| Pink-headed Warbler | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Parulidae |
| Genus: | Ergaticus |
| Species: | E. versicolor |
| Binomial name | |
| Ergaticus versicolor (Salvin, 1864) |
|
| Range of Pink-headed Warbler | |
The Pink-headed Warbler (Ergaticus versicolor) is a small passerine bird found in the southwestern highlands of Guatemala and the central and southeastern highlands of the Mexican state of Chiapas. The adult is primarily red, with a silvery-pink head and chest. It is a fairly common to common resident of humid to semi-humid pine-oak, pine-evergreen and evergreen forest and edge, at altitudes ranging from 1,800–3,500 m (5,900–11,500 ft) above sea level.
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When Osbert Salvin first described the Pink-headed Warbler in 1864, he assigned it to the genus Cardellina — the same genus as that of the Red-faced Warbler. It was also briefly assigned to Setophaga, the genus of the American Redstart, before being moved to its current genus, Ergaticus, in 1881.[2] It is monotypic across its limited range, but forms a superspecies with the Red Warbler, which is found in the highlands of Mexico, north of the Isthmus of Tehuantepec. Despite disjunct populations and considerably different plumages, the two have sometimes been considered to be conspecific.[3]
The Pink-headed Warbler's common name is a reference to its most notable feature. The genus name Ergaticus is a Latinized version of the Ancient Greek ergatikos, meaning "willing to work",[4] while its specific name, versicolor, is Latin for "of changeable or various colors".[5] The latter is a reference to the warbler's changeable head color, which, depending on the angle of the viewer, looks either frosty pink or a deeper red than the rest of its body.[6] In Spanish, the species is called "Cabeza plateada" or "Silvery Head".[7]
The Pink-headed Warbler measures 12.5–13.5 cm (4.9–5.3 in) in length,[8][nb 1] and weighs 10 g (0.35 oz). Both sexes have a similar plumage, though females are, on average, slightly duller overall.[3] The adult has dark red upperparts, a silvery-pink chest and pinkish-red underparts. Its head is silvery-pink, with a reddish forehead, dusky lores[8] and dark brown irises.[10] Its bill is blackish, sometimes showing some horn color on the lower mandible, and its legs are flesh-colored.[8]
The juvenile is a rich brown with slightly paler underparts.[8] However, that plumage is quickly molted. By late summer, young birds are virtually indistinguishable from adults; only their unossified skulls distinguish them.[11]
The Pink-headed Warbler's call is high, thin, and somewhat metallic, variously transcribed as tsiu, ssing or tseeip.[3][8] Its song is a series of short trills and chips,[8] slower and less varied than that of the Red Warbler.[3] Only males sing.[6]
The Pink-headed Warbler is endemic to the highlands of central and eastern Chiapas in Mexico, and to western Guatemala.[7] It is a fairly common to common resident of humid to semi-humid pine-oak, pine-evergreen and evergreen forest and edge, at altitudes ranging from 1,800–3,500 m (5,900–11,500 ft) above sea level.[8] Though it prefers forest with dense, undisturbed understory, it is also found in disturbed forest with damaged understory in its strongholds in Guatemala; this is thought to be suboptimal habitat.[3] Though it is among the species expected to occur in El Salvador, it has not yet been reported there.[12]
The Pink-headed Warbler is an insectivore, gleaning insects and other invertebrates from vegetation (primarily in dense understory)[3] and making aerial sallies after flying prey.[13] It typically forages between 2–5 m (6.6–16 ft) off the ground, only seldom foraging above 7 m (23 ft) — except during the breeding season, when the male may hunt near the tops of trees from which it sings, as high as 15 m (49 ft) up.[13] The species often joins mixed species flocks that pass through its territory.[3] There is some evidence that volcanic eruptions, which can coat vegetation with thick ash and impact insect populations, cause declines in Pink-headed Warbler numbers.[8][13]
Pink-headed Warbler pairs remain together year-round. In the spring, the male begins singing on good weather days in early February and continues for the next several months, with song frequency peaking between March and May.[6] The female builds a domed nest made of pine needles and lined with moss. Built on the ground, it has a side entrance.[3] The female lays 2–4 eggs,[8] which she alone incubates for 16 days.[14] She spends some 71 percent of her time on the nest during incubation, in stints of 13–35 minutes (average 20.1 minutes) with breaks of 4–13 minutes (average 8.3 minutes).[15]
The young Pink-headed Warbler has a red mouth lining.[16]
The Pink-headed Warbler is currently rated as Vulnerable by the International Union for the Conservation of Nature,[1] while Mexico's government lists it as Endangered in that country.[17] Its population is decreasing, primarily because the cloud forest upon which it depends is becoming increasingly fragmented.[1]
In 1898, it was described as being "common on the highlands of central Chiapas".[18] However, in recent years it has become the least common of all wintering and resident warbler species in the highlands of northern Chiapas, based on point counts there.[19]