The Cassia crossbill is a passerine bird in the family Fringillidae. It is endemic to the South Hills and Albion Mountains in southern Idaho. Cassia crossbill rarely interbreeds with other call types that move into the South Hills of Idaho yearly, and can be considered to represent a distinct species via ecological speciation. The Cassia crossbill have specialized beaks to access the seeds of the lodgepole pine cones in this region, but are poorly adapted to other pine cones in surrounding regions.
Region
Southern Idaho, Western United States
Typical Environment
Restricted to coniferous montane forests dominated by lodgepole pine in the South Hills and Albion Mountains. It forages primarily in mature stands with persistent, serotinous cone banks, often remaining in the same groves year-round. The species is poorly adapted to other conifers in surrounding ranges and seldom disperses beyond its core habitat. Within its small range it may shift locally with cone availability but remains strongly site-faithful.
Altitude Range
1600–2600 m
Climate Zone
Continental
Ease of Keeping
Beginner friendly: 1/5
This crossbill evolved in the absence of red squirrels, leading to unusually tough, serotinous lodgepole pine cones and a bill specialized to pry them open; its name sinesciuris means 'without squirrels'. It is confined to the South Hills and Albion Mountains of southern Idaho and rarely mixes with other crossbill call types. Climate change, altered fire regimes, and cone supply fluctuations pose significant threats to its tiny range.
South Hills - Idaho
Temperament
social and active
Flight Pattern
short rapid wingbeats with undulating flight
Social Behavior
Often forms small to medium flocks that move among cone-rich trees. Breeding can occur opportunistically whenever cone crops are abundant, with pairs nesting high in conifers. Nests are cup-shaped and built from twigs, bark, and plant fibers, and both parents help provision young.
Migratory Pattern
Resident
Song Description
Flight calls are hard, husky jip or chew notes that differ subtly from other crossbill types. The song is a jumbled, warbling series of trills and chatters delivered from treetops, sometimes interspersed with the characteristic flight calls.
