This morning while out photographing birds at a local wildlife refuge I came across this Red-winged Blackbird with a strongly crossed bill, which of course is not typical of the species. I’ve seen a few mildly crossed bills in this and other species in the past but never one quite this pronounced in a species where it isn’t “normal”.
Red-winged Blackbird with a crossed bill, perched on curley dock
There are species of birds in North America that have crossed bills as a species trait – the Red Crossbill and the White-winged Crossbill. Their crossed bills are an adaptation for extracting seeds from cones. Seeing this RWBB with a crossed bill naturally got me thinking about evolution. Variations occur throughout nature since each individual inherits a different combination of genes from its parents. This particular variation would likely be selected against in RWBB’s and would not persist since they do not typically pry seeds from cones. However, one can see how this same variation in the ancestors of todays crossbills would be the genetic fuel for the crossed bill trait they all exhibit today.
Ron
Jack, I’ve seen (and photographed) multiple bill deformities in a variety of species though not all of them actually involve crossing of the bills (the link you provide seems slightly ambiguous as to whether or not actual crossing of the bill is required for it to be the “disease” you mention). Some that come to mind are Red-tailed Hawks and Western Meadowlarks but there have been others. I’ll be emailing you.
Hi Ron – There is a disease in wild birds that appears to be spreading that may cause this (http://www.usgs.gov/newsroom/article.asp?ID=2633&from=rss_home). I am curious about incidences of crossed bills in the lower 48 states and wondered how often you have seen crossed bills and in what species (from your comments, it sounds like you have seen this before.) Thanks for posting – this is a beautiful photo!
Fantastic images; great patience on your part to be able to tell the entire story regarding the shrike. Also great to hear from you, I was thinking about you the other day but thought you might be in Montana or elsewhere. Thanks for sharing your work it is wonderful! Kepp up the good work.
Kim
Very interesting bird and bill. Good work documenting this abnormality.
Excellent image Ron and commentary on the crossed bill of this bird. It was an unusual find.