I recently checked the bill length to bill depth ratios of Cackling and Canada Geese, expecting to find a consistent and useful difference. The bills of Cackling Geese are often described as “stubby” and I was always under the impression that they were short and relatively deep. Working with the measurements in Pyle (2008, Identification […]
Archives for September 2010
In discussing the identification of the woodpecker in the Luneau video, my colleagues and I suggested that the extensive white visible in the wings could be accounted for, in part, by the natural twisting of the wings during flight. A bird flying away would show the underside of the wings during the entire downstroke. In the […]
In my last post I mentioned that the juvenal plumage of type 4 and type 2 Red Crossbills seemed to be consistently different, and here are two photos that illustrate the differences.
Last month (late Aug 2010) I had the pleasure of spending some time at the Nature Conservancy’s Pine Butte Guest Ranch in Montana, where an irruption of Red Crossbills was in full swing. Each day around the ranch I saw and heard hundreds of crossbills, of two main call types, and these offered a great […]
Up until the 1980s, permanent sea ice north of Canada and Russia would have been a substantial barrier to the movement of birds around the Arctic Ocean, inhibiting passage east or west along the northern shores of North America and Siberia. As can be seen in the two images above, however, those barriers have almost […]