Abstract
Human-wildlife conflict occurs when human requirements encroach on those of wildlife populations, with potential costs to both humans and wild animals. As top predators in most inland waters, crocodilians are involved in human-wildlife conflicts in many countries. Here we present findings of a 5-year survey on human-crocodile conflict on the island of Sri Lanka and relate the results to improving management practices. We aimed to quantify and understand the causes of human-crocodile conflict in Sri Lanka, and propose solutions to mitigate it. Visual encounter surveys were carried out to estimate the population size of Saltwater Crocodiles. We recorded 778 sightings of Saltwater Crocodiles at 262 of 400 locations surveyed, and estimate the total population to comprise more than 2000 non-hatchlings and to have increased at an average rate of 5% p.a. since 1978. We propose four crocodile vigilance zones within the wet zone and one crocodile vigilance zone within the dry zone of the country. Specific threats to Saltwater Crocodiles identified in crocodile vigilance zones were: habitat destruction and loss; illegal killing and harvesting (17 killings out of fear, ~200 incidents of killing for meat and skins, ~800 eggs annually for consumption); unplanned translocations; and, interaction with urbanization (10 incidents of crocodiles being run over by trains/vehicles and electrocution). Additionally, 33 cases of crocodile attacks on humans were recorded [8 fatal, 25 non-fatal (minor to grievous injuries)] and more than 50 incidents of attacks on farm and pet animals.
Highlights
Human-wildlife conflict is a growing issue worldwide (Woodroffe et al 2005) and crocodilians are one of the major groups involved (Lamarque et al 2009)
Two allopatric species of crocodiles occur in Sri Lanka; the Mugger Crocodile, Crocodylus palustris Lesson, 1831, and the Saltwater or Estuarine Crocodile, Crocodylus porosus Schneider, 1801 (Deraniyagala 1939)
On the zones of high human-crocodile conflict (HCC) incidence involving Saltwater basis of the survey and interview results we identified Crocodiles within the survey regions, which we refer to as “Crocodile Vigilance Zones” (CVZ): RHW - RagamaHendala-Wattala; MDW - Moratuwa-DehiwalaWellawatta; BBA - Beruwala-Bentota-Ambalangoda; MMA - Matara-Malimbada-Akuressa
Summary
Human-wildlife conflict is a growing issue worldwide (Woodroffe et al 2005) and crocodilians are one of the major groups involved (Lamarque et al 2009). The Saltwater Crocodile is the largest living reptile on Earth; it can grow up to 6–7 m (Webb et al 1978; Whitaker & Whitaker 2008; Erickson et al 2012). Like other crocodilians it is an opportunistic feeder, using active hunting or ‘sit and wait’ strategies (Cooper & Jenkins 1993), and the frequency of different prey items varies significantly with habitat and body size (Taylor 1979; Webb & Manolis 1989). Telemetry studies are increasing our knowledge of movement patterns and extent of home ranges for Saltwater Crocodiles (e.g., Webb & Messel 1978; Kay 2004; Read et al 2007; Brien et al 2008; Campbell et al 2013, 2014; Hanson et al 2014), which can assist management efforts, there is still a paucity of information for most range states for the species, including Sri Lanka
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