Using environmental niche modelling to investigate the importance of ambient temperature in human-crocodilian attack occurrence for two species of crocodilian

Crocodilians are responsible for more attacks on people than any other large predator, which has important implications for human safety and crocodilian conservation. Understanding the drivers of crocodilian attacks on people could help minimise future attacks and inform conflict management. Crocodilian attacks follow a seasonal pattern for many species; however, there has been limited analyses of the relationship between fine-scale contemporaneous environmental conditions and atack occurrence. Here, we use methods from environmental niche modelling to explore the relationships between abiotic predictors and human attack occurrence at a daily temporal resolution for two species: the Nile crocodile (Crocodylus niloticus) in South Africa and Swaziland (renamed Eswatini), and the American alligator (Alligator mississippiensis) in Florida. Our results indicate that ambient daily temperature in the most important abiotic temporal predictor of attack occurrence for both species, with attack likelihood increasing sharply at temperatures above 18°C and peaking at 28°C. It is likely that this relationship is explained partially by human propensity to spend time in and around water in warmer weather, but also by the effect of temperature on crocodilian hunting behaviour and physiology, especially the ability to digest food. We discuss the potential of our findings to contribute to the management of crocodilians, with benefits for human safety and conservation, as well as the application of environmental niche modelling to analysing human conflict with other species, including ectotherms and endotherms.

[1]  Stephen E. Fick,et al.  WorldClim 2: new 1‐km spatial resolution climate surfaces for global land areas , 2017 .

[2]  C. Gienger,et al.  Patterns of human–crocodile conflict in Queensland: a review of historical estuarine crocodile (Crocodylus porosus) management , 2017, Wildlife Research.

[3]  Rabindranath Jana,et al.  Human–crocodile conflict in the Indian Sundarban: an analysis of spatio-temporal incidences in relation to people's livelihood , 2017, Oryx.

[4]  S. Creel,et al.  Hunting on a hot day: effects of temperature on interactions between African wild dogs and their prey. , 2016, Ecology.

[5]  M. Waltert,et al.  Assessing the Role of Livestock in Big Cat Prey Choice Using Spatiotemporal Availability Patterns , 2016, PloS one.

[6]  Jennifer R. B. Miller Mapping attack hotspots to mitigate human–carnivore conflict: approaches and applications of spatial predation risk modeling , 2015, Biodiversity and Conservation.

[7]  R. Morato,et al.  Modeling the risk of livestock depredation by jaguar along the Transamazon highway, Brazil , 2015 .

[8]  Mushtaq Ahmed,et al.  Food consumption of saltwater crocodile (Crocodylus Porosus) in a reptile farm of Bangladesh , 2015 .

[9]  S. Pooley,et al.  Using predator attack data to save lives, human and crocodilian , 2015, Oryx.

[10]  O. Monroy-Vilchis,et al.  Spatial model of livestock predation by jaguar and puma in Mexico: Conservation planning , 2013 .

[11]  A. Wood Territories and Urbanisation in South Africa: Atlas and geo-historical information system (Dysturb) , 2012 .

[12]  L. Guillette,et al.  Seasonal Androgen Cycles in Adult Male American Alligators (Alligator mississippiensis) from a Barrier Island Population1 , 2011, Biology of reproduction.

[13]  J. van der Ploeg,et al.  ‘Why must we protect crocodiles?’ Explaining the value of the Philippine crocodile to rural communities , 2011 .

[14]  P. Jha,et al.  Snakebite Mortality in India: A Nationally Representative Mortality Survey , 2011, PLoS neglected tropical diseases.

[15]  T. Coulson,et al.  Living with predators: a focus on the issues of human–crocodile conflict within the lower Zambezi valley , 2011 .

[16]  J. Ragle,et al.  IUCN Red List of Threatened Species , 2010 .

[17]  A. Milton,et al.  Annual Incidence of Snake Bite in Rural Bangladesh , 2010, PLoS neglected tropical diseases.

[18]  F. Urbano,et al.  Human–wildlife conflict in Mozambique: a national perspective, with emphasis on wildlife attacks on humans , 2010, Oryx.

[19]  F. Lamarque,et al.  Human-wildlife conflict in Africa: causes, consequences and management strategies. , 2009 .

[20]  A. Townsend Peterson,et al.  Novel methods improve prediction of species' distributions from occurrence data , 2006 .

[21]  C. Franklin,et al.  Physiological mechanisms of thermoregulation in reptiles: a review , 2005, Journal of Comparative Physiology B.

[22]  V. Lance Alligator physiology and life history: the importance of temperature , 2003, Experimental Gerontology.

[23]  Tobias Wang,et al.  Effects of temperature on the metabolic response to feeding in Python molurus. , 2002, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[24]  T. Gleeson,et al.  Temperature Effects on Aerobic Metabolism and Terrestrial Locomotion in American Alligators , 1997 .

[25]  C. Kofron The reproductive cycle of the Nile crocodile (Crocodylus nilotkus) , 1990 .

[26]  J. Hutton Growth and feeding ecology of the nile crocodile Crocodylus niloticus at Ngezi, Zimbabwe , 1987 .

[27]  T. D. Coulson,et al.  Effect of temperature on the rates of digestion, amino acid absorption and assimilation in the alligator , 1986 .