If you ever spot a chimney swift perched on an electrical or telephone line, stop whatever you are doing and take a picture of it.  Your photo would be rare indeed.  This is because ornithologists believe these small birds are incapable of perching in such locations.

       This might seem odd since we routinely see mockingbirds, mourning doves, sparrows, red-shouldered hawks, sparrows, and many other birds perched on the wire.  The reason they are able to perch in such places is the structure of their feet and legs are very different from those of the chimney swift. 

       Instead, the chimney swift’s toes, nails, and legs are suited to cling to vertical surfaces such as upright trunks of trees, walls and the interior surfaces of chimneys.