Laura Erickson's For the Birds

(Recording of a White-winged Crossbill)

Crossbills have been flying over the Lakewood Pumping Station already this fall. These exotic winter finches are distinguished by the pretty pink or orange-red color of the males, and, most of all, by the strange beak. The upper and lower mandible tips literally cross each other like a crooked pair of scissors. This unique and bizarre adaptation enables crossbills, better than any other group of bird, to exploit their primary food source–the seeds within pine and spruce cones. They shear apart the cone scales with the bill and then use their muscular tongue to extract the seeds. They can also use their bill like a parrot’s for climbing and hanging upside down. They often move from branch to branch with their beak as a balancing tool. And, also like parrots, they can hang upside down while feeding or when hiding from enemies.

Crossbills can breed as late in summer as August, or as early in winter as January—the timing depends strictly on the abundance of food, not the temperature. Most baby songbirds require large quantities of insects to survive and grow, which means most birds can only lay their eggs in spring or summer when insects are plentiful, but crossbill nestlings are among the very few species that are fed a diet of regurgitated seeds from the time they hatch, which means their parents can find food even in the dead of winter. Because of the fact that they do often have eggs or young to care for during cold weather, crossbills are unusually faithful brooders. Females have been known to sit on their eggs for over fourteen hours straight, and then to take a break for only a few minutes before returning to their responsibilities.

Crossbills are hatched with a normal, straight beak. At the time they leave the nest, the bill hasn’t yet crossed, but it soon does. Depending on whether the upper bill crosses to the left or the right, each individual spends its life eating with either its right or left side facing the tree.

For being as colorful as they are, crossbills aren’t noticed very often in the Northland. They seldom visit feeders except when there isn’t much natural food. In flight their simple “chip chip” call is the sort of thing normal people simply filter out of their consciousness. And when they feed high atop spruce and pine trees, they’re generally silent. They do drop pine cones and scales from the tops of trees, but only observant people notice that. It’s quite possible that Chicken Little wasn’t really hit on the head with either an apple or a piece of sky, but rather with a pine cone dropped by a crossbill.

This time of year, your best bet of spotting them is to listen for their chip chip call notes as small flocks fly over. They’re easier to spot in winter, when they drop their cone scales onto white snow, and when they spend a lot of time on roadsides eating salt.

Linneaus himself christened the Red Crossbill with its scientific name, Loxia curvirostra. Loxia comes from the Greek word loxos for crooked, and curvirostra comes from Latin for curved bill. In any language, the crossbill is a unique wonder in the world of birds.

(Recording of a White-winged Crossbill)

This is Laura Erickson, and this program has been “For the Birds..”