Themugger crocodile (Crocodylus palustris) is a medium-sized broad-snoutedcrocodile, also known asmugger andmarsh crocodile. It is native tofreshwater habitats from south-easternIran to theIndian subcontinent, where it inhabitsmarshes,lakes,rivers and artificialponds. It rarely reaches a body length of 5 m (16 ft 5 in) 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 digburrows to which they retreat when the ambient temperature drops below 5 °C (41 °F) or exceeds 38 °C (100 °F). Females dig holes in the sand as nesting sites and lay up to 46eggs during the dry season. The sex ofhatchlings depends on temperature duringincubation. Both parents protect the young for up to one year. They feed oninsects, and adults prey onfish,reptiles,birds andmammals.
The mugger crocodile evolved at least4.19 million years ago and has been a symbol for the fructifying and destructive powers of the rivers since theVedic 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 asVulnerable on theIUCN Red List. Outsideprotected areas, it is threatened by conversion of natural habitats, gets entangled infishing nets and is killed inhuman–wildlife conflict situations and in traffic accidents.
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 largescutes 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 havekeeled scales withserrated fringes on outer edges, and outer toes are extensively webbed. The snout is slightly longer than broad with 19 upper teeth on each side. Thesymphysis of thelower jaw extends to the level of the fourth or fifth tooth. Thepremaxillarysuture on thepalate is nearly straight or curved forwards, and thenasal bones separate the premaxilla above.[18]
The mugger crocodile is considered a medium-sized crocodilian, but has the broadestsnout amongliving crocodiles.[19] It has a powerful tail and webbed feet. Itsvisual,hearing andsmelling senses are acute. Adult female muggers are 2 to 2.5 m (6 ft 7 in to 8 ft 2 in) on average; males usually measure 3 to 3.5 m (9 ft 10 in to 11 ft 6 in), but rarely reach a length of 5 m (16 ft 5 in). The two largest known muggers measured 5.63 m (18 ft 6 in) and were killed in Sri Lanka.[20]One individual weighing 207 kg (456 lb) had abite force of 7,295 N (1,640 lbf).[21] Large males may reach a weight of 450 kg (1,000 lb).[22]
The mugger crocodile occurs in southern Iran, Pakistan, Nepal, India and Sri Lanka up to an elevation of 420 m (1,380 ft).[2] It inhabits freshwater lakes, rivers and marshes, and prefers slow-moving, shallow water bodies. It also thrives in artificialreservoirs andirrigationcanals.[19]
In Iran, the mugger occurs along rivers inSistan and Baluchestan Provinces along theIran–Pakistan border.[2] A population of around 200 mugger crocodiles lives on the IranianMakran coast nearChabahar. Due to human activity and a longdrought in the late 1990s and early 2000s, it had been pushed to the brink ofextinction. Following severaltropical cyclones in 2007 and 2010, much of the habitat of the mugger crocodiles has been restored as formerly dry lakes andhamuns were flooded again.[24]
InBangladesh, it was historically present in the northern parts of theSundarbans, where four to five captive individuals survived in an artificial pond by the 1980s.[51] It is possiblylocally extinct in the country.[52]InBhutan, it became extinct in the late 1960s, but a few captive-bred individuals were released in theManas River in the late 1990s.[34] It is considered locally extinct inMyanmar.[2]
Behaviour and ecology
Mugger walking, Sri Lanka
Muggers basking on sand banks
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.[20]
Like all crocodilians, the mugger crocodile is athermoconformer and has an optimal body temperature of 30 to 35 °C (86 to 95 °F) and risks dying of freezing orhyperthermia when exposed to temperatures below 5 °C (41 °F) or above 38 °C (100 °F), respectively. It digs burrows to retreat from extreme temperatures and other harsh climatic conditions.[53] Burrows are between 0.6 and 6 m (2.0 and 19.7 ft) deep, with entrances above the water level and a chamber at the end that is big enough to allow the mugger to turn around.[20] Temperatures inside remains constant at 19.2 to 29 °C (66.6 to 84.2 °F), depending on region.[49]
Hunting and diet
The mugger crocodile preys on fish,snakes,turtles, birds and mammals includingmonkeys,squirrels,rodents,otters anddogs. It alsoscavenges on dead animals. During dry seasons, muggers walk many kilometers over land in search of water and prey.[54] Hatchlings feed mainly on insects such asbeetles, but also oncrabs andshrimp and onvertebrates later on.[55][56] It seizes and drags potential prey approaching watersides into the water, when the opportunity arises. Adult muggers were observed feeding on aflapshell turtle and atortoise.[57][58] Subadult and adult muggers favour fish, but also prey on small to medium-sizedungulates up to the size ofchital (Axis axis).[59]At the Chambal River, muggers have attackedwater buffaloes,cattle andgoats.[60]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.[30] In the same national park, a mugger caught abrown fish owl (Ketupa zeylonensis); several instances ofwater bird feathers in mugger dung have been reported.[61]Muggers have also been observed preying and feeding onpythons.[56] InYala National Park, a mugger killed a largeIndian pangolin (Manis crassicaudata) and devoured pieces over several hours.[62]
Tool use
Mugger crocodiles have been documented using lures to hunt birds.[63] This means they are among the first reptiles recorded touse tools. By balancing sticks and branches on their heads, they lure birds that are looking for nesting material. This strategy is particularly effective during the nesting season.[64]
Reproduction
Female muggers obtainsexual maturity at a body length of around 1.8–2.2 m (5 ft 11 in – 7 ft 3 in) at the age of about 6.5 years, and males at around 2.6 m (8 ft 6 in) body length. Thereproduction cycle starts earliest in November at the onset of the cold season with courtship and mating. Between February and June, females dig 35–56 cm (14–22 in) deep holes for nesting between 1 and 2,000 m (3 ft 3 in and 6,561 ft 8 in) away from the waterside. They lay up to twoclutches with 8 –46 eggs each. Eggs weigh 128 g (4.5 oz) on average. Laying of one clutch usually takes less than half an hour. Thereafter, females scrape sand over the nest to close it. Males have been observed to assist females in digging and protecting nest sites. Hatching season is two months later, between April and June in south India, and in Sri Lanka between August and September. Then females excavate the young, pick them up in their snouts and take them to the water. Both females and males protect the young for up to one year.[20][54]
Healthy hatchlings develop at a temperature range of 28–33 °C (82–91 °F). Sex ratio of hatched eggs depends on incubation temperature and exposure of nests to sunshine. Only females develop at constant temperatures of 28–31 °C (82–88 °F), and only males at 32.5 °C (90.5 °F). Percentage of females in a clutch decreases at constant temperatures between 32.6 and 33 °C (90.7 and 91.4 °F), and of males between 31 and 32.4 °C (87.8 and 90.3 °F). Temperature in natural nests is not constant but varies between nights and days. Foremost females hatch in natural early nests when initial temperature inside nests ranges between 26.4 and 28.9 °C (79.5 and 84.0 °F). The percentage of male hatchlings increases in late nests located in sunny sites.[65] Hatchlings are 26–31 cm (10–12 in) long and weigh 75 g (2.6 oz) on average when one month old. They grow about 4.25 cm (1.67 in) per month and reach a body length of 90–170 cm (35–67 in) when two years old.[20]
TheBengal tiger (Panthera tigris tigris) occasionally fights mugger crocodiles off prey and rarely preys on adult mugger crocodiles in Ranthambore National Park.[72] TheAsiatic lion (Panthera leo leo) sometimes preys on crocodiles on the banks of theKamleshwar Dam inGir National Park during dry, hot months.[73]
Threats
The mugger crocodile is threatened byhabitat destruction because of conversion of natural habitats for agricultural and industrial use. As humans encroach into its habitat, the incidents of conflict increase. Muggers are entangled in fishing equipment and drown, and are killed in areas where fishermen perceive them as competition.[2]Major wetlands in Pakistan weredrained in the 1990s by dams and channels to funnel natural streams andagricultural runoffs into rivers.[34]
In Gujarat, two muggers were found killed, one in 2015 with the tail cut off and internal organs missing; the other in 2017, also with the tail cut off. The missing body parts indicate that the crocodiles were sacrificed insuperstitious practices or used asaphrodisiacs.[74]Between 2005 and 2018, 38 mugger crocodiles were victims of traffic accidents on roads and railway tracks in Gujarat; 29 were found dead, four died during treatment, and five were returned to the wild after medical care.[36] In 2017, a dead mugger was found on a railway track in Rajasthan.[75]
Conservation
The mugger crocodile is listed inCITES Appendix I, hence international commercial trade is prohibited. It has been listed as Vulnerable on the IUCN Red List since 1982. By 2013, less than 8,700 mature individuals were estimated to live in the wild and no population unit to comprise more than 1,000 individuals.[2]
In India, it has been protected since 1972 under Schedule I of theWildlife Protection Act, 1972, which prohibits catching, killing and transporting a crocodile without a permit; offenders faceimprisonment and afine.[67]In Sri Lanka, it was listed in Schedule IV of the Fauna & Flora Protection Ordinance in 1946, which allowed for shooting one crocodile with a permit. Today, it is strictly protected, butlaw enforcement in Sri Lanka is lacking.[76]In Iran, the mugger crocodile is listed as endangered and has been legally protected since 2013; capturing and killing a crocodile is punished with a fine of 100 millionIranian rials.[77]
Since large muggers occasionally takelivestock, this leads to conflict with local people living close to mugger habitat. In Maharashtra, local people are compensated for loss of close relatives and livestock.[56][78] Local people in Baluchestan respect the mugger crocodile as a water living creature and do not harm it. If an individual kills livestock, the owner is compensated for the loss. The mugger crocodile istranslocated in severe conflict cases.[77]
A total of 1,193 captive bred muggers were released to restock populations in 28 protected areas in India between 1978 and 1992. Production of new offspring was halted by the Indian Government in 1994.[2]
TheSanskrit wordमकर (makara) refers to the crocodile and a mythical crocodile-like animal.[79] TheHindi word for crocodile isमगर (magar).[80] In English language, both names mugger and magar were used around the turn of the 20th century.[81][82][83] The names 'marsh crocodile' and 'broad-snouted crocodile' have been used since the late 1930s.[84]
The traditional biography of the Indian saintAdi Shankara includes an incident where he is grabbed by a crocodile in theKaladi river, which releases him only after his mother reluctantly let him choose the ascetic path of aSannyasa.[88] TheMuslim saintPīr Mango is said to have taken care of crocodiles and created a stream to trickle out of a rock nearKarachi in the 13th century. This place was later walled around, and about 40 mugger crocodiles were kept in the reservoir called Magar Talao in the 1870s; they were fed by bothHindu and Muslimpilgrims.[89] Mugger crocodiles have also been kept in tanks nearHindu temples built in the vicinity of rivers; these crocodiles are consideredsacred. In the early 20th century, young married women fed the crocodiles inKhan Jahan Ali's Tank inJessore in the hope of being blessed with children.[90]
Vasava,Gamit and Chodhritribes in Gujaratworship the crocodile god Mogra Dev asking for children, good crops andmilk yield of their cows. They carve wooden statues symbolising Mogra Dev and mount them on poles. Their offerings during the installationceremony includerice, milk, wine, heart and liver of a chicken, and a mixture ofvermillion,oil andcoconut fibres.[91] Fatal attacks of mugger crocodiles on humans were documented in Gujarat and Maharashtra, but they rarely consumed the victims who died ofdrowning.[92]
A fable from theJataka tales of Buddhist traditions features a clever monkey outwitting a crocodile.[93] Three folktales feature crocodiles andjackals.[94][95][96] A mugger crocodile is one of the characters inThe Undertakers, a chapter ofThe Second Jungle Book.[81] Thechildren’s bookAdventures of a Nepali Frog features the character Mugger, the crocodile who lives by the Rapti River in Chitwan National Park.[97]
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