- ORDER: Passeriformes
- FAMILY: Fringillidae
The Cassia Crossbill, a finch with a crisscrossed bill, is closely related to the widespread Red Crossbill and was recognized as a full species in 2017. Unlike the nomadic Red Crossbill, the Cassia stays put year-round in a single county in Idaho, feeding on lodgepole pine cones that the Red Crossbill can't open. Groups of the red and yellow finches dangle from cones, quietly munching on seeds, until they erupt into flight with a kip. The species' small population and geographic isolation makes it vulnerable to extinction.More ID Info
Find This Bird
Cassia Crossbills occur only in Idaho's South Hills and Albion Mountains, so you'll have to head there to see one. Luckily, unlike other crossbills, they are year-round residents, which makes finding them a lot easier. They tend to be in older, more open patches of lodgepole pine where they can find older cones that are easier to open. Before you go, study up on their call because Cassia and Red Crossbills are best separated by voice, and even then it often requires analysis of a recording. Idaho Birds offers site-specific information on where to find Cassia Crossbills. eBird also has a primer on identifying crossbill call types.
- Piquituerto de Cassia (Spanish)
- Bec-croisé de l'Idaho (French)
- Cool Facts
- Prior to 2017 the Cassia Crossbill was considered 1 of 10 types of Red Crossbill, all distinguished by differences in their calls and slight differences in bill size. But researchers discovered that it doesn't breed with other crossbills, has a thicker bill, and isn't nomadic. Its name comes from Cassia County, Idaho, the only location where it occurs.
- Squirrels are a common sight in many forests, but not in the lodgepole pine forests of Idaho's South Hills and Albion Mountains. And it is their absence that favored the development of lodgepole pine cones that need fire and high temperatures to open. The crossbill, not to be deterred by the pine tree's protective measures, slowly evolved a thicker bill giving them access to the seeds. This tit-for-tat between the lodgepole pine and the crossbill is called an evolutionary arms race.
- Deer aren't the only animals that visit salt licks. Crossbills also need a bit of salt in their diet and seek out salt found in clay that hangs from the roots of upturned trees.