In the wet-dry tropics, animal species face the major challenges of acquiring food, water or shelter during an extended dry season. Although large and conspicuous animals such as ungulates and waterfowl migrate to wetter areas during this time, little is known of how smaller and more cryptic animal species with less mobility meet these challenges. We fenced off the entire entrance of a gorge in the Australian tropical savanna, offering the unique opportunity to determine the composition and seasonal movement patterns of the small vertebrate community. The 1.7 km-long fence was converted to a trapline that was deployed for 18-21 days during the early dry season in each of two years, and paired traps on both sides of the fence allowed us to detect the direction of animal movements. We predicted that semi-aquatic species (e.g., frogs and turtles) would move upstream into the wetter gorge during the dry season, while more terrestrial species (e.g., lizards, snakes, mammals) would not. The trapline captured 1590 individual vertebrates comprising 60 species. There was a significant bias for captures on the outside of the fence compared to the inside for all species combined (outside/inside = 5.2, CI = 3.7-7.2), for all vertebrate classes, and for specific taxonomic groups. The opposite bias (inside/outside = 7.3, N= 25) for turtles during the early wet season suggested return migration heading into the wet season. Our study revealed that the small vertebrate community uses the gorge as a dry season refuge. The generality of this unreplicated finding could be tested by extending this type of survey to tropical savannahs worldwide. A better understanding of how small animals use the landscape is needed to reveal the size of buffer zones around wetlands required to protect both semi-aquatic and terrestrial fauna in gorges in tropical savannah woodland, and thus in ecosystems in general.
Department of Ecology & Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, United States of America;School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia;School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia;Fenner School of Environment and Society, Australian National University, Canberra, Australian Capital Territory, Australia;Department of Natural Sciences, Daemen College, Amherst, New York, United States of America;Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia;Queensland Museum, South Brisbane, Queensland, Australia;Department of Terrestrial Zoology, Western Australian Museum, Welshpool, Western Australia, Australia;Utah’s Hogle Zoo, Salt Lake City, Utah, United States of America;Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia;Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia;Stop the Toad Foundation, West Perth, Australia;Frogwatch NT, Wagaman, Northern Territory, Australia;El Questro Wilderness Park, Kununurra Western Australia, Australia
Recommended Citation:
J. Sean Doody,Simon Clulow,Geoff Kay,et al. The Dry Season Shuffle: Gorges Provide Refugia for Animal Communities in Tropical Savannah Ecosystems[J]. PLOS ONE,2015-01-01,10(7)