Our wintertime warblers will migrate north shortly

Yellow-rumped Warbler

All winter long, you may have seen the flash of a yellow songbird pecking for seed at your bird feeder. No, it wasn't a male goldfinch. 

The American Goldfinch's bright yellow color is seen only in warmer months. As winter arrives, the male takes on a dull, olive plumage similar to that of the female, which wears that color all year long. Also, you might notice a black wing bar amid the olive. That's sure sign that the bird you've seen is a male goldfinch. The male will soon return to its vivid yellow; the striking display is meant to attract a mate.

The yellow flash that is seen locally in the winter is a Yellow-rumped Warbler, the only species of warbler that makes its home here in the winter. Soon the Yellow-rumped Warbler will depart, heading north to breed. Taking its place among warblers will many different species, each with their coloration and their own melodious warbling song.

The trill of a Yellow-rumped Warbler is a song of four to seven syllables (tyew-tyew-tyew-tyew-tyew-tyew-tyew) and an occasional call note (check or chip).

Yellow-rumped Warblers are one of the few warblers that come to feeders to eat. They consume sunflower seeds, suet, peanut butter and raisins. 

In nature, they eat waxy fruits—bayberries and was myrtles in particular—that most other songbirds usually ignore. The trick is the warbler's digestive system, which is able to to transform the waxy fruits into essential nutrients. They'll also eat juniper berries and the fruits of poison ivy, Virginia creeper and dogwood.

Their digestive abilities is one reason they winter so much farther north than other warbler species.

You'll see them foraging in shrubs or trees, often in parks, along woodland streams and in open pine and mixed pine-oak forests. They'll even visit cow pastures where they pick goodies from piles of manure. If you happen to be at the seashore, you may see them there, in the dunes. The easiest time to see them is during migration.

In the depths of winter, the birds are mostly a streaky brown and yellow, with the brightest yellow appearing on the top of the rump, and to a lesser extent on the throat and beneath the wings. Right now, the birds are beginning to transform into a brighter color: a dazzling yellow and gray. The males display flashes of white on their wings. The females are more subdued and a bit more brownish.

The birds will be their most numerous in mid-April, as their comrades who wintered a bit farther south begin to enter the Lehigh Valley. By mid-May they are gone, having headed north in flocks to Canada, Alaska or the Rocky Mountains to breed. They'll being returning in large numbers in late September, according to Birds of the Lehigh Valley and Vicinity.

Yellow-rumped Warblers lay four or five eggs in nests 50 feet above the ground, usually in a horizontal branch away from the trunk. The female has two broods.

During breeding season, the warblers change their diet a bit. They primarily eat insects, which they catch in midair. They also forage in leaf litter for spiders and caterpillars, in addition to insects find there. Early ripening berries remain a treat.

Fortunately the species is abundant and widespread, according to the National Audubon Society.

So be on the lookout. You may find a Yellow-rumped Warbler nearby, if not around your feeder than perhaps along the tree line at your favorite park or stream.