Crocodylus novaeguineae

New Guinea crocodile
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Crocodilia
Family:	Crocodylidae
Genus:	Crocodylus
Species:	C. novaeguineae
Binomial name
Crocodylus novaeguineae (Schmidt, 1928)

The New Guinea crocodile (Crocodylus novaeguineae) is a small species of crocodile found on the island of New Guinea where there are two geographically isolated populations. Its habitat is mostly freshwater swamps and lakes and it is most active at night when it feeds on fish and a range of other small animals. A female crocodile lays a clutch of eggs in a nest composed of vegetation and she lies up nearby to guard the nest. There is some degree of parental care for newly hatched juveniles. This crocodile was over-hunted for its valuable skin in the mid 20th century, but conservation measures have been put in place, it is reared in ranches and the International Union for Conservation of Nature (IUCN) lists it as being of "Least Concern".

Taxonomy and etymology

The New Guinea crocodile was first described by the American herpetologist Karl Patterson Schmidt in 1928 as Crocodylus novaeguineae.^[1] At one time it was thought that there were two subspecies, C. n. novaeguineae, the New Guinea crocodile native to Papua New Guinea, and C. n. mindorensis, the Philippine crocodile, native to several islands including Busuanga, Luzon, Masbate, Mindoro, Negros, Samar and Mindanao. Most authorities now consider that the Philippine crocodile is an entirely separate species.^[2]

The genus name Crocodylus comes from the Greek kroko which means a pebble and deilos, a worm or man, referring to the knobbly appearance of the dorsal surface of the reptile. The specific epithet novaeguineae is from the Latin and means "of New Guinea". Other common names for this crocodile include New Guinea freshwater crocodile, Singapore large grain, Puk Puk, Buaya air tawar and Wahne huala.^[2]

Characteristics

Crocodylus novaeguineae grows to a length of up to 3.5 m (11 ft) for males and 2.7 m (8.9 ft) for females, although most specimens are smaller.^[3] The body is gray-brown in colour, with dark brown or black bandings on the tail which become less noticeable as the animal grows. The snout is pointed and relatively narrow during juvenile stages and becomes wider as the animal matures. It bears a physical similarity to the nearby Philippine crocodile (C. mindorensis) and Siamese crocodile (C. siamensis). The colouring is similar to that of the freshwater crocodile (Crocodylus johnsoni) of northern Australia but the snout is somewhat shorter and broader.^[2][4]

Distribution and habitat

This primarily nocturnal crocodile is to be found in the freshwater swamps and lakes of New Guinea, particular in the interior. Although tolerant of saltwater, it is rarely to be found in brackish coastal waters, and never in the presence of the competing saltwater crocodile (C. porosus).^[2] Two populations of C. novaeguineae are known on the island, separated by the mountain range that runs along the centre of the island. The animal was first described from the Sepik River area in the north of Papua New Guinea but a separate population is found in the south of the island in the Indonesian provinces of Papua and West Papua.^[4] DNA analysis has revealed these to be genetically separate populations.^[5]

Behaviour

New Guinea crocodiles have a largely aquatic lifestyle. They spend much of the day underwater, often with their nostrils and eyes above the surface. Powerful side-to-side movements of their tails propel them through the water and they use both tail and legs to steer. When on land, they favour shady, dense areas of undergrowth.^[2] They tend to bask in a group during the day, dispersing at night to feed.^[4]

Females become sexually mature when about 1.6 to 2 metres (5 ft 3 in to 6 ft 7 in) long and males at about 2.5 metres (8 ft 2 in). Eggs are laid about 14 days after mating. In the northern population, breeding takes place during the dry season and a floating nest composed of vegetation is made in an overgrown, shallow water location. A clutch of between 22 and 45 eggs is laid and covered with further vegetation. In the southern population, the wet season is chosen for reproduction. A similar nest is built on land and a smaller number of rather larger eggs is laid. In both cases, the mother stays near the nest during the incubation period, which lasts about 80 days. When the eggs start to hatch the emerging young are quite vocal, and both male and female crocodiles have been observed transporting hatching and newly hatched young to open water, carrying them delicately in their mouths.^[2][4]

Newly hatched New Guinea crocodiles feed on aquatic insects, spiders, tadpoles, freshwater snails, frogs, fish and small mammals. As they grow, so does the size of their prey and their consumption of fish rises, but they still will eat anything of a worthwhile size that they can find. An adult's diet is largely fish, caught by sweeping the snout sideways and snapping at the prey, but also includes shrimps, crabs, frogs, snakes, birds and medium-sized mammals. A crocodile catches its prey by stealth with a flick of its head, impaling it with its sharp canines and gripping and crushing it with its molars. The jaws cannot move sideways to chew the food; instead, the crocodile's head is tossed to move the prey to the back of the mouth before the prey is swallowed whole. This crocodile is surprisingly agile and can lunge its body upward into the air to catch bats, flying birds, and leaping fish.^[4] It can also probe into the mud at the bottom of river or swamp with its snout to search for crabs and molluscs.^[4]

Adult and young New Guinea crocodiles have a range of vocalisations. An adult female can produce a repeated throaty "roar" when approached by another adult. The young start communicating with each other while still in the egg; this may help synchronise hatching. Newly hatched juveniles use various yelps and grunts. When startled, a warning sound emitted by one will send all the juveniles diving to the bottom of the water. Adults in the vicinity respond with growls, threats, and attacks.^[4] The distress noises of a youngster when handled at a ranching facility was observed to cause all the larger animals to become involved in frenzied activity, with some rushing towards the juvenile and others thrashing about in the water and slapping their heads down on the surface.^[4]

Status and conservation

The IUCN listed this crocodile as being "Vulnerable" in its Red List of Threatened Species in 1986 and 1988, but changed the assessment to "Least Concern" in 1996. At the time it was stated that the animal has a large area of suitable habitat and seemed to be plentiful. Its status has not been reassessed since then. It is included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).^[6]

The skin of the New Guinea crocodile is valuable and in the 1950s and 1960s the animals in the northern population were heavily hunted to a point where they might have become extinct. Around 1970, legislation was put in place and they received some protection. Since then, cropping has been controlled and a ranching programme has been initiated. Some eggs and hatchlings are removed from the nest and raised in enclosures. A similar programme has more recently been initiated for southern populations.^[2]

References

External links

• Crocodylus novaeguineae at the Encyclopedia of Life

Wikispecies has information related to: Crocodylus novaeguineae

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