The Crab Plover Bird (Dromas ardeola) is an AfroAsian wading bird which is remarkable for being the only representitive of the ‘Dromadidae’ family.
The Crab Plver’s relationship within the Charadriiformes is not clear, however, some have considered the bird to be closely related to the thick-knees, or the pratincoles, however, in evolutionary terms, this unique and unusual shore bird has no close living relatives.
The Crab Plover is found on the Indian Ocean coastlines and islands. The Crab Plover global population is around 60,000 – 80,000 birds observed on wintering grounds. Its distribution is very localised with only nine nesting colonies known in the world.
Use the information below to find out more about the Crab Plover’s characteristics, habitat, diet, behaviour and reproduction.
Crab Plover Characteristics
The Crab Plover measures around 33 – 36 centimetres in length. It is a very distinctive bird with a white head and plumage with a black marking on its back (mantle) and black coloring on the primary wing feathers.
The Crab Plover’s legs are long, thin and grey in color with more thickness at the knee joints and it has a short tail.
The Crab Plover has a long neck with an upright posture and a strong, long, black gull-like bill which is specialised for eating crabs and other crustaceans. Like other wading birds, the feet of the Crab Plover are only partially webbed. Males and females are practically the same in appearance except for the male’s beak which appears longer and heavier.
Crab Plover Habitat
The Crab Plover is a peculiar wading bird of tidal mudflats around Shores, coastlines and islands of the Indian Ocean. It also inhabits sandy and muddy shores on mainland coasts and islands, as well as intertidal sandflats, estuaries, lagoons and exposed coral reefs.
During breeding, this species has a specific requirement for sandy islands or extensive dunes in which nesting burrows can be excavated. At this time, Crab Plovers breed on islands in the Arabian Sea, including areas off the coasts of Somalia, Yemen, and Oman.
Outside the breeding season, they migrate to coastal regions along the Indian Ocean, including the coasts of India, Sri Lanka, and Southeast Asia, extending to the Andaman Sea and the Bay of Bengal. They also roam the shores off the east coast of Africa, and particularly Madagascar.
Crab Plover Diet
Crab Plovers flock on beaches and reefs where they hunt crabs and molluscs like cone snails and mussels. They catch their prey and break them up by pounding them with their heavy beaks. They will also take advantage of Marine Worms and Mudskippers exposed to the shore by receding tides. Crabs make up the majority of their specialised diet however.
Crab Plover Behaviour
Crab Plovers are very tame birds. They are also very noisy and give out frequent ‘calls’, particularly at their breeding sites and wintering grounds. Their usual call sounds like ‘ka ka ka ka’ which is repeated rapidly.
Flocks of Crab Plovers produce ‘whinnying’ sounds. During the breeding season a ‘kew ki ki’ can be heard. Flocks of Crab Plovers can often be observed flying in a ‘V’ formation.
Crab Plovers are gregarious birds and generally feed in large groups of 30 – 40 individuals anytime of the day or night although flocks as many as 400 can be observed outside of the breeding season. Crab Plovers are active during the day and night. This crepuscular and nocturnal behaviour is more common during the breeding season.
Crab Plover Reproduction
Crab Plovers breed during the months of April to August. Breeding grounds occur around the Arabian Sea of Pakistan, Gulf of Oman and the Persian Gulf, Red Sea and Somalia. Crab Plovers are colonial breeders and nest in colonies of up to 1500 breeding pairs. These dense colonies form around areas that have an abundance of crabs which can be fed to the young.
These mysterious shore birds have very unique breeding habits. Crab Plovers dig deep burrows and networks of interconnected burrows measuring 1.5 – 2.5 metres in sandbanks and dunes along the coast. The burrows are angled downwards and then curve upwards ending in a nest chamber a short distance from the surface. The chamber acts as insulation for the egg against very hot temperatures which occur during the breeding season and as incubation for the egg, keeping it at an optimum temperature and requiring minimum incubation from the parents. Nests can be left for up to 58 hours.
The female lays one large, single white egg into the burrow. The large egg provides sufficient energy for the developing chick during the 32 – 33 day incubation period. When the chick hatches, it is well-developed and is able to walk quite quickly although it will remain in the nest for several days after hatching. Food is brought by the parents and is mainly live crabs. Parental care from both parents is continued for a long period of time, even after the chick has fledged.
Juvenile Crab Plovers are uniform grey/brown in color, their plumage remains this color for around a year.
After the breeding season ends in August, the birds disperse across the Indian Ocean as far as the Andaman Islands and Sri Lanka in the east and Tanzania and Madagascar.
Crab Plover Predators
Larger raptors or birds of prey that inhabit coastal regions may prey on Crab Plovers, particularly their chicks and eggs. Examples include eagles, hawks, and falcons. Because they nest on the ground, burrowing into sand dunes, it’s not just the aerial threat they need to worry about, but nest predators on the ground too.
Some snakes, and monitor lizards may take any opportunity to raid eggs or chicks out of a nest, as well as foxes or other scavengers.
Crab Plover Conservation Status
The Crab Plover is classified as Least Concern on the IUCN Red List. The Crab Plover is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. Potential threats, however, are the risks of oil spills and the introduction of nest predators. Coastal development and expansion of the tourist industry could also pose threats, however, fortunately most colonies occur on small, isolated and undeveloped islands.
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