Department of Environment and Natural Resources
Groundbreakingresearch has found the Cobourg Peninsula strongly influences the movement anddispersal of saltwater crocodiles (Crocodylusporosus) in the Top End.
Leadresearcher and Department of Environment and Natural Resources (DENR) wildlifescientist, Mr Yusuke Fukuda, said the findings now available in the sciencejournal PLOS ONE https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0205862- provide newinsights into C. porosus movements,which might have management significance for public safety.
Translocatedsalties often return to their original capture sites, which complicatesmanagement interventions aimed at reducing human-crocodile conflict, Mr Fukudasaid.
Weexamined the spatial events implicated in this homing ability, using satellitetracking devices on eight salties of different ages and sizes.
Fivemales (3.03m to 4.02m) were shifted and released 100-300 kilometres from theircapture sites and three others (3.67m to 4.23m) were released at their site ofcapture as controls.
Thetranslocated salties were highly mobile relative to the controls, and moved atsea in the direction of their original capture site.
However,they were unable or unwilling to swim around a geographic structure, CobourgPeninsula, which prevented homing being achieved in all five cases.
Thisis in contrast to what happens in Queensland, where Cape York is not aneffective barrier to crocodile movement, at least for the larger salties.
Geneticanalysis of tissue samples from nests across the NT coast also demonstratedsignificant genetic diversity across the coast, and confirmed that CobourgPeninsula is a barrier separating genetic stocks across the NT coast.
Thissuggests that more than 250 crocodiles the NT Government removes each year fromthe Darwin Harbour for public safety come from the western side of thePeninsula.
Thesatellite tracking of crocodiles as part of Mr Fukudas study was funded andsupported by the Northern Territory Government, Australian Government, CharlesDarwin University, Wildlife Management International Pty Ltd and The AustralianNational University (ANU).
Thegenetic analyses presented in Mr Fukudas study were funded and supported bythe Northern Territory Government, ANU, National Geographic Society, HolsworthWildlife Research Endowment, IUCN-SSC Crocodile Specialist Group StudentResearch Assistance Scheme, ACT Herpetological Association and the NorthernTerritory Crocodile Farmers Association.
