Warblers, according to one classic old bird book — 1897’s “Bird Neighbors” by Neltje Blanchan — are a family of birds characterized as “exceedingly active, graceful, restless feeders among the terminal twigs of trees and shrubbery” that are nonetheless “strangely unknown to all but devoted bird lovers.” This still rings true today: many a devoted bird lover seeks out warblers with an eagerness incomprehensible to the uninitiated, while the average human being lives in ignorance of these colorful co-residents of our world. Let’s try to bridge this gap a little.
A few basics: Warblers are small songbirds usually adorned with yellow plumage, sometimes all over, sometimes in sparser highlights. While many species have some level of “warbling” song, they are not in truth among the most spectacular singers of the avian world. Their “active” and “restless” nature points to their feeding style and therefore dietary preferences — warblers mostly eat bugs, which they pursue in trees, plucking them from twig tips and reaching under leaves. This preference for insect food is suggestive of their general migratory tendency. Warblers are mostly what are known as “neotropical migrants,” with most species spending their winters in Mexico and Central America and only moving north to the United States and Canada for the summer breeding season.
A few clarifications: First, while warblers are, across the continent, mostly birds of spring and summer, California is a little bit special in the mildness of our winters. This means that we have a few winter warblers as well: the hardy yellow-rumped warbler, the beautiful Townsend’s warbler, and the odd, non-tree-dwelling common yellowthroat, which can be found in our wetlands all year round. Today, I will focus more on our springtime migrants, which are more representative of the general warbler pattern across the country.
Second, warblers are not goldfinches, our far more common and obvious little yellow birds. Goldfinches are flocking seed-eaters that come readily to backyard bird feeders. Warblers essentially are not feeder visitors (the winter warblers may come occasionally to feeders in winter, when bugs are scarce), and never sit placidly at a seed feeder as they patiently chow down. Remember, warblers are active, restless tree-dwellers.
So, what are our winter warbler species and where can you see them? Perhaps the best place to start is with the striking and elegant Wilson’s warbler, which wears a crisp black cap to add variety to an overall plumage of the brightest imaginable yellow. Not only are they the most visually striking of our summer warblers, they are also relatively abundant and easy to encounter. You can find Wilson’s warblers in moist coniferous forests and dense broadleaf woodlands, especially near creeks. While they are hard to miss once they come close, you might first detect their presence by their simple song: a string of repeated notes that accelerates for a few seconds before ending abruptly.
The other clearly prominent representative of Marin’s spring and summer warblers is the orange-crowned warbler. Despite the somewhat flashy promise of their name, this is a much lower-profile bird than Wilson’s warbler in terms of visual appearance. Their orange crown is almost always invisible and their overall yellow plumage is far more muted than that of Wilson’s warblers — think of female lesser goldfinches compared to breeding male American goldfinches, if you are familiar with those more common feeder birds. Orange-crowns are common but easily overlooked breeders in both woodland and scrubby habitats. Although their song is most prominent in early spring, you may still hear it occasionally: a fairly steadily paced and dry trill, quite similar to that of dark-eyed juncos, with one unique feature — they typically drop down in pitch about halfway through and so are performed on precisely two different pitches.
Wilson’s and orange-crowned warblers are by far our most common spring warblers. The aforementioned and unusual common yellowthroat maintains a year-round presence in salt marshes, while yellow warblers are common passing migrants but scarce breeders along creeks. A visit to the Douglas fir forests near Rock Spring is worth a special trip to seek out Marin’s small population of breeding yellow-rumped warblers and the elegantly striped black-throated gray warbler.
“Devoted bird lovers,” Blanchan wrote, seek out warblers “during those months that particularly favor acquaintance.” Warblers are here now, if you seek them out.
Jack Gedney’s On the Wing runs every other Monday. He is a co-owner of Wild Birds Unlimited in Novato and author of “The Private Lives of Public Birds.” You can reach him at jack@natureinnovato.com.
