by Ifham Nizam
All countries in the region are gearing up for the World Crocodile Conference, where the Crocodile Specialist Group’s 22nd Working Meeting will be held in Sri Lanka in May next year—with head counts of the three main species.
Leading herpetologist Anslem de Silva says that head counts of the species in Sri Lanka will be done with the support of the Department of Wildlife, university professors and animal enthusiasts.
De Silva yesterday informed all members of the Crocodile Species Group (CSG) and non-members currently working on the matter that activities of the World Crocodile Conference (WCC) are progressing well and they were getting a good response from many countries.
“As hosting the WCC is an achievement for CSG South Asia and Iran, we have to take an active part by participating and presenting papers at the various symposia and workshops that will be held during the WCC session here,’ he said.
Following the successful session held at the 21st Working Meeting in Manila last year, De Silva proposed to convene a session on the endangered species—the Red List Assessment of South Asia and Iran Crocodiles—at the next working meeting of the group in Colombo, 2013.
Endangered species assessment
“I am happy to say that I personally discussed with Dr. James Perran Ross of the Department of Wildlife Ecology and Conservation, University of Florida, who is the CSG Red List Authority, to help us to organize IUCN (International Union for the Conservation of Nature) Red List Assessments for three of our crocodile species. During the last CSG working meeting in Manila, Perran effectively accomplished this task within two hours with a couple of background presentations and four short reports of ‘case studies’ to demonstrate the process.”
He appreciated Ross’s support and participation to accomplish this task and has requested him to prepare information prior to the meeting.
The proposed structure of the demonstration process includes an introduction to the red list assessment and criteria used, definitions and terms, nature of the criteria, CSG assessment process, global and regional assessments, guidelines and resources, presentations of case studies and recent and pending crocodilian red list assessments.
Field data on day and night eye shine counts will be taken to do global and regional assessments of the mugger (‘Crocodylus palustris’) in Sri Lanka, India, Iran, and Nepal. The saltwater crocodile (‘Crocodylus porosus’) will be regionally assessed in the Indian subcontinent and Sri Lanka, while there will be a review of the current assessment of the gharial (‘Gavialis gangeticus’).
The IUCN Red List is the authoritative list of globally threatened animals and plants, now on-line, fully searchable and listing more than 35,000 animals. The Red List has always been generated by species experts of the Species Survival Commission specialist groups like CSG. CSG used new criteria to assign Red List categories to all 23 crocodilians in 2002 and has re-evaluated several species since then, notably the Gharial and Cuban crocodile.
However, most CSG crocodilian assessments are unchanged and largely unexamined since the mid-1990s and are overdue for updates. From early, fairly informal beginnings in 1972, the list and the process that produces it has steadily become more objective, scientific and (unavoidably) more complex.
Red List categories and criteria are now based on IUCN Red List categories and criteria Version 3.1 (2001). Species are assigned to one of seven categories if, and only if, they meet just one of the criteria applying to any category. Three of the categories are in the familiar ‘threatened’ status (Vulnerable, Endangered and Critically Endangered). The other categories accommodate species that are not threatened (Least concern, Near Threatened, Extinct in the wild and Extinct). The criteria for threatened species cover five broad indices of extinction risk: reduction in population size, limited geographic range, small population size combined with other risk factors (decline, population structure), extremely small population size and quantitative analysis indicating risk of extinction.
Each criterion has detailed components and sub-criteria and objectives with quantitative thresholds. The terminology for Red List criteria is specific to this use and carefully defined. There are rules and ‘Guidelines’ for applying the criteria and a large body of case history and precedent to guide their application. The Red List only considers all of a species throughout its global range, but there are additional criteria to adjust assessments of local or regional populations.
All red list assessments are now entered and processed through IUCN’s Species Information System (SIS)—an automated on-line database for red list assessment. These components are all fully described in the red list materials and guidelines.
To apply these criteria to a species, an ‘assessment’ is performed. This is usually done by specialist groups or by specially convened ‘Global Biodiversity Assessment Workshops.’ Assessments undergo a procedure of drafting, review and evaluation, checking by IUCN red list staff and then publication on a roughly annual schedule (Assessments completed by August of one year are published by May the following year). Each specialist group (including CSG) has established a ‘Red List Authority’ (RLA) under the guidance of an RLA focal point to coordinate, review and submit its assessments.
For CSG, the final authority for red listing crocodiles lies with the CSG chairman operating with the steering committee. The chairman has designated Perran Ross to be the RLA focal point and coordinate our internal process. Perran, in consultation with the Chair and steering committee, proposes small groups of ‘assessors’ who generate the raw material of each species assessment.
Each assessment is then independently reviewed by between two and three experts additional to the assessors. The reviewed assessments will then be approved by the chair and passed to SSC red list staff. They will perform their own review—largely to ensure correct application and interpretation of the criteria—and upon approval, pass the assessment into the publication stream.
CSG has just completed and published on-line revised ‘Action Plan’ sheets for each crocodilian species and these summarize the most current information, threats and situational review. These 2010 action plan sheets will be the basis for the next round of crocodilian red list assessments and their authors will be invited to be in the core group of ‘assessors’ for each species.
Anslem De Silva says, historically, Sri Lanka had a large population of mugger crocodiles, but at the height of the leather industry in the 1920-30s, the species had been extensively hunted to the point of near extinction. “Nevertheless, since legal protection was introduced in 1938, appreciable populations have established, especially within larger tanks (reservoirs) in the dry zone. With the exponential increase of human populations in the dry zone due to large-scale agricultural projects, the number of humans and livestock using these water bodies has also largely increased in the recent past,” he added.
This sharing of an essential but limited resource has resulted in an increase in the human-crocodile conflict. A preliminary survey conducted in 2010 in more than 100 water bodies reveals that about 130 persons were attacked with 35 fatalities. About 80 per cent of them were attacked while they were bathing and washing clothes in tanks. Conversely, over 50 crocodiles were killed in revenge and as a measure to prevent future attacks.
Crocodile Excluding Enclosures (CEE) has been traditionally used by people in the southern wet-zone, where humans frequently use rivers inhabited by saltwater crocodiles.
According to De Silva, the CEE is a simple device where three sides are fenced with wooden poles. Given the success of these enclosures in segregating humans and crocodiles, they could be modified and introduced to the tanks in the northern dry-zone.
De Silva said, “We plan to establish a set of experimental CEEs to monitor their benefits and educate the local residents on their use. This could be a simple but effective way of saving lives of humans and livestock and reducing the human-induced mortality of muggers in Sri Lanka.”
At present, the largest wild mugger population in the world is found here. However, they are facing numerous threats, making the existing populations vulnerable to future depletion.
De Silva believes segregating humans and muggers would be the best solution for this emerging concern. This could be achieved by introducing a traditional system of CEEs inside which residents could safely perform their daily needs. The proposed study will help. Installation of CEEs with the involvement of the vulnerable local people; introducing a system to monitor and maintain the setup, and increase awareness on the importance of the crocodiles and preventing their attacks.
An earlier study by De Silva in 2008 has shown that in the Nilwala ‘ganga’ and its tributaries in Southern Sri Lanka had a high incidence of saltwater crocodile attacks. However, all crocodile attacks were on people, who did not use the traditional CEEs.
Also known as marsh or swamp crocodile, it is not endemic.
Scientific name: Crocodylus palustris (Lesson, 1831)
Sinhala name: ‘Hela Kimbula.’
Range: Iran, India, Nepal, Pakistan, Sri Lanka, Bangladesh (maybe extinct in the wild), Bhutan (maybe extinct), Myanmar (is probably extinct).
Conservation Overview: Availability of survey data on muggers is poor. The need for recovery of its wild population is high. The potential for its sustainable management is moderate.
IUCN red list data of 2009 shows a decline of 20 per cent in three generations of the species in the extent of its occurrence. Its wild population is less than 2,500 adults while its habitat is fragmented and declining. The species count was last assessed in 1996. Principal threats to the mugger are its habitat destruction, fragmentation, and transformation, whiles its mortality is mainly
due to increased fishing activities.
Ecology and Natural History
The Mugger is a medium-sized crocodile, maximum length at four to five metres, and has the broadest snout of any living member of the genus ‘Crocodylus.’ It is principally restricted to the Indian subcontinent, where it may be found in a number of freshwater habitat types including rivers, lakes, tanks, irrigation canals and man-made ponds and agro wells. The mugger can even be found in coastal saltwater lagoons and estuaries.
The mugger is a hole-nesting species, with egg-laying taking place during the annual dry season. Females become sexually mature at approximately 1.8-2 metres, and lay 10-30 eggs. Nests are located in a wide variety of habitats, and females have even been known to nest at the opening of, or inside, their burrow. Incubation is relatively short, typically lasting 55-75 days.
It is known to dig burrows and a detailed study of mugger burrows has been conducted by De Silva. Some burrows are 10-15 metres long. Muggers live a communal life and one can see even up to 200-300 muggers in one tank.
Saltwater or Estuarine Crocodile
This is a man-eating crocodile and is not endemic. It’s mainly a solitary species—and have their own territories, especially males. A saltwater croc can grow up to six to seven meters in length and some can be dangerous to man.
Sinhala name: ‘Gata Kimbula’ or ‘Minikana Kimbula’
Tamil name: Semmukku Muthalei (copper colour crocodile)
Genus: Crocodylus (Gronovius (1763), Laurenti (1768))
Scientific name: Crocodylus porosus (Schneider, 1801)
Ecology and Natural History
The saltwater crocodile is a mound nest builder—the female builds a mound nest with dead leaves and other debris and mud—approximately 2.5 feet tall and 3 feet wide and lays 10-50 eggs inside it. Courtesy: Ceylon Today