A bird irruption is an irregular migration of a large number of birds to areas where they aren’t typically found, usually motivated by the search for food.
In Michigan we can expect a few new faces at the bird feeder this winter. I know this because every year ornithologist Ron Pittaway analyzes the cone and berry crops of Spruce, White Pine, Hemlock, White Birch, and Mountain Ash trees in Canada. He also looks a tamarack (American larch), balsam fir, white cedar, yellow birch and alders which are not the main seed sources but help create an overall picture of the food available to birds in the winter. Then he predicts if certain birds will irrupt into the northern U.S. or remain further north. This year Ron Pittaway's Winter Finch Forecast predicts several birds may irrupt into Michigan.
The potential for irruptive birds that you may see at the birdfeeders include:
Purple Finch- Similar in looks to our common House Finch, a few Purple Finches may frequent finch and sunflower feeders this fall..
Image by jackanapes via FlickrCommon Redpoll-A poor white birch crop across much of northern Canada and a good redpoll breeding season in 2010 with double and possibly triple broods reported means we may see redpolls at the finch feeders this winter.
Image via WikipediaRed-breasted Nuthatch- The poor cone crops on spruces, balsam fir and white pine in the mixed coniferous/deciduous forest region across Canada means there will probably be an increased number of nuthatches at the suet, nut, and sunlower seed feeders.