Skimming the Surface: The black skimmer cuts a striking figure in coastal FloridaJan 24, 2021 11:56AM ● By William R. Cox
The black skimmer (Rynchops niger) is a graceful inhabitant of the coast of Florida, notable for the way it forages by cutting through the surface of water with its lower mandible and catching small fish, shrimp, and other aquatic invertebrates. In Rachel Carson’s first book, Under the Sea-Wind, the skimmer is called a flood gull because of the way it feeds on a rising tide. This can be observed year-round on both the Atlantic and Gulf coasts of Florida. The black skimmer is also called sea-dog, razor bill, scissorbill, and shearwater.
The skimmer is a tactile hunter. When prey touches its lower mandible, the skimmer lowers its head and quickly snaps up the prey. It never dives for prey and rarely locates prey by sight. It feeds both during the day and night but mostly at night. The skimmer is different from other birds in that its lower mandible is much longer than the upper mandible. Its bill is so laterally compressed that it is difficult to see when observing it flying head on. It is also the only bird to close its pupil into a vertical slit.
This large black and white seabird has black upperparts with white underparts. Its bill is bright red with a black tip, and its legs and feet are orange to red. In breeding it is entirely black from the crown onto the back. A nonbreeding skimmer sports a white collar and dull black upperparts. The juvenile bird has mottled brown upperparts and a noticeably shorter bill. The lower mandible does not reach full length until adulthood. The male skimmer is larger than the female, and its bill is 10-15 percent longer. It is 17-18 inches long with a wingspan of 45-49 inches. While flying its wings appear exceptionally long for its body. It has a long bill, short legs, and short forked tail.
A permanent resident of Florida, the black skimmer inhabits natural sandbars, small coastal islands, shell banks, dredge-material islands, coastal beaches with little vegetation, and salt marshes. It has also been observed roosting on inland lakes such as Lake Okeechobee. The black skimmer is a threatened species in Florida, designated a Species of Special Concern by the Florida Fish and Wildlife Conservation Commission. This is because of habitat loss resulting from coastal development and colony breeding disturbances from intruding humans, pet dogs, and predators.
The black skimmer breeds in mixed colonies of terns, plovers, and gulls from May through September. The breeding colonies usually include no more than 100 to 200 nests. The bird is absent from the Florida Keys during breeding season. The skimmer requires an undisturbed coastline for breeding, and it needs healthy estuaries for feeding near the nesting colony. Its prey base requires an abundance of small fish no greater than four inches long, such as needle fish, mullet, anchovies, silversides, and killifish. Shrimp are also taken.
Courtship is initiated by the male presenting a fish to the female. I have observed males presenting a substitute for a fish such as a small stick or mangrove seed capsule. The male approaches the female in a posture somewhere between submissive and threatening. Copulation or making a nest scrape ensues if the female accepts the fish (or substitute). The nest scrape is excavated by the adult turning around and around while seated in the scrape and kicking sand out backwards. The result is a shallow unlined nest scrape, usually among shells.
The female lays three to five eggs that are 1.3 inches long. The eggs are pinkish-white/buff/bluish-white in color and marked in brown. The male incubates the eggs and broods the young more than the female, but the female feeds the young and defends the nest more than the male. Incubation takes 21-23 days, and the young hatch on different days. The young are semi-precocial, meaning they are mobile, remain at the nest, and are fed. They fledge in 23-25 days. They are fed regurgitant placed on the ground. When large enough, the young are eventually given a whole fish.
Raccoons are the biggest predators of skimmer eggs and young, but foxes and rats are also culprits. Laughing gulls are the biggest avian predators of the eggs. Nesting colonies are more likely to be abandoned because of predation than high-tide flooding.
The black skimmer is protected by state and federal laws. We can help enhance all shorebird populations by avoiding their active nesting sites. Most shorebirds, especially black skimmers, are extremely sensitive while nesting and will abandon their nesting colonies when disturbed by humans.
William R. Cox has been a professional nature photographer and ecologist for more than 35 years. Visit him online at williamrcoxphotography.com.