It’s on! We are having a superflight of northern finches into Maine this winter. Our Christmas Bird Counts have impressive totals of purple finches, evening grosbeaks. pine grosbeaks, pine siskins, red crossbills and white-winged crossbills.
We really aren’t too surprised to see this invasion. We know that the source of these invading birds into New England is the boreal forests of Quebec and Ontario. The production of cones by the conifers in those forests is meager this year. Since these northern finches depend on conifer seeds for much of their winter nutrition, irruptions into southerly areas to find cones is a necessity.
This year’s flight is even more spectacular when we take a broader view. Birders are finding common redpolls as far south as Alabama and Houston, evening grosbeaks as far south as the Gulf Coast states and white-winged crossbills, red crossbills broadly in the southeastern states and pine grosbeaks as far south as Washington, D.C. These finches rarely push so far south and almost never in the abundance of this winter.
I encourage you to log on to ebird.org to see the distribution of these finches in the United States. From the home page, click Explore, then click Species Maps and then type in the species whose current distribution you would like to see.
It boggles the mind to imagine how many northern finches we would have in Maine if the migrations stopped in New England rather than passing through. But all those finches to the south of us will migrate north in the late winter and spring so we will get a second chance to see them again along with the impressive numbers finches that will winter in Maine.
So why are we having such a superflight this winter? We can piece together a reasonable hypothesis from some observations of the Canadian boreal forest. Two of the past five years had bumper crops of cones. So, food supplies kept winter survival high and provided nutrition for nestlings during the nesting season.
We tend to think of finches as seed-eaters. However, finches will happily feed on insects when they are available. Spruce budworms have been abundant in the Canadian boreal forest for the past few years. Budworms are the caterpillars of several species of closely related moths. The caterpillars are serious pests of spruces.
Spruce budworms are readily gobbled up by northern finches and are fed to nestlings. This source of protein led to very high nesting success.
So, the past few years have been very good for northern finches and their populations have increased. All good things must come to an end and the poor conifer crop in Canada now leads to severe competition among the finches, forcing many individuals of many species to move into the United States.
This winter is a good time to make some valuable observations on red crossbills. We know that there are 10 red crossbill types in North America, based on their distinctive flight calls. With practice, it is possible to identify the type by ear. An even better way to identify the type of crossbill is to make a recording with your phone. Crossbill flight notes are loud and carry well, so you can get recordings of good quality with your phone,
The recording can then be uploaded to eBird, just like you would upload bird photographs. The Macaulay Library of Nature Sounds houses these recordings. Currently red crossbills take pride of place with the most recordings, about 10,000, of any bird.
You can learn more about red crossbill vocalizations at finchnetwork.org, a website devoted to finch research. You can find distribution maps and recordings of the different flight notes.
The project is headed by Matt Young who has boundless enthusiasm for finches. He provides his email on the site and encourages people to email him recordings of red crossbills. He will give you a firm identification of the call type.
Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at
whwilson@colby.edu
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