If you’ve seen or heard unfamiliar birds recently, it’s probably not your imagination.
The mystery bird is about the size of a white-throated sparrow and is found primarily in groves of evergreens — spruce, hemlock and pine trees.
Males are red with dark wings; females are drab olive-gray. Both sexes have two bold white bars on each wing. The general impression also includes a big head, heavy bill and short tail.
If this description sounds familiar, you’re seeing white-winged crossbills.
Though members of the finch family, crossbills behave more like parrots. In fact, an alternate common name found in some references is the “spruce parrot-finch.”
Like parrots, crossbills are highly social and found in flocks year round. While foraging, crossbills maneuver awkwardly among evergreen cones. They maintain their balance by flapping their wings.
Their conspicuously crossed bill is uniquely adapted to remove conifer seeds lodged between the scales on evergreen cones. The upper bill is sharply decurved, which reinforces the parrot-like appearance.
For several weeks I’ve received many reports of white-winged crossbills from across Pennsylvania and a few from parts of Ohio and West Virginia.
Normally, these birds live in the boreal forest of Canada and the northern U.S.
Occasionally, when cone seeds are in short supply, crossbills “invade” southern states in search of food.
Pine siskins, common redpolls and red-breasted nuthatches are more familiar irruptive migrants.
When not feeding and when males sing, crossbills typically perch at the top of spruce trees.
The song is a series of trills and rattles that might be heard even now.
Crossbills are opportunistic nesters, and if food is abundant, they may actually nest in mid winter.
So if you live near a stand of conifers, particularly a spruce forest, you may get to see crossbills nesting.
Nests are placed on horizontal evergreen branches, often in loose colonies. The nest is an open cup of twigs, grass, and weed stems lined with finer plant fibers.
The female incubates two to four eggs for about 13 days. During incubation, the male feeds the female on the nest.
After the eggs hatch, the female broods the chicks, and the male feeds both his mate and the chicks.
A second species of crossbill, the red crossbill, is also being seen this winter, though not as commonly as white-wings.
Red crossbills are a bit larger than white-wings, have the distinctive crossed bill, but never have wing bars.
If you have not yet seen any crossbills, there’s still hope. Crossbills are nomads. If they exhaust the supply of confer seeds in an area, they move on.
White-winged crossbills, in particular, often exhibit three distinct seasonal movements.
The first movement comes in May, when cones begin to mature. At this time crossbills also eat buds, weed seeds, berries and insects.
In October and November, they move in search of ripening cones. If the cone crop is abundant, they may stay for months. But if they deplete the cone crop, they move on.
So in just a few weeks, if cone supplies become depleted, they will move again. That means there’s a good chance, if you haven’t yet seen any crossbills and if there are conifers nearby, they may arrive in three to four weeks.
Red crossbill identification can be confusing because there is tremendous variation within the species.
Eight different subspecies of red crossbills have been identified based on differences in bill size, voice and geographic distribution.
Some ornithologists argue as many as six distinct species comprise the red crossbill complex.
There’s no doubt this winter is one for the irruptive migrants. Northern seed crops have failed and many northern species are wandering south in search of more reliable food supplies.
Red-breasted nuthatches appeared back in September, and pine siskins, common redpolls and purple finches have arrived more recently.
But the star of this year’s irruption is the white-winged crossbill, a species that will be new on many birders’ life lists.