By Anna Morris
Lead Environmental Educator
For many of us at VINS, this winter has been remarkable. In addition to the cold, snow, and ice, the Center for Wild Bird Rehabilitation has seen record-breaking numbers of patients. But one of the most interesting things about those patients was who they turned out to be.
Last winter the northeast experienced an irruption—a term biologists use to describe a sudden change in the population density of an animal—of Snowy Owls. Large numbers of these normally arctic tundra-dwelling raptors found themselves moving south through the United States, looking for open territories and good hunting grounds for small rodents and birds. This winter we are once again experiencing an irruption, but this time of boreal songbirds.
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| Adult Male, wikimedia commons |
Boreal songbirds are birds that breed in, migrate through, or otherwise rely on North America’s boreal forest habitat, according to the Boreal Songbird Initiative. This unique habitat, consisting of mostly spruce, pine, and larch trees, covers 1.5 billion acres of land in Canada and Alaska. The boreal forest not only provides a safe haven for more than 300 bird species and large mammals like caribou and wolves, but the trees sequester large amounts of carbon dioxide from the atmosphere, slowing the effects of climate change.
Evening Grosbeaks, Bohemian Waxwings, Common Redpolls, and Pine Grosbeaks are among the boreal songbird species that bird-watchers all over Vermont have been seeing in unusually high numbers this winter. Professional “finch forecaster” Ron Pittaway of the Ontario Field Ornithologists documents the abundance of boreal bird food crops like conifer seeds and berry-bushes each winter, and predicted that these four species would be abundantly seen due to the low amount of their normal food resources in the summer of 2018.
He appears to have been exactly right. At the VINS Center for Wild Bird Rehabilitation, we have seen 7 Pine Grosbeaks as patients since the beginning of December 2018. (In 2017 and 2016, we saw none at all). Pine Grosbeaks are large, frugivorous (“fruit-eating”) finches, a food source which is highly variable year-to-year, and so occasionally drives them to seek out more resources further south than their normal range. Their 10 inch length and 2-3 ounce bulk may not seem “large”, but you might spot Pine Grosbeaks foraging in large flocks in the winter for nuts and seeds as well. Their scientific name, Pinicola enucleator, means “pine tree dweller, who removes the kernel”, as from seeds.
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| Adult Female, wikimedia commons |
Of our 7 Pine Grosbeak patients this winter, nearly all came in with head trauma, which was likely sustained from colliding with windows. These northern birds have little experience with human settlements, and clear glass confuses them, causing injury. There are many ways to minimize window collisions by birds, and save lives. Putting up ultraviolet reflective stickers or protective screens will help birds recognize an unsafe place to fly.
Our patients in December came from towns farther north in Vermont, and those recent comers have been from right at our latitude, so it has been interesting to track the southward movements of this species in our own state. Three of our Pine Grosbeak patients were able to be released back into the wild, and one young male has joined our resident songbirds on exhibit at the VINS Nature Center.
Stop by VINS soon and meet our newest songbird educator, Hanover. Hanover the Pine Grosbeak came into our care on January 17th, 2019 with a fracture to his left radius/ulna (forearm bones) near the wrist. Though he was in a body wrap for a week to try to heal the fracture properly, it was deemed too severe for release as he is unable to get enough lift for flight even after 3 weeks of healing—bird bones heal a lot faster than humans, and so by this point we know that Hanover’s injury is permanent. He sits near the top of the enclosure, and we’re sure he’s eager meet his new fans!