Black Skimmers (Rynchops niger) are not perturbed by a cloudy, rainy day in Brazoria National Wildlife Refuge. They were actively feeding during the dreary conditions this day. I have thought about and observed the peculiar feeding habits of the Black Skimmer many times. However had never been able to capture good images until now. My close presence to the feeding area did not disturb the Skimmers. I used my vehicle as a blind near the edge of the marsh.
Black Skimmers are found around bays, beaches, shell banks, spoil islands, and coastal marshes. They nest mostly on sand, and dredge spoil and often have large nesting colonies near the nests of terns. Skimmers visit all coastal waters of the continental United States and Mexico, with the exception of the Pacific Northwest and Northern and Central California.
Black Skimmers have a light graceful flight, with steady beats of their long wings. They feed, flying low over the water surface with the lower mandible skimming the water for small fish, insects, crustaceans and molluscs. They catch prey by touch during the day and especially at night. Additionally the bird uses a two pass strategy. The first pass attracts fish and the during second pass over the same track, the lower mandible snaps shut when encountering the prey.
The Skimmers have eyes with dark brown irises and vertical pupils. Likewise nocturnal and aquatic vertebrates have this characteristic. It does however, allow for a greater reduction of the pupil in nocturnal animals that must protect the iris in bright sunlight. These eyes are very unique for a bird and are not an adaptation for improved vision in dim light. This is consistent with the night feeding behavior of Black Skimmers. The relatively small eye of the skimmer compared to other birds does not hamper the the tactile feeding method. Black Skimmers rarely use their eyes to locate individual prey. – Check out the extended lower mandible.
