Look for crossbills traveling in flocks of mixed males and females. The males are red, while the females are yellow. Photo by Ryan Mandelbaum FCC
Migrating from cone to cone, feeding on an ancient invention of almost 400 million years, the red crossbill finds seeds. Or perhaps more appropriately, the red crossbills find seeds, for they are almost always found in flocks, and almost always found near conifers. Using their crossed bill to pry open pine cones, crossbills feast. More than most birds rely on a single food source, red crossbills maintain near exclusive domain on the Pinophyta—consisting of eight families and 629 species worldwide—the conifers, or pines. There are, of course, birds with more exclusive specialties; namely island endemic birds whose preference spans a single species like the ʻŌʻū in Hawaii, which is now presumed extinct, but fed on the fruits of ‘ie ‘ie, a vine native to the Pacific Islands. The ʻŌʻū’ ‘s resemblance to the crossbill, with a similarly stout and crosswise beak, is no coincidence. The ancestor of Hawaiian honeycreepers is believed to be an ancient finch, same as the red crossbill.
A red crossbill—displaying it’s namesake “crossed bill”—perches at the tip of a pine. Photo by Ryan Mandelbaum FCC
But our red crossbills in Wisconsin pay no mind to their distant Hawaiian relatives—pine cones are on their mind and menu. More frequent in winter, red crossbills can sometimes be found among conifer plantations in southern Wisconsin, though the native evergreen forests and groves of northern and central Wisconsin provide a natural and widespread source of food. With the tendency of humans to move plants around, often catastrophically, we must have absolutely puzzled the crossbills. In southeastern Wisconsin, tamarack is one of the few native cone-bearing trees, but plantings of red pine, white pine, Colorado blue spruce, and Norway spruce to name a few have provided a surprising bounty of cones for crossbills to pick over. In fact, breeding of this species mostly occurs in northern Wisconsin, but due to conifer plantings in southern Wisconsin red crossbills breed as far south as the Kettle Moraine.
As many as eleven “types” of red crossbills can be found across North America, and these types could eventually be classified as different species. Each type has distinctive call notes, and the types are segregated based on beak size which corresponds with the birds’ preferred tree species based on their beak attributes. For instance, type 5 is also known as the lodgepole pine crossbill, and often feeds on lodgepole pine and can be found in the intermountain west but can also irrupt south to Mexico or west to the coastal ranges of California.
Red crossbills are frenzied feeders—look for them as they hang upside down from branches, maneuvering every which way to get at those cones. Photo by Andy Reago and Chrissy McClarren FCC
All of this crossbill insanity gets even more interesting, as some research suggests that crossbills have co-evolved alongside lodgepole pines on isolated ranges in the Rocky Mountains. The most common predator of lodgepole pine seed is the red squirrel. However, on ranges where the red squirrel is absent, red crossbills are much more abundant than would be expected, likely due to this unfettered food source. Presumably in response to the crossbill predation, the distal scales of the cones on lodgepole pine have thickened. And presumably in response to these thickening scales, crossbills have been measured to have thicker bills.
You might be able to find a group of red crossbills at Faville Grove this winter, in any area with conifers. Their red body (no white wing bars) and a crossed beak are a striking and delightful find for the coming winter.
Written by Drew Harry, Faville Grove Sanctuary land steward
