Red Crossbill

Red Crossbill

Loxia curvirostra. By Julie Lue

This story is featured in Montana Outdoors March-April 2018 issue

Red crossbills don’t visit my yard every year. But when they do, my family and I sometimes see dozens every day. They decorate the trees with their brick-red or olive plumage, while calling out with springtime chirps even in winter. Their presence reminds us to check the ponderosa pines near our house. We almost always find a big crop of cones, packed with seeds that provide one of the crossbills’ main food sources. If we’re lucky, the birds stay to nest and raise their young before they leave in search of another productive grove.

These sturdy-looking finches are about the same size as bluebirds, but with bulkier heads and necks. Males are rusty red or reddish gold with a dark brown tail and wings. Females are usually olive green to yellowish, also with a dark tail and wings. Juveniles have streaky brown-and-white coloring and look a bit like pine siskins. The young leave the nest with uncrossed bills. By the time they are about a month old, they develop the species’ distinctive feature: a large, curved bill with tips that cross. Of all the birds in the world, only the six crossbill species have this characteristic.

Red crossbills are cone specialists. Their specially adapted bills allow them to pry open the cones of pine, spruce, Douglas fir, and hemlock trees. To reach the seeds, a crossbill inserts its partially open bill into a cone and bites. The curved tips push up and down to open the tightly closed scales. Crossbills also consume other seeds and insects, as well as snow or water every day. A clean water source may attract them to your yard.

Red crossbills make a variety of calls, but their flight call—kip-kip or jip-jip—is probably the easiest to recognize. In North America, researchers have identified 10 different types of flight calls. Birds with different “call types” act somewhat like different subspecies or even species. They don’t interbreed, and their beak size and preferred food differ. Types with bigger bills tackle large cones like those of the ponderosa pine, while those with smaller bills specialize in the smaller cones produced by spruce or Douglas fir. In 2017, scientists split birds with one of these call types off from the red crossbill and recognized them as members of a unique species, the Cassia crossbill.

Though most birds nest in spring, red crossbills may start their families anytime from late winter to early fall, as long as they find enough cones. Parents can raise more than one brood each year, and sometimes young crossbills breed even before they have grown their adult plumage.

A female crossbill incubates her eggs for about two weeks in a well-camouflaged, bowl-shaped nest. After the eggs hatch, both parents feed the chicks a paste of regurgitated seeds and, a week or so later, whole seeds. Two to three weeks after that, the entire crossbill family abandons the nest, though adults still help provide food until the young become skilled at opening tough cones.

In the Bitterroot Valley, I once found crossbills nesting in early March. I spotted a female carrying dried grass to a clump of ponderosa needles near the end of a branch. Inside the clump, barely visible, was her softball-sized nest of grass, pine needles, and a single feather. Five weeks later, three young crossbills flew away.

Habitat and range
Red crossbills live in mature coniferous forests throughout much of North America and parts of Eurasia. In Montana, they show up sporadically any time of year in all but the northeastern corner, where you might see them during winter. These nomadic birds follow their food supply from grove to grove. Along the way, congregations of red crossbills may appear in “irruptions”: sudden migrations of large flocks to unexpected places.

Conservation Status
Red crossbills are both common and abundant in Montana. Because they depend heavily on older trees, which produce the most generous cone crops, populations may be vulnerable to the loss of mature forests. Bear bullet

Julie Lue is a writer in Florence.