West African Dwarf Crocodile

The dwarf crocodile is the smallest living species of crocodile, with adults reaching 1.7 to 1.9 m. It lives in streams, small rivers, swamps, pools and mangrove across West and Central Africa, within the equatorial rainforest belt. Dark above with a yellowish, black-patched underside, it has heavy armour on its neck, back, tail and belly. A timid, mainly nocturnal animal, it spends the day hidden in pools or burrows. It feeds on fish, crabs, frogs, snails and many other small animals, shifting from fish in the wet season to crustaceans in the dry season in the Congo. Females build nest mounds of decaying vegetation.

About the West African dwarf crocodile

The dwarf crocodile is the smallest living crocodile, a short-snouted, heavily armored species of the rainforest streams and swamps of West and Central Africa. It belongs to the true crocodile family, in the subfamily Osteolaeminae. Adults reach only 1.7 to 1.9 m (5.6 to 6.2 ft) long and 18 to 32 kg (40 to 71 lb).

Its scientific name is Osteolaemus tetraspis. It is also called the African dwarf crocodile, the bony crocodile and the broad-snouted crocodile, although that last name is more often used for the Asian mugger. The genus name means "bony throat," for the bony plates (osteoderms) in the skin of its neck and belly. The species name means "four shields," for four large shield-like scales on the back of the neck.

Its small size leaves it open to many predators, and its armor reflects that. The neck, back and tail are heavily armored, and it also has osteoderms on the belly and the underside of the neck. The snout is blunt and short, about as long as it is wide, much like the snout of Cuvier's dwarf caiman of South America, probably because the two fill similar niches. Among all crocodilians, only Cuvier's dwarf caiman, at up to about 1.7 m (5.6 ft), is smaller.

Adults are dark on the back and sides, with a yellowish belly marked with black patches. Juveniles have lighter brown bands on the body and tail and yellow markings on the head. Some crocodiles living in caves at Abanda in Gabon have orange patches, apparently because alkaline bat guano wears away at their skin.

Behavior and diet

The dwarf crocodile is timid, solitary and mainly nocturnal. It spends the day hidden in pools or in a burrow it digs itself, sometimes with an underwater entrance. Where it can't dig, it shelters among tree roots hanging over the water. Unlike most crocodiles, it only rarely basks in the sun.

It is considered one of the most land-loving crocodilians. Most feeding happens in or near water, but it may make long forays over land, especially after rain, and may travel some distance from water at night. During the dry season it often retreats into deep holes, and it can go relatively long periods without food.

Dwarf crocodiles are generalist predators of small animals. Recorded prey includes fish, crabs, shrimp, snails, frogs, millipedes, spiders, insects, young monitor lizards, water birds, bats and shrews. Diet varies by place and season. In one Democratic Republic of the Congo study fish were the main food, switching to crustaceans in the dry season when fish are scarce; in Nigeria, snails and crabs topped the list.

Adults interact closely only during breeding. At the start of the wet season, in roughly April to June, the female builds a mound nest of wet, rotting vegetation near the water. Heat from the decomposing plants incubates the eggs. Clutches are small for a crocodile, usually about 10 eggs and at most about 20, and they take 85 to 105 days to hatch.

The female guards the nest throughout incubation and stays with the hatchlings for some time afterward. That protection matters: the 28 cm (11 in) young are eaten by birds, fish, mammals and reptiles, including other crocodiles.

Range and habitat

Dwarf crocodiles live across the tropical belt of West and Central Africa, in the equatorial rainforest. The range reaches west to Senegal, east to Uganda and south to Angola, closely overlapping that of the slender-snouted crocodile. Uganda's last confirmed record dates from the 1940s, and it is unclear whether the easily overlooked species still survives there.

They live in streams, small rivers, swamps, pools and mangroves from lowlands to mid-elevations, generally avoiding the main channels of large rivers. Most of the range is forested, but they extend into more open country where streams are well shaded, and into seasonally flooded forest. Some have been reported in isolated savanna pools. Crocodiles living long-term in caves in western Gabon form a genetically isolated group.

West African dwarf crocodile vs Congo dwarf crocodile

Dwarf crocodile taxonomy is unsettled. DNA studies suggest at least three distinct populations that may deserve species status: O. tetraspis in Central Africa outside the Congo Basin, O. osborni in the Congo Basin, and a possibly unnamed species in West Africa. Captive dwarf crocodiles in North America are mostly O. tetraspis and the West African form, along with some hybrids.

If O. osborni is recognized as a full species, it would become both the smallest crocodile and the smallest crocodilian of all.

Conservation status

The dwarf crocodile is listed as Vulnerable on the IUCN Red List, in an assessment dating to 1996, and it is listed on CITES Appendix I. It is little studied, so conservationists often know less about how its populations are faring than they do for other crocodilians.

Where survey data exist, they show some decline from hunting for bushmeat and from habitat loss due to deforestation. The species is widespread and presumably numerous overall, and some regional populations remain healthy. In others, such as Gambia and Liberia, it has seriously declined and may be at risk of disappearing. It occurs in several protected reserves.

Its skin makes poor-quality leather, so there is little commercial interest in farming it, but it is hunted for food. Dwarf crocodiles are widely kept and bred in captivity, though genetic studies show captive groups include several lineages and some hybrids.