The breeding adult black skimmer has brown-black upperparts, contrasting with a white forehead and underparts. The upperwing shows a white trailing edge from the secondaries to the inner primaries. The tail is white, with dark central feathers. The bill is black with a reddish-orange base. The legs and feet are also reddish-orange. Male black skimmers are slightly larger than females. Nonbreeding adult plumage is similar, but duller, to that of breeding adults. In winter, the bill and upperparts are somewhat paler. In addition, white feathers on the nape form a light collar around the neck. Juvenile skimmers appear similar to adults, but have duller brown upperparts with light feather edges and streaked crowns. The legs, feet, and base of the bill are dusky-red. Juveniles acquire adult-like plumage the following summer.
The black skimmer nests on open sandy beaches, inlets, sandbars, offshore islands, and dredge disposal islands that are sparsely vegetated and contain shell fragments. The growth of dense vegetation may cause colony relocation. Skimmers also frequently nest on wrack mats (deposits of dead sea grasses and other vegetation) on marsh islands in the back bays; however, these colonies are typically much smaller than the beach colonies. Black skimmers forage in shallow-water tidal creeks, inlets, and ponds. Similar coastal and estuarine habitats are used throughout the year.
Breeds from southern California (west)and New York (east)south to southern South America along coasts and on major river systems; winters in southern temperate and tropical portions of breeding range, West Indies. Common in Suriname along the coast on sand- and mudbanks. Often seen along the Weg naar Zee near Paramaribo. Most likely a non-breeder, a nest have never been recovered.
Black skimmer feeds by skimming the surface of the water, with its specific bill. They feed in large flocks. Black skimmer flies low over the water, the lower mandible skimming the surface for small fishes and crustaceans. When it catches a prey, it bows the head and closes its bill. Then, it bends its beak below the body before to rise higher to turn its prey and swallow it in flight. When it is skimming, its lower mandible makes an angle of almost 45 degrees with the upper, which is elevated a little above the surface. They feed mainly under low wind, when the surface is quiet. It feeds especially from dusk to dawn because it is highly nocturnal. It spends the whole night on wing, searching for food. Black skimmer feeds mainly on small fishes and also crustaceans.
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern. [conservation status from birdlife.org]
Black skimmers begin a courtship process once they arrive at a breeding colony. They form dense flocks and form pairs within about one week. Though individuals may change location in the group more than once, males and females are usually paired within a few days and establish territories. They are monogamous and males aggressively protect their mates. Black skimmers exhibit courtship feeding usually during the evening hours. In this process, a male will present a fish to the female. Once the female accepts the fish and holds it in her beak, the male mounts her and copulation occurs. The female will hold the fish in her beak during copulation and swallow the fish afterward. This is a distinct difference between black skimmers and terns, where females usually eat the fish before copulation. If a male cannot find his mate a fish, he may still be successful in courting her by presenting a stick or a leaf. Copulation may occur several times a day.
Black skimmer's nest is only a shallow depression in the sand. Black skimmer breeds on beaches, in loose colonies. They turn in the scrape to create a cup-shaped depression, where no materials are added. During nest building, pair makes turns scraping, with exaggerated posture, neck, head, bill and tail erected, with alternate foot strokes that eject sand backwards. Nest building needs 5 to 7 days.
Female lays 4 to 5 white eggs, largely blotched with black and with some purplish brown spots. Incubation lasts about 21 to 23 days, or 25 days if disturbed. Incubation is only by female.
Young appear on the same colour as the sand, and they are not able to fly before 6 weeks, but they fledge at 23 to 25 days, and they lie flat in the sand, in depressions that they scrape themselves. At hatching, chicks have their mandibles equal in length.
Both parents feed them by regurgitation, and at the end, they pick up shrimps, prawns, small crabs and fishes dropped before them. Young reach their sexual maturity at 2 years old. When they are gorged and tired, both, parents and young, lie flat on the sand, with their bills extended before them.
Migratory. Northernmost breeding zones vacated November-Marcch, birds wintering scantily South from North Carolina, and in greater number South from South Carolina to Florida, and down Gulf coast and both coasts of Mexico to Panama. Sometimes carried far afield by storms, e.g. to Newfoundland, inland USA and Mexico, West Indies and Venezuela. Non-breeding cinerascens arrive in Chile in October, leaving in May; present in Trinidad May-November. Non- breeding intercedes on coast and estuaries mainly December-May, but poorly documented.