The tiny, bright yellow bird that John James Audubon called “Wilson’s Flycatching Warbler” breeds in a large swath all across northern North America. Wilson’s Warblers winter in much of Central America, and so pass through most of the continent at some point during the year. Molecular studies have shown that certain breeding populations winter in specific geographic areas. For instance, the most northerly-breeding birds of the western population winter the furthest south in Central America.
One of the original names of Wilson’s Warbler was “Pileolated Warbler” after the male’s striking black skullcap, or pileum. As one of the warblers that has a flattish bill bordered by specialized feather “whiskers” to aid in the capture of small insects, the descriptor of “flycatching” or “flycatcher” was added to its name several times through history. Because he was the first to formally publish a description, ornithologist Alexander Wilson is now honored in the common name.
In the breeding season, the typical habitat of Wilson’s Warblers is dense thickets, especially moist ones in riparian areas. In the winter, however, it can be found in a much wider variety of habitats, which are often more open than nesting habitats. It is most abundant in tropical forests, cloud forest, pine-oak forest, and forest edge habitat, and is frequently found on coffee farms.
While many bird species tend to be somewhat set in their behavior at certain times of the year, wintering Wilson’s Warblers may be solitary, either roaming through a locality or forming a territory, or found in mixed flocks of other birds. In addition to insects and some fruit, nectar is also consumed in winter. This flexibility in habitat requirements, behavior, and food resources has no doubt contributed to the success of Wilson’s Warblers, which remain one of our most common warblers. Yet recent population trends indicate numbers have declined 2% a year in the U.S., and over 4% a year in the eastern U.S. in recent decades. This is a well-studied species, but we need to know more to understand how to best conserve them. Unfortunately, we often neglect to take action with common species until serious problems are evident.
We have found Wilson’s Warblers common on coffee farms we visited in Panama and Nicaragua. We are about to travel once again to Nicaragua, where we will spend time at Finca El Jaguar in Jinotega, and once again visit to Finca Esperanza Verde in San Ramon, Matagalpa. You’ll be hearing more about our trip soon!