The Scottish Crossbill
This rare, large-billed red crossbill inhabits the remaining patches of pine woods in Scotland. Because other, slightly smaller, red crossbills (Loxia "curvirostra") also breed there without apparent hybridization, the Scottish crossbill has been recognized as the distinct species Loxia scotica. This is a situation similar to that in Scandinavia where large-billed parrot crossbills range in the same area as smaller "common" crossbills.
The behavior and natural history of the Scottish crossbill has been excellently and entertainingly documented in Desmond Nethersole-Thompson's 1978 book Pine Crossbills from T & AD Poyser. The book contains numerous photographs and illustrations, sonograms, interesting anecdotes, and hypotheses related to this form's evolution as outlined by Alan G. Knox.
