by Allan Worms, PhD., Wildlife Biologist (retired)
Snowy Plovers, a rare and beautiful little bird, listed in Florida as Threatened, have been joined on Siesta Key Beach by two additional imperiled species: Least Terns — the smallest of the American terns — and the dramatic Black Skimmer!
In previous editions of Siesta Sand we have introduced the Snowy Plover and right now our beach has these two more rare and exceptional birds breeding, laying eggs and raising chicks.
Dainty, but determined to survive, the Snowy Plovers are the color of Siesta Key beach sand. Even adult birds are hard to see until they scurry out from under beach walkers’ feet. The newly hatched chicks, however, are dramatic! Only a little larger than your thumb, these precocious little hatchling birds visually suggest a sand colored cotton ball running about on toothpick legs. They are insectivores and forage along the beachfront looking for insects and other small invertebrates.
Least Terns are beautiful small terns which have a crisp white triangle on
their front brow when in breeding plumage (think of a “V”). And with their yellow bill and rapid dives for small fish they are quite distinctive. Like the snowy plovers, small terns are also highly vulnerable to disturbance by humans, dogs or other pets. They are listed as threatened by the Wildlife Commission.
Interestingly, Least Terns and Snowy Plovers get along really well when nesting near each other. Possibly the fact that snowy plovers feed on insects and invertebrates in the sand and that least terns dive for small fish and are thus – non-competitive — is an asset in their cooperative behavior.
Another feature of least terns is that they are VERY protective of their nests. Don’t get too close — you’ll get “dive-bombed”!
And note the Black Skimmer. This medium sized black bird exhibit’s a brilliantly colored and unique adapted bill that sets it apart from all other American birds. The large reddish-orange and black bill is almost knife-like in appearance. In hunting for food the bird actually skims the water with its long, very narrow lower mandible slashing through the water seeking small fish and other edible objects. When it feels a small fish, shrimp or crustacean the upper and lower bills shut tightly allowing the bird to swallow its prey.
An additional feature of the Black Skimmer is that while it can see and hunt in the daytime, mostly it is crepuscular and nocturnal. This means it hunts most often in the evening, through the night and in the early morning. And a final unique feature of the Black Skimmer is that its pupils are narrow in full light, but able to open to a full round aperture when they skim the water at night!
Each of these birds is rare and subject to having their nests ruined by humans, dogs, crows and other attacks. This spring one Snowy Plover hen even lost two eggs from her nest to a ghost crab. Fortunately she was able to incubate the third egg and it is now a healthy chick running around looking for insect foods.
Wherever you walk on Siesta Key Beach, be aware of these rare birds. Stay out of the posted areas where they nest, but by all means watch the birds, talk with the volunteer bird stewards and enjoy these birds’ beauty. Allan J. Worms, Ph.D. Wildlife Biologist (retired) Photos by Claire Herzog