There are 3 recognised species of Crossbill in the Scottish Highlands, with many additional intermediate forms. All are inseparable on plumage characteristics and can only be identified by their bill measurements and calls. On sight views alone, few individuals can be identified to species with any degree of certainty due to the high degree in variation in bill size within each species.
The above female has a bill with a quite deep base, a reasonably strong curve to the upper mandible and a slight bulge to the lower mandible. These are all features indicative of Scottish Crossbill (Loxia scotica). However, it was paired with the male in the top photo which has a bill far more typical of Common Crossbill (Loxia curvirostra) so this could either be an example of a hybrid pairing, a large-billed female Common Crossbill or a very small-billed Scottish Crossbill.
Ray Wilson owns the copyright of all images on this site.
They may not be used or copied in any form without prior written permission.
raywilsonphotography@googlemail.com