Tuesday, March 18, 2014

Black Skimmer

On the Rockport, Texas, beach, behind the American Avocets in the photo above rests a large flock of Black Skimmers. A closer look at the skimmers, with their elongated lower mandibles, can be had in the middle photograph. To my surprise, I find I have not blogged about this species. The lower photo is a closeup of the bill, taken in Key West, Florida, in 2011.
Skimmers fly low, with their beaks open, dragging their lower mandible in the water. When they hit a prey item, the upper mandible snaps shut. Often skimmers will make a second pass over the ripple caused by the the mandible on the water. The thought is that small fish may be attracted by this ripple, and are then eaten by the returning skimmer. Even at night, without the aid of sight, skimmers are able to catch their prey by just feeling their strike.
Three species of skimmers are found around the world. Historically, skimmers belonged to their own family of birds, Rynchopidae. Now they are considered to be in a subfamily of gulls and terns. Ornithologists argue, however, if skimmers are more closely related to gulls or terns. Perhaps they are a sister-group to both gulls and terns, derived from some ancestor of all three groups of birds (Gochfeld and Burger 1994).

No comments:

Post a Comment