Tuesday, February 3, 2009
Wilson’s Warbler: Abundant, Yet Vulnerable
You might think the Wilson’s Warbler is one of the most abundant warbler species while traveling through Alaska, most of Canada, and south through the western USA to southern California and New Mexico. Your supposition would largely be correct.
But long-term trend analysis indicate recent population declines, especially in the western portion of the species’ range. The most likely problem is large-scale destruction of riparian habitat.
Nesting on or near the ground at elevations that vary from sea level to the alpine zone, the three subspecies of Wilson’s Warbler encompass a wide geographical area that spans from eastern Canada to Alaska and portions south into Utah, New Mexico and central California.
Interestingly, the subspecies may occur together in non-breeding range, with all three subspecies possible in Panama.
Although it shares its genus name – Wilsonia -- with other wood-warbler species – (Canada and Hooded), Wilson’s is by far the most common. All three species possess rectal bristles (small , highly-sensitive feathers at the base of the bill) that are utilized during “flycatching,” a foraging behavior that can sometimes help with field identification.