This article's lead sectionmay be too short to adequately summarize the key points. Please consider expanding the lead to provide an accessible overview of all important aspects of the article.(July 2018)
The genus name Setophaga is from Ancient Greekses, "moth", and phagos, "eating", and the specific petechia is from Italian petecchia, a small red spot on the skin.[2]
Description and taxonomy
Other than in male breeding plumage and body size, all warblersubspecies are very similar. Winter, female and immature birds all have similarly greenish-yellow uppersides and are a duller yellow below. Young males soon acquire breast and, where appropriate, head coloration. Females are somewhat duller, most notably on the head. In all, the remiges and rectrices are blackish olive with yellow edges, sometimes appearing as an indistinct wing-band on the former. The eyes and the short thin beak are dark, while the feet are lighter or darker olive-buff.[3][4]
The 35 subspecies of S. petechia can be divided into three main groups according to the males' head color in the breeding season.[4] Each of these groups is sometimes considered a separate species, or the aestiva group (yellow warbler) is considered a species different from S. petechia (mangrove warbler, including golden warbler); the latter option is the one currently accepted by the International Ornithological CongressWorld Bird List.[5]
Depending on subspecies, the yellow warbler may be between 10 and 18cm (3.9 and 7.1in) long, with a wingspan from 16 to 22cm (6.3 to 8.7in). They weigh 7–25g (0.25–0.88oz), varying between subspecies and whether on migration or not, globally averaging about 16g (0.56oz) but only 9–10g (0.32–0.35oz) in most breeding adults of the United States populations. Among standard measurements throughout the subspecies, the wing chord is 5.5 to 7cm (2.2 to 2.8in), the tail is 3.9 to 5.6cm (1.5 to 2.2in), the bill is 0.8 to 1.3cm (0.31 to 0.51in) and the tarsus is 1.7 to 2.2cm (0.67 to 0.87in).[4] The summer males of this species are generally the yellowest warblers wherever they occur. They are brilliant yellow below and greenish-golden above. There are usually a few wide, somewhat washed-out rusty-red streaks on the breast and flanks. These markings are the reason for the scientific name petechia, which roughly translates to "liver spotted".[6] The subspecies in this group mostly vary in brightness and size according to Bergmann's and Gloger's Rule.[7]
The golden warbler (petechia group; 17 subspecies[4]) is generally resident in the mangrove swamps of the West Indies. Local seasonal migrations may occur. On the Cayman Islands for example, S. p. eoa was found to be "decidedly scarce" on Grand Cayman and apparently absent from Cayman Brac in November 1979, while it had been a "very common" breeder in the group some ten years before, and not frequently seen in the winters of 1972/1973; apparently, the birds disperse elsewhere outside the breeding season. The Cuban golden warbler (S. p. gundlachi) barely reached the Florida Keys where it was first noted in 1941, and by the mid-20th century a breeding population was resident.[8] Though individual birds may stray farther north, their distribution is restricted by the absence of mangrove habitat.
They are generally smallish, usually weighing about 10g (0.35oz) or less and sometimes[9] as little as 6.5g (0.23oz). The summer males differ from those of the yellow warbler in that they have a rufous crown, hood or mask. The races in this group vary in the extent and hue of the head patch.
The mangrove warbler (erithachorides group; 12 subspecies[4]) tends to be larger than other yellow warbler subspecies groups, averaging 12.5cm (4.9in) in length and 11g (0.39oz) in weight. It is resident in the mangrove swamps of coastal Middle America and northern South America; S. p. aureola is found on the oceanic Galápagos Islands.[4] The summer males differ from those of the yellow warbler in having a rufous hood or crown. The races in this group vary in the extent and hue of the hood, overlapping extensively with the golden warbler group in this character.[4]
The American yellow warbler (aestiva group; 6 subspecies)[4] breeds in the whole of temperateNorth America as far south as central Mexico in open, often wet, woods or shrub. It is migratory, wintering in Central and South America. They are very rare vagrants to western Europe[3] and Scandinavia[10]
Resident adult male mangrove warbler S. p. bryanti, Quepos, Costa Rica
Breeding male golden warbler S. p. petechia, Washington-Slagbaai National Park, Bonaire, (Netherlands Antilles)
Breeding male mangrove warbler S. p. aureola, Puerto Ayora, Santa Cruz (Galápagos Islands)
The song is a musical strophe that can be rendered sweet sweet sweet, I'm so sweet, although it varies considerably between populations. The call is a soft or harder chip or ship. This is particularly frequently given by females after a male has finished his song. In territorial defense, they give hissing calls, while seet seems to be a kind of specialized cowbird alert (see below). Other calls are given in communication between pair-members, neighbors, or by young begging for food. These birds also communicate with postures and perhaps with touch.[3]
American yellow warblers breed in most of North America from the tundra southwards, except for the far Southwest and the Gulf of Mexico coast.[3] American yellow warblers winter to the south of their breeding range, from southern California to the Amazon region, Bolivia and Peru.[3] The mangrove and golden warblers occur to the south of it, to the northern reaches of the Andes.
American Yellow Warblers arrive in their breeding range in late spring – generally about April/May – and move to winter quarters again starting as early as July, as soon as the young are fledged. Most, however, stay a bit longer; by the end of August, the bulk of the northern populations has moved south, though some may linger almost until fall. At least in northern Ohio, yellow warblers do not linger, leaving as they did 100 years ago.[11]
The breeding habitat of American yellow warblers is typically riparian or otherwise moist land with ample growth of small trees, in particular willows (Salix). The other groups, as well as wintering birds, chiefly inhabit mangrove swamps and similar dense woody growth. Less preferred habitat are shrubland, farmlands and forest edges. In particular American yellow warblers will come to suburban or less densely settled areas, orchards and parks, and may well breed there. Outside the breeding season, these warblers are usually encountered in small groups, but while breeding they are fiercely territorial and will try to chase away any conspecific intruder that comes along.[3]
Roughly 60% of their diet is caterpillars. They also consume wasps,[12] mayflies, moths, mosquitoes, beetles, damselflies, treehoppers, other insects,[13] insect larvae, and spiders.[14] They acquire prey by gleaning in shrubs and on tree branches, and by hawking prey that tries to fly away. Other invertebrates and some berries and similar small juicy fruits[15] are also eaten, the latter especially by American yellow warblers in their winter quarters. The yellow warbler is one of several insectivorous bird species that reduce the number of coffee berry borer beetles in Costa Rica coffee plantations by 50%. Caterpillars are the staple food for nestlings, with some – e.g. those of geometer moths (Geometridae) – preferred over others.[16]
The predators of yellow and mangrove warblers are those typical of such smallish tree-nesting passerines, such as snakes, foxes, birds of prey, and many others. The odds of an adult American yellow warbler surviving from one year to the next are on average 50%; in the southern populations, by contrast, about two-thirds of the adults survive each year. Conversely, less than one American yellow warbler nest in three on average suffers from predation in one way or another, while two out of three mangrove and golden warbler nests are affected.[17]
These New World warblers seem to mob predators only rarely. An exception are cowbirds, which are significant brood parasites. The yellow warbler is a regular host of the brown-headed cowbird (Molothrus ater), with about 40% of all nests suffering attempted or successful parasitism. By contrast, the tropical populations are less frequent hosts to the shiny cowbird (M. bonariensis), with only 10% of nests affected. This may be due to the slightly larger size of shiny cowbirds, which are less likely to survive being fed by the much smaller warbler, compared to brown-headed cowbirds.[20] The yellow warbler is one of the few passerine proven to be able to recognize the presence of cowbird eggs in its nest.[20] Upon recognizing one the warbler will often smother it with a new layer of nesting material. It will usually not try to save any of its own eggs that have already been laid, but produce a replacement clutch. Sometimes, the parents desert a parasitized nest altogether and build a new one. Unlike some cuckoos, cowbird nestlings will not actively kill the nestlings of the host bird; mixed broods of Setophaga and Molothrus may fledge successfully.[17] However, success of fledging in yellow warbler nests is usually decreased by the parasitism of cowbirds due to the pressures of raising a much larger bird.[20]
Other than predation, causes of mortality are not well known. The maximum recorded ages[21] of wild yellow warblers are around 10 years. A wintering American yellow warbler examined near Turbo, Colombia was not infected with blood parasites, unlike other species in the study. It is unclear whether this significant, but wintering birds in that region generally lacked such parasites.[22]
Breeding
Yellow warbler nest with small clutch
As usual for members of the Parulidae, yellow warblers nest in trees, building a small but very sturdy cup nest. Females and males rear the young about equally, but emphasize different tasks: females are more involved with building and maintaining the nest, and incubating and brooding the offspring. Males are more involved in guarding the nest site and procuring food, bringing it to the nest and passing it to the waiting mother, which does most of the actual feeding. As the young approach fledging, the male's workload becomes proportionally higher.[3]
A breeding pair of yellow warblers. The female (right) is carrying nesting material.
The American yellow and mangrove (including golden) warblers differ in some other reproductive parameters. While the former is somewhat more of an r-strategist, the actual differences are complex and adapted to different environmental conditions. The yellow warbler starts breeding in May/June, while the mangrove warbler breeds all year round. American yellow warblers have been known to raise a brood of young in as little as 45 days, with 75 the norm. Tropical populations, by contrast, need more than 100 days per breeding. Males court the females with songs, singing 3,200 or more per day. They are, like most songbirds, generally serially monogamous; some 10% of mangrove warbler and about half as many American yellow warbler males are bigamous. Very few if any American yellow warblers breed more than once per year, with just 5% of female mangrove warblers doing so. If a breeding attempt fails, either parent will usually try to raise a second brood.[17]
The clutch of the American yellow warbler is 3–6 (typically 4–5, rarely 1–2) eggs. Incubation usually takes 11 days, sometimes up to 14. The nestlings weigh 1.3g (0.046oz) on average, are brooded for an average 8–9 days after hatching, and leave the nest the following day or the one thereafter. The mangrove warbler has only 3 eggs per clutch on average and incubates some 2 days longer. Its average post-hatching brooding time is 11 days. Almost half of the parents (moreso in the mangrove warbler than the American yellow warbler) attend the fledglings for two weeks or more after these leave the nest. Sometimes the adults separate early, each accompanied by one to three of the young.[23]
Some 3–4 weeks after hatching, the young are fully independent of their parents. They become sexually mature at one year of age, and attempt to breed right away. Some 55% of all American yellow warbler nestings are successful in raising at least one young.[23] In contrast, only 25% of mangrove warbler nests successfully fledge any offspring, with accidents and predation frequently causing total loss of the clutch.
Status and conservation
Yellow warblers, in particular the young, devour many pestinsects during the breeding season. The plumage and song of the breeding males have been described[3] as "lovely" and "musical", encouraging ecotourism. No significant negative effects of American yellow and mangrove warblers on humans have been recorded.[3]
Being generally common and occurring over a wide range, the yellow warbler is not considered a threatened species by the IUCN.[24] Some local decline in numbers has been found in areas, mainly due to habitat destruction and pollution. The chief causes are land clearance, the agricultural overuse of and herbicide and pesticide, and sometimes overgrazing. However, stocks will usually rebound quickly if riparian habitat is allowed to recover, particularly among the prolific American yellow warbler.[1][3]
The North American populations are legally protected by the Migratory Bird Treaty Act. The Barbados golden warbler[25] (D. p. petechia) has been listed as "endangered foreign wildlife" by the United States' Endangered Species Act (ESA) since 1970; other than for specially permitted scientific, educational or conservation purposes, importing it into the USA is illegal. The Californian yellow warbler (D. p./a. brewsteri) and Sonoran yellow warbler (D.p./a. sonorana) are listed as "species of concern" by the ESA.[26]
↑ Yezerinac, S. M., & Weatherhead, P. J. (1997). Extra–pair mating, male plumage coloration and sexual selection in yellow warblers (Dendroica petechia). Proceedings of the Royal Society of London. Series B: Biological Sciences, 264(1381), 527-532.
The brown-headed cowbird is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or April.
The myrtle warbler is a small New World warbler. It is considered a subspecies of the yellow-rumped warbler and its own species by different classification societies. The myrtle warbler has a northerly and easterly distribution, with the Audubon's warbler further west. It breeds in much of Canada and the northeastern United States. It is migratory, wintering in the southeastern United States, eastern Central America, and the Caribbean. It is a rare vagrant to western Europe, and has wintered in Great Britain.
The yellow-rumped warbler is a regular North American bird species that can be commonly observed all across the continent. Its extensive distribution range connects both the Pacific and Atlantic coasts of the U.S. as well as Canada and Central America, with the population concentrating in the continent's northern parts during the breeding season and migrating southwards to southern North and Central America in Winter. The species generally prefers coniferous forests or mixed coniferous-deciduous forests as its breeding habitat, while during the winter it can be found inhabiting more open areas such as shrublands that offer food resources. The diet of the yellow-rumped warbler is based primarily on insects, though the species does eat fruits such as juniper berries as well, especially in winter.
Audubon's warbler is a small bird of the family Parulidae. At one time considered a distinct species, discovery of a hybrid zone between it and the myrtle warbler in 1973 has led to it being classified as a subspecies of the yellow-rumped warbler.
The Cape May warbler is a species of New World warbler. It breeds in northern North America. Its breeding range spans all but the westernmost parts of southern Canada, the Great Lakes region, and New England. It is migratory, wintering in the West Indies. This species is a very rare vagrant to western Europe, with two records in Britain as of October 2013. The English name refers to Cape May, New Jersey, where George Ord collected the specimen later described by Alexander Wilson. This species was not recorded again in Cape May for another 100 years, although it is now known as an uncommon migrant there.
The Blackburnian warbler is a small New World warbler. They breed in eastern North America, from southern Canada, westwards to the southern Canadian Prairies, the Great Lakes region and New England, to North Carolina.
The blackpoll warbler is a New World warbler. Breeding males are mostly black and white. They have a prominent black cap, white cheeks, and white wing bars. The blackpoll breeds in forests of northern North America, from Alaska throughout most of Canada, to the Adirondack Mountains of New York as well as New England in the Northeastern United States. They are a common migrant throughout much of North America. In fall, they fly south to the Greater Antilles and the northeastern coasts of South America in a non-stop long-distance migration over open water, averaging 2,500 km (1,600 mi), one of the longest-distance non-stop overwater flights ever recorded for a migratory songbird. Rare vagrants to western Europe, they are one of the more frequent transatlantic passerine wanderers.
The chestnut-sided warbler is a New World warbler. They breed in eastern North America and in southern Canada westwards to the Canadian Prairies. They also breed in the Great Lakes region and in the eastern United States.
The magnolia warbler is a member of the wood warbler family Parulidae.
The black-and-white warbler is a species of New World warbler, and the only member of its genus, Mniotilta. It breeds in northern and eastern North America and winters in Florida, Central America, and the West Indies down to Peru. This species is a very rare vagrant to western Europe.
The hooded warbler is a New World warbler. It breeds in eastern North America across the eastern United States and into southernmost Canada (Ontario). It is migratory, wintering in Central America and the West Indies. Hooded warblers are very rare vagrants to western Europe.
The American redstart is a New World warbler. It is unrelated to the Old World (common) redstart.
The black-throated green warbler is a small songbird of the New World warbler family.
The cerulean warbler is a small songbird in the family Parulidae. It is a long-distance migrant, breeding in eastern North American hardwood forests. In the non-breeding season, it winters on the eastern slope of the Andes in South America, preferring subtropical forests.
The prairie warbler is a small songbird of the New World warbler family.
The palm warbler is a small songbird of the New World warbler family.
Kirtland's warbler, also known in Michigan by the common name jack pine bird, or the jack pine warbler, is a small songbird of the New World warbler family (Parulidae). Nearly extinct just 50 years ago, populations have recovered due to the conservation efforts of Phil Huber and the U.S. Forest Service. It requires large areas, greater than 160 acres, of dense young jack pine for its breeding habitat. This habitat was historically created by wildfire, but today is created through the harvest of mature jack pine, and planting of jack pine seedlings.
The yellow-throated warbler is a small migratory songbird species in the New World warbler family (Parulidae) found in temperate North America.
The golden-cheeked warbler is an endangered species of bird that breeds in Central Texas, from Palo Pinto County southwestward along the eastern and southern edge of the Edwards Plateau to Kinney County. The golden-cheeked warbler is the only bird species with a breeding range endemic to Texas.
The shiny cowbird is a passerine bird in the New World family Icteridae. It breeds in most of South America except for dense forests and areas of high altitude such as mountains. Since 1900 the shiny cowbird's range has shifted northward, and it was recorded in the Caribbean islands as well as the United States, where it is found breeding in southern Florida. It is a bird associated with open habitats, including disturbed land from agriculture and deforestation.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
