Vegetarianism isn’t popular among songbirds. Few caterpillars or other insects are safe when warblers, wrens or chickadees are about. Even birds that are primarily seed-eaters, such as sparrows, shift to a diet high in animal matter when chicks are in the nest. The rapidly growing youngsters need protein to prosper.

Enter the American goldfinch. The gorgeous little “wild canaries” go against the grain by eating almost nothing but grains and other vegetable matter. Goldfinches commonly visit backyard feeders and especially covet thistle seed. In wilder places, they also seek sunflower seeds, grasses and myriad other types of plant fruits. Although goldfinches occasionally wolf down an aphid or two, for the most part they shun the bugs.

When goldfinches descend on a ripe patch of sunflowers or well-stocked feeders, it’s as if a pack of debonair feathered piglets has landed. Many a collector of wild prairie seeds has been thwarted by the finches. Arrive to the flower patch too late and you’ll be greeted by little flecks of gold bouncing between the seed heads, stripping them of their fruit. Not to fret, though: The finches rightfully have first dibs.

Their vegetarian preferences serve goldfinches well when it comes to parasitic brown-headed cowbirds. Female cowbirds dump their eggs in other bird species’ nests, usually to the detriment of the host. The growth of the cowbird chick outstrips that of the native chicks, which often perish due to the cowbird receiving most of the parent’s food. Cowbirds don’t thrive on plants alone, however, and they soon die when subjected to the vegetarian diet of the goldfinch.

Male American goldfinches are now at the peak of their feathered finery. They sport a jaunty black cap and ebony wings and tail, which form a striking contrast against brilliant golden-yellow body feathers. Females don’t attain the bright colors of males, resembling a somber version of their showy mates. Goldfinches seem to exude happiness, gamboling about with an undulating flight constantly punctuated with sweet singsong twitters. They are social animals, too — quite tolerant of their brethren and prone to flocking at favored feeding sites.

Goldfinches are busily breeding now. They delay nesting to coincide with the maturation of thistles, coneflowers, coreopsis and other plants in the massive sunflower family. The down of ripe thistle, especially, is heavily integrated into their nests, and late summer’s abundant crop of seeds provides fodder aplenty for the chicks.

Enjoy the colorful male goldfinches while you can. Come fall, they will commence the most conspicuous molt of any of our songbirds, rapidly shedding their lemony feathers and taking on the muted tones of the females. They’ll ride out the winter dressed down. But come spring, the male goldfinches will cast off their low-key plumage and flash to life in a living sunburst explosion — Nature’s wild canaries reborn.

Naturalist Jim McCormac writes a column for The Dispatch on the first and third Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.