neighborhood naturalist CORVALLIS, OREGON — SPRING 2017
Lesser Goldfinch article and photography by Lisa Millbank
T
he Lesser Goldfinch is essentially a Southwestern bird, at home in open pine-oak woodlands and rolling foothill rangelands. Few nineteenth-century ornithologists documenting Oregon’s birds reported Lesser Goldfinches, so they may be relative newcomers to the Northwest. Bird feeders, irrigation and development may have enabled these tiny finches to expand their range northward to Washington. On the other hand, it’s possible that Lesser Goldfinches were always in Oregon, but were overlooked by most early naturalists. Distinguishing them from American Goldfinches isn’t always easy. The two color patterns of adult males—“black-backed” in the eastern part of their range, and “green-backed” in the West—might have confused things further. An adult male Lesser Goldfinch from our area has a black cap, olive back and yellow underparts. His black wings and tail are marked with white patches. His American Goldfinch counterpart has two adult male plumages, bold yellow and black for the breeding season, and a much more subdued look for fall and winter. Females and juveniles of both species, as well as nonbreeding male American Goldfinches, are all similar in appearance.
and the presence or absence of a white patch on the wings usually is sufficient to identify them. Perhaps the easiest way to tell them apart is by listening to their calls. The Lesser Goldfinch gives a rough chig-chig-chig call and a variety of sweet, plaintive notes often described as “kitten-like” in field guides. Both goldfinch species are excellent singers, but the male Lesser Goldfinch has a hidden talent that most birders don’t know about: he’s a mimic, incorporating the sounds of other birds into his own song. But don’t expect to hear him caroling like an American Robin, or giving the rich warbling song of a Purple Finch. Instead, he selects halfsecond “clips” of bird sounds, compresses them into a rapidfire mashup of call and song fragments, and delivers them so quickly that it’s hard to perceive what he’s imitating. A single male can imitate dozens of species.
Certain bird sounds appeal to Lesser Goldfinches, such as the killy-killy-killy of the American Kestrel, the pee-er of the Western Wood-Pewee, the pit-a-tik of the Western Tanager, and the keeer of the Northern Flicker. A Lesser Goldfinch may also mimic the calls of his close relatives, the American Goldfinch and the Pine Siskin. Most of these are loud, simple calls that the Lesser Goldfinch hears in his open woodland habitat. The function of the Lesser Despite the Lesser Goldfinch being noticeably smaller, Goldfinch’s mimicry isn’t well understood, but a male with it’s often other field marks that help birders tell the two a large repertoire of song imitations is likely signaling his apart. Noting the wing bars, color of the undertail coverts superior fitness in some way. Neighborhood Naturalist, Spring 2017 v15 #1 • page 1