Wilsons Warbler
[order] PASSERIFORMES | [family] Parulidae | [latin] Wilsonia pusilla | [UK] Wilsons Warbler | [FR] Sylvette a calotte noire | [DE] Monchs-Waldsanger | [ES] | [NL] Wilsons Zanger
Subspecies
| Genus | Species | subspecies | Breeding Range | Breeding Range 2 | Non Breeding Range |
| Wilsonia | pusilla | NA | w, n | MA | |
| Wilsonia | pusilla | chryseola | |||
| Wilsonia | pusilla | pileolata | |||
| Wilsonia | pusilla | pusilla |
Physical charateristics
About 10% smaller than Hooded Warbler with proportionately shorter, finer bill; close in size to Yellow Warbler. Quite small, animated, willow-loving Nearctic wood warbler, with bright olive-green upperparts and lemon-yellow underparts; male has black cap; no white in tail.
Listen to the sound of Wilsons Warbler
[audio:http://www.aviflevoland.nl/sounddb/W/Wilsons Warbler.mp3]
Copyright remark: Most sounds derived from xeno-canto
| wingspan min.: | 15 | cm | wingspan max.: | 17 | cm |
| size min.: | 11 | cm | size max.: | 12 | cm |
| incubation min.: | 11 | days | incubation max.: | 13 | days |
| fledging min.: | 9 | days | fledging max.: | 13 | days |
| broods: | 1 | eggs min.: | 3 | ||
| eggs max.: | 6 |
Range
North America : West, North
Habitat
Breeds almost throughout Nearctic climatic zones, from Arctic tundra and montane valleys and slopes in Alaska, and up to nearly 500 m in southern California. Favours moist open shrubbery, including willow and dwarf birch, especially by streams, ponds, and bogs. On migration, more tolerant of drier situations.
Reproduction
Wilson’s Warblers are primarily monogamous, although some are polygynous, and high rates of extra-pair copulations have been observed. Pacific Lowland populations lay fewer eggs, raise fewer young, and have higher rates of monogamy than populations in the mountains. Lowland populations nest in shrubs, unlike their ground-nesting highland relatives. The female selects the nest site, either sunken in a patch of moss or sedge, or in a low shrub or vine. She builds a bulky open cup of leaves, grass, and moss, lined with grass and hair. The female incubates 2 to 7 eggs for 11 to 13 days, and broods the young for the first few days after they hatch. Both parents feed the young, which leave the nest 9 to 11 days after hatching. The parents continue to feed the young for up to 25 days after they fledge.
Feeding habits
Wilson’s Warblers eat insects and other small invertebrates. They also sometimes eat berries.
Conservation
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Migration
Migratory, moving at least 800 km (most birds over 2500 km) between summer and winter ranges. Winter range (Mexico and southern Texas south to Panama) very limited in comparison with breeding range; highest numbers in Mexico. Migration on broad front in both seasons, mainly west of Appalachians, with most birds skirting Gulf of Mexico to west rather than overflying it; uncommon to rare in south-east states and West Indies. A few vagrant records July-September in Arctic Canada and Alaska, on islands in Bering Sea, and in Greenland.
Distribution map
