I see why they are called Red Crossbills

The emblematic character of the Red Crossbill

The emblematic character of the Red Crossbill

Of course, this title is presented with tongue firmly planted in cheek. They, or at least the males, are red, and the bills are crossed. These little finches (both Red and White-winged Crossbills) have evolved the only crossed bills of any North American bird. This arrangement of the mandibles is highly suited to prying open pine cone scales in order to remove the fatty, pine nuts within. The Maclay Flat area, near Missoula, MT, has been absolutely loaded with Red Crossbills this winter. They can seen flying in the typical bounding finch flight pattern between the treetops. They rarely seem to come down to our inferior level.

The most unique fact about the Red Crossbill is that the “species” may actually be comprised of up to 9 cryptic species. These “types” are divided by variances in the call notes and the morphology of the bill. These differences in bill size and shape seem to be related to the dominant type of conifer utilized as a food source. Types 2 through 5 and 7 have been found in Montana.

  • Type 2 – ponderosa pine
  • Type 3 – western hemlock
  • Type 4 – Douglas-fir
  • Type 5 – lodgepole pine
  • Type 7 – seems to be a generalist
The birds in these images seem to belong to the Type 2 group based on their call and habitat. The call resembles “kewp” in tone. The differences are rather subtle, and if, or probably more accurately when, the Red Crossbill is split along these Type lines, there will be many birders wandering around the forest in a bewildered state.

Pair of Red Crossbills exchange a glance

Pair of Red Crossbills exchange a glance

Female Red Crossbill being characteristically yellow

Female Red Crossbill being characteristically yellow

The crossed mandible tips are evident

The crossed mandible tips are evident

Notice the unique undertail covert pattern

Notice the unique undertail covert pattern

Written by Radd Icenoggle

I am a native Montanan, who has spent a lifetime as an outdoors and wildlife enthusiast. I earned a degree in biology with an emphasis on habitat relations. During my studies, I had the great fortune to research and compose a thesis that explored the effects of slope aspect on...
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