A strange and mysterious creature is popping up across Maine with increasing frequency this year. It is a bird, a bit larger than a house finch or purple finch but smaller than a robin. The males have a muted red head and body, and dark brown wings and tail; the females and males in their first year have a glowing golden head and body, and dark wings.
None of these features are particularly unusual.
What makes this bird so fascinating is its oddly crossed bill. How odd? The tips of the upper and lower parts of the bill grow past each other and cross. It looks so bizarre that someone who didn’t know that this is normal for this species would likely assume that the bird was suffering from disease or injury. But for these birds, the crossed bill is a special feature of their anatomy that allows them to easily extract food that is hard for other birds to access. They eat the seeds of trees like pine, hemlock, firs, and spruces, and the find their delicacy nestled down in the crevices of hard-to-access cones.
What is this mysterious creature? It is the red crossbill.
Currently, worldwide there are considered to be six formally described species of crossbill, with three officially recognized species here in North America. Right here in Maine we have two of those species, the red crossbill and the slightly smaller white-winged crossbill. The latter species is generally the more common of the crossbill species in Maine, but like many finches (crossbills are part of the larger family of finches), white-winged crossbills have boom and bust years depending on the crop of spruce and fir cones available in any given year.
Red crossbills are more mysterious in many ways. Research over the last 30 years has shown that there are at least 10 different types of red crossbill across North America (and in high elevations of Central America) and that there are more across Europe and Asia. The North American types can be distinguished by experts analyzing sound recordings of their calls. One of our old friends from the Cornell Lab of Ornithology, Matt Young, is one of the experts who will identify the types of red crossbill based on sound recordings submitted to him via eBird.
The breeding range of red crossbill is generally south of the range of white-winged crossbill but with broad overlap, and even the delineation of the breeding range has been confusing. That’s partly because red crossbills are quite adaptable to feeding on the seeds of different species of pines, firs, and spruce, perhaps because of their generally larger bill compared to the white-winged crossbill. That adaptability seems to have allowed them to do well in pockets of coniferous forest habitat across a wide region. But their ability to move around and breed in a spot where they find abundant food one year and abandon it the next, means that our human notions of relatively permanent breeding ranges just doesn’t fit very well.
Here in Maine there have been in the past, long strings of years with relatively few sightings of red crossbill across much of the state. In contrast, the last two years, and certainly this year in particular, red crossbills are being found in many areas. We have had red crossbills flying over in the Gardiner and Richmond areas several times just in the last few weeks, and many other birders have been reporting them to eBird as well. The numbers on Mount Desert Island this summer appear particularly high based on eBird reports but red crossbills are being seen across much of the state.
Red crossbills often breed in August and September as they take advantage of pine, hemlock, fir, and spruce cones where seeds are available during that time. Keep your eyes and ears (they have a characteristic “jip, jip, jip” call in flight) open in the coming weeks to see if you can get a glimpse of the strange and mysterious red crossbill.
Jeffrey V. Wells, Ph.D., is a Fellow of the Cornell Lab of Ornithology and Vice President of Boreal Conservation for National Audubon. Dr. Wells is one of the nation's leading bird experts and conservation biologists and author of “Birder’s Conservation Handbook”. His grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, formerly of the Cornell Lab of Ornithology, is a senior director at the Natural Resources Council of Maine, a nonprofit membership organization working statewide to protect the nature of Maine. Both are widely published natural history writers and are the authors of the book, “Maine’s Favorite Birds” and “Birds of Aruba, Bonaire, and Curaçao: A Site and Field Guide” from Cornell Press.