Crocodylus palustris

Common names: Mugger, muggar, marsh crocodile Range: Bangladesh, Iran, India, Nepal, Pakistan, Sri Lanka

CITES: Appendix I
CSG Action Plan: Availability of Survey Data – Poor
Need for Wild Population Recovery – High
Potential for Sustainable Management – Moderate
1996 IUCN Red List: VU Vulnerable – Criteria: A.1.a. decline of 20% in 3 generations in extent of occurrence. C.2.a. Wild population less than 2,500 adults and habitat fragmented and declining.
Principal threats: Habitat destruction.

Ecology and natural history

The mugger is a medium-sized crocodile (maximum length ca. 4–5m), and has the broadest snout of any living member of the genus Crocodylus. Muggers are principally restricted to the Indian subcontinent where they may be found in a number of freshwater habitat types including rivers, lakes and marshes. In India and Sri Lanka, mugger crocodiles have adapted well to reservoirs, irrigation canals and man made ponds, and in some areas may even be found in coastal saltwater lagoons (Whitaker 1987, Whitaker and Whitaker 1989). In some areas of northern India and Nepal, mugger populations are sympatric with gharial, but the two species tend to be segregated by habitat. Where found together with gharial, muggers tend to bask in midstream on rocks or muddy banks (Groombridge 1982). This species, like a number of other crocodilians, is known to dig burrows.

Mugger crocodiles are a hole nesting species. As with other hole nesters, egg laying takes place during the annual dry season. Females become sexually mature at a length of approximately 1.8–2m, and lay 25–30 eggs (Whitaker and Whitaker 1989). Nests are located in a wide variety of habitats, and females have even been known to nest at the opening of, or inside, the burrow (B.C. Choudhury, pers. comm.). In captivity, some mugger crocodiles are known to lay two clutches in a single year (Whitaker and Whitaker 1984), but this has not been observed in the wild. Incubation is relatively short, typically lasting 55–75 days (Whitaker 1987). Whitaker and Whitaker (1989) provide a good review of the behavior and ecology of this species.

Conservation and status

While illegal skin trade was a major problem in the past (1950s–1960s), the current threats to the mugger crocodile are principally habitat destruction, drowning in fish nets, egg predation by people, and the use of crocodile parts for medicinal purposes (Groombridge 1982). Adequate survey data exist only for India and Sri Lanka, and indicate that populations, while generally small and isolated, are widespread. Sri Lanka has the largest remaining wild populations (approx. 2,000 individuals), but they are concentrated in only two National Parks, Wilpattu and Yala (Whitaker and Whitaker 1979). In other areas, muggers are being threatened by rapid agricultural and industrial development (Whitaker and Whitaker 1989). In India, muggers are reported from over 50 locations and the wild population is tentatively estimated at 3,000–5,000 (Anon. 1993b). In Pakistan, the mugger is reported to be extinct in the Punjab province due to alteration of habitat (Chaudhury 1993). Small populations are reported in Sind along the Nara Canal, in Khairpur Sanghar and Nawab districts and Haleji lake. These are said to be vulnerable and diminishing. The mugger remains widely distributed in Baluchistan with confirmed locations on the Nari, Hab, Titiani, Hingol and Dasht rivers and Nahang and Kach Kuar. In all cases the populations are of unknown but small size. Approximately 50 individuals are held in captivity in seven facilities and three pairs are breeding. A program is ongoing to obtain mugger from the captive bred stock in India for release into protected habitats. A survey in Nepal was initiated in 1993 (McEachern 1994). Preliminary results indicate that the mugger is now restricted to isolated populations, primarily in protected habitats. Small numbers of individuals are known or suspected from the Mahakali, Nala, Karnali, Babai, Rapti, Narayani and Koshi river systems. Alienation of habitat by river disruption and damming, and mortality in fisheries are major problems. A recent investigation in Bangladesh (Cox and Rahman 1994) reports the mugger to be extinct in the wild and only six wild derived specimens are kept in captivity. In Iran, muggers are known from the drainages of the Sarbaz (=Dashtiari) and Kajou (=Koja) rivers. Preliminary counts of the main habitat in 1992 revealed at least 118 individuals (Gholi Kami 1994, Gholi Kami and Saghari 1993). Van Dink (1993), reports that the last record of muggers in Myanmar was 1867–68 and that the species is probably extinct there.

Management of mugger crocodiles is based principally on the legal protection of wild populations and captive breeding for restocking. In India, a large-scale captive rearing program was initiated in 1975. The project has collected eggs from the wild, as well as produced young from captive adult breeding stock. The resulting juveniles have been used to restock natural populations in 28 national parks, wildlife reserves and crocodile sanctuaries throughout the country. A total of 1,193 individuals were released between 1978 and 1992. Unfortunately, there has been little improvement in persuading people to live with crocodiles and there is little additional habitat where more muggers can be introduced. Currently there are over 12,000 muggers in captivity. Facing a crisis of overcrowding, the Indian government instructed breeding centers to cease producing new offspring in 1994 and the program is currently at a standstill.

The Indian government has adopted a policy prohibiting any evaluation of commercial use of captive bred crocodiles for conservation. The future of the mugger in India is therefore uncertain.

Priority projects

High priority

Determination of the status of restocked muggers in India: No single agency is responsible for tracking the success of restocking activities. The current crisis of overstocking in captive breeding centers and uncertainty on the success of restocking remains an impediment to developing a coherent new strategy to meet current needs. Ongoing studies on survival, growth and population size at restocked locations are needed.

Establishment of a conservation / management program in Pakistan: Recent reports suggest that mugger crocodile populations in Pakistan remain viable after being severely depleted by commercial hunting. However, no formal surveys have been conducted, and in some parts of the country continued killing has been reported. Interest has been expressed in initiating a restocking program similar to the one in India. However, surveys of population status and a biological research program are a prerequisite to establishing a management program.

Conservation and management in Sri Lanka: Since the surveys by Whitaker and Whitaker (1979) no work has been done in Sri Lanka, which at that time had the best remaining wild mugger populations. New surveys are required to reassess the current status of the species, and are needed as a prerequisite to developing a conservation program.

Moderate priority

Expansion of restocking program in India: Restocking efforts have declined in recent years, in part due to a lack of suitable release sites. This has been attributed to the lack of field investigations and positive public-relations programs (Whitaker and Whitaker 1989). In some areas local opposition to crocodile releases has blocked restocking proposals. New areas appropriate for crocodile releases need to be identified and included in the crocodile reserve system. Appropriate public relations efforts also need to be undertaken to ameliorate local opposition based on misinformation concerning crocodiles.

Potential for sustainable management in India: The surplus of captive animals and recent human-crocodile conflicts have made the sustainable utilization (ranching or farming) of this species a potential alternative management strategy. The feasibility of limited commercial utilization needs to be examined as a means to invigorate the Indian crocodile conservation program.

Captive-bred muggers, Crocodylus palustris, at Madras
Crocodile Bank, India. Shortage of locations for wild release
is causing crowding in captive rearing facilities. Photo by
H. Andrews.