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Cassia Crossbill - BirdForum Opus

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Alternative name: South Hills Crossbill

Loxia sinesciuris


Virtually identical to Red Crossbill; bill marginally stouter than the subspecies of that occurring in the same region (see Benkman et al. 2009[2] for details). Only reliably distinguished by sonogram analysis of its calls.


Restricted to the South Hills and Albion Mountains in Cassia County, south-central Idaho, USA.


This is a monotypic species[1].
It was formerly included in Red Crossbill.


Forests of Lodgepole Pine Pinus contorta subsp. latifolia.

Unlike elsewhere in the large range of Lodgepole Pine, the isolated South Hills and Albion Mountains have no American Red Squirrels Tamiasciurus hudsonicus; these are more efficient competitors for Lodgepole Pine seed resources, and prevent the establishment of Cassia Crossbills elsewhere[2]. The species' scientific name means "Crossbill without squirrels".



Primarily seeds of Lodgepole Pine.


  1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2017. The eBird/Clements checklist of birds of the world: v2017, with updates to August 2017. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
  2. Benkman et al. (2009). A new species of the Red Crossbill (Fringillidae: Loxia) from Idaho. Condor 111 (1): 169–17.

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