Wintering Robins

     Many people in the Middle Atlantic States regard American robins as a harbinger of spring.  Indeed, we do see flocks of them early in March running across lawns where they hadn't been all winter.  Those robins are north-bound migrants.  But other robins inhabit maturing suburbs and hedgerows in this area all winter, feeding on berries of various kinds and sheltering at night in coniferous trees and thickets of shrubbery.  They are not signs of the vernal season, but many people are glad to see them just the same.
     Though not announcements of spring, robins wintering in this area are still thrilling to see.  They are handsome in their brownish-orange underparts and gray-brown upperparts perched among the attractive berries they consume and roosting in other trees and bushes between feeding forays.  Groups of wintering robins flutter into trees and bushes loaded with colorful berries, feed on several at a time, then zip out to a nearby perch to rest and digest.  Many seeds the robins ingest are passed intact while those birds are on roost, spreading the range of the plants from which they ate berries and digested their pulp.  Robins help insure food supplies for themselves into the future.
     Flocks of robins make several trips to the berries every day until the berries are gone.  Then they move on to another berry patch and another, eating the berries and spreading their seeds. 
     Some of the plants from which robins get berries and berry-like fruits in winter are hawthorns, barberries, pyracantha, multiflora rose, winterberry bushes, American hollies and hackberry trees. Many of those berries are red or orange, which makes them more visible to berry-eating birds.  Robins also eat the colorful fruits of crab apple trees, the berries of poison ivy vines, and the pale-blue, berry-like cones of red junipers, a kind of coniferous tree. 
     Robins have competition for berries in winter.  Some of their more formidable rivals are starlings, cedar waxwings and northern mockingbirds.  Starlings and waxwings also travel in gangs and clean out berries from a tree or bush in a hurry.  Mockingbirds work individually through winter, but they are pugnacious in defending a patch of berries they will consume themselves through winter.  Mockers literally chase other birds away from "their" berries, which to them is a do or die activity.
     Watch for the attractive American robins around sources of berries the rest of this winter.  But if flocks of robins are spotted on lawns early in March where they hadn't been all winter, chances are they are migrants, and harbingers of spring.