Skim A little Off the Top–The Black Skimmer
The bill of a bird often says a lot about how a bird feeds and what they feed on. If you’d never seen a Black Skimmer (Rynchops niger) before you could certainly tell they have a unique beak. The upper mandible is considerably shorter than the lower mandible. They don’t sift their food like a spoonbill. They don’t probe the mud and worm holes like an ibis. They don’t tear their food like a hawk.
Just as their name would suggest, they skim for their food. Flying low over the water, the skimmer places the lower mandible beneath the surface and continues to fly until it feels something touch the bill – and then snaps the bill shut. Amazingly, when the skimmer catches fish or other prey species, the head drops into the water and points to the tail end of the bird. The bird maintains flight, lifts the head back out of the water continues the hunt.
The lower bill of the Black Skimmer is constantly growing to combat wear from friction as the bird skims the surface of the water. The upper mandible does not grow at the same rate, resulting in an asymmetrical appearance. The difference in length of each mandible makes picking up objects with the bill more difficult. The upper and lower bills of juveniles are roughly the same until the bird matures.
The eyes of the skimmer are largely ignored by casual birders as they’re relatively small compared to the stout size of the rest of the bird. The eye has a pupil similar to that of a cat or an alligator and can be closed to a vertical slit. This type of eye is best for night foraging.
This flock of about 200-250 Black Skimmers was located on Bunch Beach in Fort Myers. The somewhat secluded sandbar is a preferred resting spot for skimmers, godwits, turnstones and other shorebirds. As I paused to take a photo, a jogger detoured towards the birds. Oddly, the skimmers took flight while other species remained. After a moment, the skimmers circled back and rested again on the sandbar.