Black skimmer  (Rynchops niger)

During the 19th Century, the black skimmer population was greatly reduced due to intense egg collection and hunting for feathers and food (2) (5) (8). Although the species occurs over a large geographical range and currently has a relatively large global population (9), it still faces a number of threats. In the United States, human disturbance at breeding sites is a major cause of colony failure, with sandy beaches increasingly being used for recreation and commercial development, or suffering disturbance from people, dogs and off-road vehicles (2) (5) (8). Even slight disturbances can affect nesting success (8), reducing hatching and fledging and even causing adults to abandon the colony (5) (11). Despite being protected by law, the eggs are sometimes still taken, and in some areas the deliberate destruction of eggs and chicks and the shooting of adults is a problem (2) (5). Predators associated with humans, particularly dogs, cats and rats, may damage some colonies, and chemical pollution is also of concern, with organochlorines and heavy metals thought to accumulate in the eggs and feathers when the black skimmer feeds on contaminated fish (2). In South America, the rivers along which the black skimmer breeds are often the focus of human settlement, and increasing use of beach habitat by humans, as well as the collection of eggs and the possible depletion of fish stocks, poses a threat to many colonies (2) (3).

The black skimmer is quite adaptable in its use of feeding and nesting sites, often using man-made ponds and ditches, and breeding on gravel roofs and on areas of dredge deposition from oil exploration. However, the use of these artificial habitats results to a large extent from the black skimmer being displaced from natural beaches. Although adapted to endure natural disasters and heavy predation by readily changing colony site and re-nesting, the species is dependent on areas of open, calm water with a high concentration of fish, and so is vulnerable to any threats to fish populations, such as from oil spills or chemical pollution (2).

The future of the black skimmer is dependent on the protection of suitable breeding habitat, which is an ongoing problem as human populations expand and are increasingly attracted to beach areas. Larger colonies tend to be more stable, and can be protected by preventing development at breeding sites, restricting access by off-road vehicles, erecting fences and educational signs, and wardening to prevent egg collection and to keep dogs out (5) (8). Annual monitoring of black skimmer populations, which can easily be done from the air to minimise disturbance, has been recommended in order to provide estimates of breeding numbers, and to identify sites needing protection. Monitoring and protection are also needed for fish stocks, to ensure that the quality and quantity are maintained and that any potential effects of pollutants in the food chain identified (5) (8). In South America, it is hoped that the preservation of large stretches of river and adjacent forest to protect local fishing industries will go some way to helping protect the populations of this remarkable bird (2).