Mugger crocodile


The mugger crocodile is a medium-sized broad-snouted crocodile, also known as mugger and marsh crocodile. It is native to freshwater habitats from south-eastern Iran to the Indian subcontinent, where it inhabits marshes, lakes, rivers and artificial ponds. It rarely reaches a body length of and is a powerful swimmer, but also walks on land in search of suitable waterbodies during the hot season. Both young and adult mugger crocodiles dig burrows to which they retreat when the ambient temperature drops below or exceeds. Females dig holes in the sand as nesting sites and lay up to 46 eggs during the dry season. The sex of hatchlings depends on temperature during incubation. Both parents protect the young for up to one year. They feed on insects, and adults prey on fish, reptiles, birds and mammals.
The mugger crocodile evolved at least and has been a symbol for the fructifying and destructive powers of the rivers since the Vedic period. It was first scientifically described in 1831 and is protected by law in Iran, India and Sri Lanka. Since 1982, it has been listed as Vulnerable on the IUCN Red List. Outside protected areas, it is threatened by conversion of natural habitats, gets entangled in fishing nets and is killed in human–wildlife conflict situations and in traffic accidents.

Taxonomy and evolution

Crocodilus palustris was the scientific name proposed by René Lesson in 1831 who described the type specimen from the Gangetic plains. In subsequent years, several naturalists and curators of natural history museums described zoological specimens and proposed different names, including:
analysis of 23 crocodilian species indicated that the genus Crocodylus most likely originated in Australasia about. The freshwater crocodile is thought to have been the first species that genetically diverged from the common ancestor of the genus about. The sister group comprising saltwater crocodile, Siamese crocodile and mugger crocodile diverged about. The latter diverged from this group about.
A paleogenomics analysis indicated that Crocodylus likely originated in Africa and radiated towards Southeast Asia and the Americas, diverging from its closest recent relative, the extinct Voay of Madagascar, around near the Oligocene/Miocene boundary.
Within Crocodylus, the mugger crocodile's closest living relatives are the Siamese crocodile and the saltwater crocodile.
Fossil crocodile specimens excavated in the Sivalik Hills closely resemble the mugger crocodile in the shortness of the premaxillae and in the form of the nasal openings. In Andhra Pradesh's Prakasam district, a long fossilized skull of a mugger crocodile was found in a volcanic ash bed that probably dates to the late Pleistocene. Crocodylus palaeindicus from late Pliocene sediments in the Sivalik Hills is thought to be an ancestor of the mugger crocodile. Fossil remains of C. palaeindicus were also excavated in the vicinity of Bagan in central Myanmar.
Below cladogram is from a tip dating study, for which morphological, molecular DNA sequencing and stratigraphic fossil age data were simultaneously used to establish the inter-relationships within Crocodylidae. This cladogram was revised in a paleogenomics study.

Characteristics

Mugger crocodile hatchlings are pale olive with black spots. Adults are dark olive to grey or brown. The head is rough without any ridges and has large scutes around the neck that is well separated from the back. Scutes usually form four, rarely six longitudinal series and 16 or 17 transverse series. The limbs have keeled scales with serrated fringes on outer edges, and outer toes are extensively webbed. The snout is slightly longer than broad with 19 upper teeth on each side. The symphysis of the lower jaw extends to the level of the fourth or fifth tooth. The premaxillary suture on the palate is nearly straight or curved forwards, and the nasal bones separate the premaxilla above.
The mugger crocodile is considered a medium-sized crocodilian, but has the broadest snout among living crocodiles. It has a powerful tail and webbed feet. Its visual, hearing and smelling senses are acute. Adult female muggers are on average; males usually measure, but rarely reach a length of. The two largest known muggers measured and were killed in Sri Lanka.
One individual weighing had a bite force of. Large males may reach a weight of.
The largest zoological specimen in the British Museum of Natural History measures. One male mugger caught in Pakistan of about weighed.

Distribution and habitat

The mugger crocodile occurs in southern Iran, Pakistan, Nepal, India and Sri Lanka up to an elevation of. It inhabits freshwater lakes, rivers and marshes, and prefers slow-moving, shallow water bodies. It also thrives in artificial reservoirs and irrigation canals.
In Iran, the mugger occurs along rivers in Sistan and Baluchestan Provinces along the Iran–Pakistan border. A population of around 200 mugger crocodiles lives on the Iranian Makran coast near Chabahar. Due to human activity and a long drought in the late 1990s and early 2000s, it had been pushed to the brink of extinction. Following several tropical cyclones in 2007 and 2010, much of the habitat of the mugger crocodiles has been restored as formerly dry lakes and hamuns were flooded again.
In Pakistan, a small population lives in 21 ponds around Dasht River; in the winter of 2007–08, 99 individuals were counted. By 2017, the population had declined to 25 individuals. In Sindh Province, small mugger populations occur in wetlands of Deh Akro-2 and Nara Desert Wildlife Sanctuary, near Chotiari Dam, in the Nara Canal and around Haleji lake.
In Nepal's Terai, it occurs in the wetlands of Shuklaphanta and Bardia National Parks, Ghodaghodi Tal, Chitwan National Park and Koshi Tappu Wildlife Reserve.
In India, it occurs in:
In Sri Lanka, it occurs in Wilpattu, Yala and Bundala National Parks. Between 1991 and 1996, it was recorded in another 102 localities.
In Bangladesh, it was historically present in the northern parts of the Sundarbans, where four to five captive individuals survived in an artificial pond by the 1980s. It is possibly locally extinct in the country.
In Bhutan, it became extinct in the late 1960s, but a few captive-bred individuals were released in the Manas River in the late 1990s. It is considered locally extinct in Myanmar.

Behaviour and ecology

The mugger crocodile is a powerful swimmer that uses its tail and hind feet to move forward, change direction and submerge. It belly-walks, with its belly touching ground, at the bottom of waterbodies and on land. During the hot dry season, it walks over land at night to find suitable wetlands and spends most of the day submerged in water. During the cold season it basks on riverbanks, individuals are tolerant of others during this period. Territorial behaviour increases during the mating season.
Like all crocodilians, the mugger crocodile is a thermoconformer and has an optimal body temperature of and risks dying of freezing or hyperthermia when exposed to temperatures below or above, respectively. It digs burrows to retreat from extreme temperatures and other harsh climatic conditions. Burrows are between deep, with entrances above the water level and a chamber at the end that is big enough to allow the mugger to turn around. Temperatures inside remains constant at, depending on region.

Hunting and diet

The mugger crocodile preys on fish, snakes, turtles, birds and mammals including monkeys, squirrels, rodents, otters and dogs. It also scavenges on dead animals. During dry seasons, muggers walk many kilometers over land in search of water and prey. Hatchlings feed mainly on insects such as beetles, but also on crabs and shrimp and on vertebrates later on. It seizes and drags potential prey approaching watersides into the water, when the opportunity arises. Adult muggers were observed feeding on a flapshell turtle and a tortoise. Subadult and adult muggers favour fish, but also prey on small to medium-sized ungulates up to the size of chital.
At the Chambal River, muggers have attacked water buffaloes, cattle and goats.
In Bardia National Park, a mugger was observed caching a chital kill beneath the roots of a tree and returning to its basking site; a part of the deer was still wedged among the roots on the next day. In the same national park, a mugger caught a brown fish owl ; several instances of water bird feathers in mugger dung have been reported.
Muggers have also been observed preying and feeding on pythons.
In Yala National Park, a mugger killed a large Indian pangolin and devoured pieces over several hours.