title: Home range utilisation and long-range movement of estuarine crocodiles during the breeding and nesting season.
abstract: The estuarine crocodile (Crocodylus porosus) is the apex-predator in waterways and coastlines throughout south-east Asia and Australasia. C. porosus pose a potential risk to humans, and management strategies are implemented to control their movement and distribution. Here we used GPS-based telemetry to accurately record geographical location of adult C. porosus during the breeding and nesting season. The purpose of the study was to assess how C. porosus movement and distribution may be influenced by localised social conditions. During breeding, the females (2.92 ± 0.013 metres total length (TL), mean ± S.E., n = 4) occupied an area<1 km length of river, but to nest they travelled up to 54 km away from the breeding area. All tagged male C. porosus sustained high rates of movement (6.49 ± 0.9 km d(-1); n = 8) during the breeding and nesting period. The orientation of the daily movements differed between individuals revealing two discontinuous behavioural strategies. Five tagged male C. porosus (4.17 ± 0.14 m TL) exhibited a 'site-fidelic' strategy and moved within well-defined zones around the female home range areas. In contrast, three males (3.81 ± 0.08 m TL) exhibited 'nomadic' behaviour where they travelled continually throughout hundreds of kilometres of waterway. We argue that the 'site-fidelic' males patrolled territories around the female home ranges to maximise reproductive success, whilst the 'nomadic' males were subordinate animals that were forced to range over a far greater area in search of unguarded females. We conclude that C. porosus are highly mobile animals existing within a complex social system, and mate/con-specific interactions are likely to have a profound effect upon population density and distribution, and an individual's travel potential. We recommend that impacts on socio-spatial behaviour are considered prior to the implementation of management interventions.
authors: The School of Biological Sciences, The University of Queensland, Brisbane, Australia. hamish.campbell@uq.edu.au
authors: Hamish A
authors: HA
authors: Campbell
authors: Ross G
authors: RG
authors: Dwyer
authors: Terri R
authors: TR
authors: Irwin
authors: Craig E
authors: CE
authors: Franklin
mesh_terms: D000489:Alligators and Crocodiles / Q000502:physiology*; D063147:Animal Distribution; D000818:Animals; D001315:Australia; D001947:Breeding; D005260:Female; D040362:Geographic Information Systems; D006702:Homing Behavior; D008297:Male; D045483:Rivers; D012621:Seasons
references: Comp Immunol Microbiol Infect Dis. 1982;5(1-3):247-56
references: 7128079
references: PLoS One. 2007 Sep 26;2(9):e949
references: 17895990
references: Science. 1977 Jul 15;197(4300):215-23
references: 327542
references: Science. 2001 Nov 30;294(5548):1923-6
references: 11729317
references: Trends Ecol Evol. 1996 Feb;11(2):92-8
references: 21237769
references: Am Nat. 1997 Jul;150(1):98-121
references: 18811277
references: Nature. 2006 Jul 20;442(7100):265-9
references: 16855582
references: Ecol Lett. 2005 May;8(5):513-23
references: 21352455
references: J Anim Ecol. 2010 Sep;79(5):955-64
references: 20546063
references: Proc Biol Sci. 2007 Nov 7;274(1626):2769-77
references: 17725974
references: J Anim Ecol. 2011 Jul;80(4):786-98
references: 21418209