Dwarf crocodile (Osteolaemus tetraspis)

Also known as: African dwarf crocodile, broad nosed crocodile, West African dwarf crocodile
  
French: Crocodile À Front Large, Crocodile À Nuque Cuirassée, Crocodile Nain Africain
Spanish: Cocodrilo Chico Africano
KingdomAnimalia
PhylumChordata
ClassReptilia
OrderCrocodylia
FamilyCrocodylidae
GenusOsteolaemus (1)
SizeMaximum length: 1.9 m (2)

Classified as Vulnerable (VU A2 cd) by the IUCN Red List 2003 (1). Listed under Appendix I of CITES. There are two recognised subspecies: the West African dwarf crocodile O. t. tetraspis and the Congo (or Osborn’s) dwarf crocodile O. t. osborni, although recent work suggests the taxonomy may be more complex (2).

As its name suggests, the dwarf crocodile is a diminutive species, with individuals rarely reaching lengths of 1.6 m (3). It is a heavily armoured crocodile, which is dark in colour on the back and sides with a yellowish belly featuring many black patches (2). Juveniles have light brown banding on the body and tail and yellowish patterns on the head. In all individuals, the snout is short and rather blunt (2). The Congo dwarf crocodile subspecies (O. t. osborni) is poorly known. It is generally lighter in colour (2) and has a flatter and more slender snout. It may yet prove to be a separate species (5).

Found in West and West-central Africa (2), in Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Congo, Cote d’Ivorie, the Democratic Republic of Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Nigeria, Senegal, Sierra Leone and Togo (4). The West African dwarf crocodile O. t. tetraspis tends to be found in more westerly areas and the Congo dwarf crocodile O. t. osborni is, as the name suggests, found only in Congo (2).

This crocodile is found mainly in swamps and swamp forests, with a preference for slow-moving bodies of water (4). Occasionally, this species may occur in pools in savannah habitats, where they are reported to spend the dry season in burrows or hidden beneath extensive tree root structures (2). They also utilise isolated pools in forests (4).

Like all crocodilians (crocodiles, alligators, caimans and gharials), this species is an effective aquatic predator (6). It feeds on a wide range of prey, including fish, crustaceans and amphibians. It is also thought that this species may feed on some terrestrial prey species (2). The diet of the Congo dwarf crocodile tends to change throughout the year, with fish being taken in the wet season when swollen rivers bring an influx of fish into their habitats. In the dry season, they feed mainly on crustaceans (2). During the wet season, dwarf crocodiles make extensive forays on land at night (4).

Crocodiles maintain their body temperature by basking when they are cool and seeking shade when they become too hot. In the water they swim powerfully using their tails, and they walk on land using the erect “high walk” gait unique to crocodilians (6). There have been reports of galloping behaviour in this species – a bounding run back to the safety of water when threatened on land (2).

This species is generally solitary except during the breeding season (2). Females make nests from mounds of vegetation and nest building starts early on in the wet season. They lay clutches of around 10 hard-shelled eggs which take about 100 days to incubate (4). Females guard the nest and the young, which measure 28 cm in length upon hatching (2). Immediately after they hatch, the young vocalise, which stimulates the female to help the hatchlings to escape from the nest (6). Young crocodiles tend to feed on aquatic insects, crustaceans and small fish and begin to feed on more vertebrates as they increase in size (6). Typical of crocodilians, females normally reach maturity at smaller sizes than males (6).

The main threats facing this species include habitat destruction and hunting for meat for local consumption. Data collected from Congo show that tens of thousands of dwarf crocodiles are sold for food on local markets each year (4). The small size and non-aggressive nature of the dwarf crocodile makes its capture and transport relatively easy, and so it is the most heavily hunted crocodile in the area. They are either bound and transported alive to markets or killed and stored on ice (7). The hide of this species is of a relatively poor quality and so commercial hunting for this reason has not been a serious problem (4). In some countries, including Gambia and Liberia, the population of this crocodile is severely depleted, and it may soon become extinct in these areas (2). At present there is a lack of reliable survey data on this crocodile, and so the overall status of the species is unclear (2).

This species is listed under Appendix I of the Convention on International Trade in Endangered Species (CITES) and so international trade in this species is controlled (2). Plans are presently under discussion to set up captive breeding programmes for the dwarf crocodile. However, the most pressing requirement is for an extensive survey and monitoring scheme to establish the status of the species, with priority given to the countries where the species seems to be most at risk (4). Preliminary surveys were carried out in 2003 by the Wildlife Conservation Society in Congo and Gabon to examine the potential for a research programme into the ecology of the three African species of crocodile and the impact of the bushmeat trade on their populations (7).

For more on this species see:

Crocodilian.com
http://www.crocodilian.com/

Ross, J. P. (1998) Status Survey and Conservation Action Plan- Crocodiles. IUCN Species Survival Commission, Gland.
http://data.iucn.org/dbtw-wpd/edocs/1992-008.pdf

Authenticated (28/07/04) by Adam Britton, Crocodilian.com
http://www.crocodilian.com/

  1. Crocodile Specialist Group 1996. Osteolaemus tetraspis. In: IUCN 2003. 2003 IUCN Red List of Threatened Species. (March 2004):
    http://www.redlist.org
  2. Britton, A. Crocodilian.com.
    http://www.crocodilian.com/
  3. Britton, A. (July 2004) Pers. comm.
  4. News about Congo dwarf crocodiles. Crocodile Specialist Group Newsletter vol 22, (no.1) January-March 2003: pp. 3-6. WWW Edition:
    http://www.flmnh.ufl.edu/natsci/HERPETOLOGY/NEWSLETTER/news223p3-11.htm
  5. IUCN Species Survival Commission Crocodile Specialist Group. Crocodilian Action Plan. (March 2004):
    http://www.flmnh.ufl.edu/herpetology/act-plan/otetr.htm
  6. Ross, J. P. (1998) Status Survey and Conservation Action Plan- Crocodiles. IUCN Species Survival Commission, Gland. (Downloaded March 2004):
    http://data.iucn.org/dbtw-wpd/edocs/1992-008.pdf
  7. Thorbjarnarson, J. & Eaton, M. (2003) Congo and Gabon Crocodile surveys. Crocodile Specialist Group Newsletter vol 22 (no.1) January-March 2003: pp 3-11- WWW Edition:
    http://www.flmnh.ufl.edu/natsci/HERPETOLOGY/NEWSLETTER/news223p3-11.htm