped warbler is generally known to be residing in either exclusively coniferous areas across the North American continent, or mixed coniferous-deciduous habitats where coniferous forests merge with trees like aspen (Populus spp.) and willow (Salix spp.), etc. Open areas preferred by the yellow-rumped warbler may include agricultural and residential areas, secondary forests, and shrublands, as these habitats generally do not have very dense vegetation; the species can also inhabit forests that are relatively open, such as mangroves, pine forests, and even coffee plantations. The yellow-rumped warbler tends to occupy more diversified habitats during the migration process; although it is sometimes found in the deserts of the American southwest, it is more commonly found in alpine areas during migration, as it tends to arid lowlands. ==Description==

The yellow-rumped warbler has an average length of 14 cm and weight of 12.5 g, its appearance is known to be different across its subspecies groups, especially the two major ones: the coronata group (myrtle warbler) and the auduboni group (Audubon's warbler); intra-group variations are also observed.). Yet the color of the coronata and auduboni groups' throat patches differs and distinguishes them, as the Audubon's warbler sports a yellow throat patch while the myrtle warbler has a white throat and eye stripe, and a contrasting black cheek patch. Females of both forms are more dull, with brown streaking front and back, but still have noticeable yellow rumps. Goldman's warbler, found in Guatemala, resembles Audubon's but has a white lower border to the yellow throat and otherwise darker plumage; males replace the slate blue of Audubon's with black. Comprising most of the species of the New World warbler family, among the genus Setophaga (formerly Dendroica), the yellow-rumped warbler is a mid-to-large sized species. The total length of the species can range from long, with a wingspan of . Although the length is only slightly greater than other Setophaga warblers, it can be mildly to significantly heavier than most other North American species, although blackpoll warblers are slightly larger still. Body mass can vary from , though averages between . Among standard measurements, the wing chord is , the tail is , the bill is and the tarsus is . ==Behavior==

Diet and foraging Audubon's and myrtle warblers are among North America's most abundant neotropical migrants. While they are primarily insectivorous, the species is perhaps the most versatile foragers of all warblers. Beyond gleaning from leaves like other New World warblers, they often flit, flycatcher-like, out from their perches in short loops, to catch flying insects. Other places yellow-rumped warblers have been spotted foraging include picking at insects on washed-up seaweed at the beach, skimming insects from the surface of rivers and the ocean, picking them out of spiderwebs, and grabbing them off piles of manure. Common foods include caterpillars and other larvae, leaf beetles, bark beetles, weevils, ants, scale insects, aphids, grasshoppers, caddisflies, craneflies, and gnats, as well as spiders. They also eat spruce budworm, a serious forest pest, during outbreaks. When bugs are scarce, the myrtle warbler also eats fruit, including the wax-myrtle berries which gave the myrtle subspecies its name. It is the only warbler able to digest such waxy material. The ability to use these fruits allows it to winter farther north than other warblers, sometimes as far north as Newfoundland. Other commonly eaten fruits may include juniper berries, poison ivy, poison oak, greenbrier, grapes, Virginia creeper and dogwood. They eat wild seeds such as from beach grasses and goldenrod, and they may come to feeders, where they'll take sunflower seeds, raisins, peanut butter, and suet. On their wintering grounds in Mexico they've been seen sipping the sweet honeydew liquid excreted by aphids. Male yellow-rumped warblers tend to forage higher in the trees than females do. While foraging with other warbler species, they sometimes aggressively displace other species, including pine warblers and Blackburnian warblers. Nesting and vocal behaviors Audubon's and the myrtle nest in coniferous and mixed woodlands, and lay 4–5 eggs. Females build the nest, sometimes using material the male carries to her. The nest is a cup of twigs, pine needles, grasses, and rootlets. She may also use moose, horse, and deer hair, moss, and lichens. She lines this cup with fine hair and feathers, sometimes woven into the nest in such a way that they curl up and over the eggs. The nest takes about 10 days to build. Nests are located on the horizontal branch of a conifer, anywhere from high. Tree species include hemlock, spruce, white cedar, pine, Douglas-fir, and larch or tamarack. They may build their nests far out on a main branch or tuck it close to the trunk in a secure fork of two or more branches. Occasionally nests are built in a deciduous tree such as a maple, oak or birch. The eggs are incubated for 12 to 13 days. Nestlings are helpless and naked at hatching but grow quickly. The young are brooded for 10 to 14 days, at which point they can fledge. The yellow-rumped warbler has a trill-like song of 4–7 syllables ('') and an occasional check or chip'' call note. ==References==