published Dec 17 2019 The Portsmouth Herald/seacoastmedia.com
I have been watching the “winter” birds return to my feeder – juncos and titmice, downy and hairy woodpeckers, cardinals and nuthatches. A birding friend who lives in Colorado just posted some gorgeous photos of red crossbills in his hometown of Estes Park. He said he is seeing them everywhere. I have never seen a crossbill (a type of large finch) even though we have both red and white-winged crossbills in New England, particularly in the winter. The North American range of the red crossbills that my friend Scott Rashid, founder of the Colorado Avian Research and Rehabilitation Institute, photographed extends down into the mountainous spruce and pine forests of Central America, while the white-winged crossbill range is mostly in the boreal coniferous forests of the north.
Both of these crossbills could, I think, be mistaken for a house or purple finch by a birder of my caliber (poor). I wonder whether I have seen crossbills in my backyard, but assumed they were house finches? Crossbills are larger than house and purple finches and both the white-winged and the red crossbill are rosy red all over with dark wings whereas the house and purple finches are reddish mostly in front. I’m describing male coloration – the females of all these species are drab, with the finch females being brownish and the crossbill females being yellowish-green.
Crossbills have a really wonderful adaptation to their lives in coniferous forests. Their bills cross at the tip so that when their bill is closed the tip of the bottom bill protrudes up and the tip of the top bill protrudes down forcing the upper and lower parts to cross each other. According to the Cornell Laboratory of Ornithology, crossbills employ a special technique using these unique bills to get to their favorite food, pine seeds. “A bird’s biting muscles are stronger than the muscles used to open the bill, so the Red Crossbill places the tips of its slightly open bill under a cone scale and bites down. The crossed tips of the bill push the scale up, exposing the seed inside.” They then extract the seed using their tongue and bill together.
One fascinating fact about red crossbills that Scott shared with me was the wide variety in overall size and particularly in bill size among what is now considered the one species of red crossbill (Loxia curvirostra). For example, there are types of red crossbills that are smaller in size with smaller bills who specialize in the smaller pine cones of hemlock trees while larger billed types will specialize in larger pine cones. There are currently 11 different types of red crossbill recognized in North America.
Another cool fact about both red and white-winged crossbills is that they are opportunistic breeders. Because their diet is largely composed of pine seeds (white-winged crossbills can eat up to 3,000 conifer seeds in one day!), because they feed pine seeds to their young, and because pine trees produce cones at different times of the year, these birds can breed whenever the seed crop is largest. This might mean nesting in the depths of winter – something I wouldn’t expect to see, a nest with young or some fledglings hanging out on a snowy afternoon.
The best time to find crossbills around is in the winter as they wander about in search of food. According to the Cornell Lab, “Crossbills are nomadic, especially in winter, and in some years irrupt far south of their normal range. At these times, they may show up in evergreen forests, planted evergreens, or at bird feeders.” Sometimes cone crops will fail in their breeding ground and migrants will show up further south in search of food. Making sure to include a variety of native conifers in your backyard can help attract them. Cemeteries and parks with ornamental spruce and pine plantings are also a good place to look as they often attract crossbills in winter.
Everyone I know who is a “real” birder has seen crossbills in New England in winter, so my personal challenge is to try to join the ranks. To that end I’ll be paying a little more attention to anything that looks like a house finch and to any reddish-pinkish birds hanging out in my conifers and feeding from the pine cones dangling from the upper branches.
Susan Pike, a researcher and an environmental sciences and biology teacher at St. Thomas Aquinas High School, welcomes your ideas for future column topics. She may be reached at firstname.lastname@example.org. Read more of her Nature News columns online.