When food supplies go down and demand goes up, birds we don't usually see, can end up at our backyard feeders.
When feed is scarce Bohemian Waxwings like this one come south. (Courtesy Doug Lloyd)
We interrupt our usual programming to report an invasion in our state! Don’t worry, I’m talking about a bird invasion. There are oodles of unusual species in New Hampshire this winter.
This is pretty exciting stuff for bird lovers. There are several species of songbirds that usually live well north of here in the boreal forests of Canada and don’t often venture this far south. But every few years, certain beautiful species such as redpolls, pine grosbeaks, and Bohemian waxwings make a local appearance. Sometimes these invasions can be quite dramatic, and huge numbers of unusual birds suddenly appear in our backyards!
So why would we see flocks of these northern birds one year and not the next? When a large number of birds of one species moves into a region where they do not normally occur, it’s called an irruptive migration. Biologists believe that these invasions occur when there is poor seed production in the north, forcing the birds south in search of food. Sometimes a lean year follows a year when food was unusually plentiful and more young birds survived, increasing the overall population. If seeds are scarce the following year, there are more birds competing for less food. So they head south and appear in our backyards, which is a real treat. For example, one winter a flock of more than five hundred Bohemian waxwings was spotted gorging themselves on crabapples. Now that’s an impressive sight and one you’d usually have to go to Canada to see!
So watch for these spectacular, fascinating invaders stuffing themselves with fruit and at backyard feeders, because we never quite know when we’ll see them again! Enjoy the show!
