Last summer I traveled to Cowra, New South Wales, to assist PhD student Stephanie Pulsford with her fieldwork. Stephanie’s work involves studying the movement of reptiles, amphibians and invertebrates across Box-Gum Grassy Woodlands.
When we chop down trees and clear vegetation to make way for roads and farms, we are destroying the habitats of local species. As human populations grow around the world, so too does this problem. The destruction causes habitat fragmentation, which isolates smaller populations of terrestrial species. Without the cover of vegetation, individuals are at a higher risk of predation. By separating populations there is an increased probability of inbreeding, restricting gene flow and weakening the individuals.
Stephanie seeks to find a realistic and cost-effective way to improve the connectivity and movement of lizard and amphibian populations across farmlands. She is researching different scenarios, using fences vs logs vs neither, to see which situation allows for better movement of the individuals. She hopes that this will allow farmers to make changes to their property, which favour the movement of reptile and amphibian populations.
I spent one week with Stephanie, where we lived with other volunteers in a cottage located on one of the farms we were working on. The first few days were spent setting up the traps, a laborious task of digging trenches and hammering in the frames for the drift fences. We set up funnel and pitfall traps to catch any animals which ran along the fences. After that, every day began at about 6am as it was the height of summer and animals could not be left in the traps for too long or they would dry out. Initially, I was a bit apprehensive sticking my hand into a pitfall trap full of huntsman spiders, centipedes, and on one occasion, a Blackish Brown snake. Nevertheless, I got used to it, and every day we recorded what we found.
The most common species of frog we caught was the Spotted Marsh Frog, and lizard was the Rainbow Skink. When individuals were captured, we injected them with a small drop of an illuminous substance which hardens under the skin. This is deemed safe for the animal, and is injected on their underside so as not to make them more visible to predators. In the case of recapture of the same individual, we knew that it has been caught before by shining UV light on the marking. This capture recapture method provides an important insight into the movement of the species across the landscape.
The Bigger Picture
Stephanie is gathering the data from her fieldwork to determine which areas have more amphibian and reptile movement. She will compare the exposed areas with the sheltered areas that have logs, and with the areas which have fences. If animals use the sheltered areas more often when moving locations, by placing logs or fences on their farms landowners could improve the quality of life for these species. Best of luck to Stephanie with her PhD!
Fischer, Joern, David B. Lindenmayer, and Ann Cowling. “The challenge of managing multiple species at multiple scales: reptiles in an Australian grazing landscape.” Journal of Applied Ecology 41.1 (2004): 32-44.
Hazell, Donna, et al. “A comparison of constructed and natural habitat for frog conservation in an Australian agricultural landscape.” Biological Conservation119.1 (2004): 61-71.
Mac Nally, Ralph, and Geoff W. Brown. “Reptiles and habitat fragmentation in the box-ironbark forests of central Victoria, Australia: predictions, compositional change and faunal nestedness.” Oecologia 128.1 (2001): 116-125.