Guide to North American Birds

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Photo: Zak Pohlen

Formerly considered a localized form of Red Crossbill, the Cassia Crossbill was officially recognized as a full species in 2017. It lives only in lodgepole pine forests of the South Hills and Albion Mountains in Cassia County, southern Idaho. These two mountain ranges are unusual in having no red squirrels, which feed heavily on pine cones elsewhere. As a result, the lodgepole pines in these mountains have abundant cones, and the Cassia Crossbills are specially adapted to feed on the seeds from those cones. (The species name of this crossbill, sinesciurus, means “without squirrels.”) 
Conservation status Common in its limited range, with an estimated population of about 6,000, but vulnerable just because its total distribution is so small. The species could be wiped out by fires or other factors in the two mountain ranges where it lives.
Family Finches
Formerly considered a localized form of Red Crossbill, the Cassia Crossbill was officially recognized as a full species in 2017. It lives only in lodgepole pine forests of the South Hills and Albion Mountains in Cassia County, southern Idaho. These two mountain ranges are unusual in having no red squirrels, which feed heavily on pine cones elsewhere. As a result, the lodgepole pines in these mountains have abundant cones, and the Cassia Crossbills are specially adapted to feed on the seeds from those cones. (The species name of this crossbill, sinesciurus, means “without squirrels.”) 

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Feeding Behavior

Like other crossbills, usually forages in flocks. Clambers about over the cones of lodgepole pines, using its odd crossed bill tip to pry the cone scales apart to get at the seeds inside.



Diet

Feeds mainly on the seeds of lodgepole pine.


Nesting

Unlike other crossbills, which may nest at almost any season, Cassia Crossbills are consistent in their timing. They usually begin building their open cup-shaped nests in late March or early April, and the breeding season ends by late July.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

Most crossbills are nomadic and wander long distances, but the Cassia Crossbill stays in the same limited range year-round, making only minor local movements.

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Migration

Most crossbills are nomadic and wander long distances, but the Cassia Crossbill stays in the same limited range year-round, making only minor local movements.

Songs and Calls

Compared to the voices of other Red Crossbill types that occur in southern Idaho, flight calls of Cassia Crossbill are very low-pitched and hard, like chup-chup instead of kyip-kyip.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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