Critically evaluating best management practices for preventing freshwater turtle extinctions.
Ex situ conservation tools, such as captive breeding for reintroduction, are considered a last resort to recover threatened or endangered species, but they may also help reduce anthropogenic threats where it is difficult or impossible to address them directly. Headstarting, or captive rearing of eggs or neonate animals for subsequent release into the wild, is controversial because it treats only a symptom of a larger conservation problem; however, it may provide a mechanism to address multiple threats, particularly near population centers. We conducted a population viability analysis of Australia's most widespread freshwater turtle, Chelodina longicollis, to determine the effect of adult roadkill (death by collision with motor vehicles), which is increasing, and reduced recruitment through nest predation from introduced European red foxes (Vulpes vulpes). We also modeled management scenarios to test the effectiveness of headstarting, fox management, and measures to reduce mortality on roads. Only scenarios with headstarting from source populations eliminated all risks of extinction and allowed population growth. Small increases in adult mortality (2%) had the greatest effect on population growth and extinction risk. Where threats simultaneously affected other life-history stages (e.g., recruitment), eliminating harvest pressures on adult females alone did not eliminate the risk of population extinction. In our models, one source population could supply enough hatchlings annually to supplement 25 other similar-sized populations such that extinction was avoided. Based on our results, we believe headstarting should be a primary tool for managing freshwater turtles for which threats affect multiple life-history stages. We advocate the creation of source populations for managing freshwater turtles that are greatly threatened at multiple life-history stages, such as depredation of eggs by invasive species and adult mortality via roadkill.
School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Building M15, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
R-J
0000-0001-8112-4221
RJ
Spencer
School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Building M15, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
J U
JU
Van Dyke
School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), Sydney, NSW 2006, Australia.
Michael B
MB
Thompson
D000818:Animals; D001315:Australia; D003247:Conservation of Natural Resources / Q000379:methods*; D053476:Extinction, Biological; D020387:Food Chain; D005589:Foxes / Q000502:physiology*; D005618:Fresh Water; D058865:Introduced Species; D008136:Longevity; D009517:New South Wales; D011156:Population Density; D011157:Population Dynamics; D011235:Predatory Behavior; D012306:Risk; D014426:Turtles / Q000502:physiology*; D014739:Victoria
Australia; Chelodina longicollis; conservación ex situ; depredadores invasores; ex situ conservation; foxes; harvest populations; headstarting; inicio con ventaja; invasive predators; mortalidad en carreteras; poblaciones de cosecha; road mortality; zorros