Several members of the Finch family of birds periodically fly south of their range into southern Canada and the northern U.S. during the winter in search of food. Pine Siskins, Common and Hoary Redpolls, American Goldfinches, Red and White-winged Crossbills, Purple Finches and both Evening and Pine Grosbeaks participate in these irruptions. Whether or not these species extend their range further south in any given year has much to do with their diet and its abundance or lack thereof on their wintering grounds . According to Ron Pittaway’s 2016-2017Finch Forecast (http://ebird.org/content/canada/news/ron-pittaways-winter-finch-forecast-2016-2017/ ), many of these birds will have a difficult time finding natural food sources this winter in Southern Ontario and the Northeast due to poor cone crops. Some may head north or west, where crops are much better.
Even if there were plenty of cones in the Northeast this year and many Canadian seed-eating finches were headed south of their normal range, we might not see large numbers of Pine Grosbeaks. This is due to the fact that the Pine Grosbeak’s diet is not limited to seeds, but includes buds, insects and fruit. Most of these birds are staying north this winter because of an excellent crop of Mountain-ash berries across the boreal forest. They eat these and other fruits by biting through and discarding the pulp and crushing the seed (which gives them a slightly unkempt look). We will see some — there have been several sightings of mostly small flocks of Pine Grosbeaks in New England in the past few weeks, lingering just long enough to consume what European Mountain-ash berries and crabapples they can find. But those of us who see them are very fortunate this year. (Photo: female Pine Grosbeak eating crabapples.)
Thank you to all of you who so kindly wished me well. I’m sure those wishes are what hav me bright-eyed and bushy-tailed once again!
White-winged Crossbills inhabit the boreal forests of northern New England, the southern edge of their breeding grounds. This species, as well as Red Crossbills, are named for their bill which is supremely adapted to extracting seeds from conifer cones. Crossbills use their crossed bills to wedge open cone scales, after which they lift the seeds free with their tongues. Individuals can eat up to 3,000 conifer seeds per day.
White-winged Crossbills are erratic nesters that have been found breeding every month of the year. The birds nest whenever the available food supply is sufficient for egg formation and is likely to remain sufficient for at least three weeks, during the more energy demanding nestling stage.
Three nesting periods have been observed, each corresponding to the ripening of cones from different conifer species. The first season occurs in early July, when the cones of Tamarack, or American Larch, and White Spruce mature. The second nesting period begins in January and February, when they rely mainly on White and Red Spruce cone crops and the third season is starting now, as Black Spruce cones begin to open up. (Photo: public domain, male White-winged Crossbill)
The birds most commonly associated with winter irruptions are the winter finches — Pine Grosbeak, Red Crossbill, White-winged Crossbill, Purple Finch, Pine Siskin, Common Redpoll, and Evening Grosbeak. Their food supply, or lack thereof, in the Canadian boreal forests where they normally overwinter, determines whether or not they will be seen as far south as the U. S. Key trees affecting finch movements in the boreal forest are spruces, birches and mountain-ashes.
Common Redpolls feed primarily on the catkins (seed-containing fruit) produced by birch and alder trees. When catkin production is low further north, as it is this winter, Common Redpolls leave these areas and irrupt into areas where food is more plentiful. (Photo: male Common Redpoll)