A shocking result—Electric fences protect western saw‐shelled turtle (Myuchelys bellii) nests from depredation by foxes

Abstract

Introduced red foxes (Vulpes vulpes) are a major predator of freshwater turtle nests in Australia. We evaluated the effectiveness of electric fences, in combination with individual nest protection, for shielding western saw‐shelled turtle (Myuchelys bellii: Chelidae) nests from predation by foxes. We compared the numbers of raided and intact turtle nests found in paired fenced treatment and unfenced control areas of streambank. We also individually protected all intact nests found in both area types with wire mesh or a steel cage. The total numbers of nests found in treatment and control areas did not significantly differ from parity, but significantly more intact nests were found in treatment areas and significantly more raided nests in control areas. The fences were occasionally damaged by livestock, wildlife and flooding, rendering them inoperative for varying periods of time until repair. However, foxes raided nests inside the fences on only two occasions, despite these breaks in functionality. Our study demonstrates that electric fences can provide an effective method of protecting entire nesting areas from depredation by foxes.

Juvenile proportion as a predictor of freshwater turtle population change

“…The population in the Namoi River system may be at risk due to the scarcity of juveniles, although we did not detect a trend of increasing average SCL. Its low proportion of juveniles may be related to locally intense nest and hatchling predation (Streeting et al, 2023) or possibly reduced juvenile survival as a result of intraspecific competition, which has been suggested for other turtle populations (Fordham et al, 2009;Noda & Ohkawara, 2018). The population in the Deepwater River may also be of some concern, even though it did not show an ageing trend, because it is exposed to potential competition from Emydura macquarii (Chessman, 2015(Chessman, , 2021.…”

“…A 10‐year multi‐agency conservation programme (‘Turtles Forever: Securing Australia's Wild Populations of Bell's Turtle’) began in mid‐2016 with the aim of securing all NSW populations through a range of turtle research and conservation activities, together with community engagement and education. On‐ground actions funded by this programme include permanent riparian fencing to exclude livestock from potential nesting areas, temporary electric fencing to deter foxes from entering nesting areas during the annual period of nesting and egg incubation, broad‐scale fox control, protection of nests with wire mesh and cages, and ex situ incubation of eggs obtained by hormonal induction of oviposition by gravid females, with subsequent release of hatchlings and head‐started juveniles (Streeting et al, 2021, 2022, 2023).…”

“…However, published information on the actual impact of these threats is scant. Rates of nest predation by V. vulpes are known to be high, and predation on nesting females has also been detected (Streeting et al, 2023). Although eye abnormalities are frequent in some locations, they do not appear to impair body condition or preclude long-term survival (Chessman, 2015).…”

Opportunities for research and conservation of freshwater turtles in Australia

“…Conservation biologists continue to refine the best approaches to counteract population declines and causes of mortality in Australian freshwater turtles. Actions include attempts to mitigate threats of feral species such as pigs and foxes through predator‐proof fencing (Cochrane, 2006; Streeting et al, 2023), nest protection measures (Campbell et al, 2020; Connell, 2018;Streeting et al, 2023; Terry et al, 2023), and artificial incubation of eggs and release of hatchlings (Streeting et al, 2022). Likewise, conservation translocations of Critically Endangered species such as reintroductions ( Myuchelys georgesi ) and assisted colonization ( Pseudemydura umbrina ) have attempted to mitigate critically low population sizes due to disease (Chessman et al, 2020) and habitat loss and degradation (Bouma et al, 2020; Kuchling et al, 2018).…”

“…To address declines in Australian freshwater turtles and ensure their persistence for future generations, research (Chessman, Dillon, et al, 2023; Chessman, Fielder, et al, 2023; Coleman, 2023; Kidman et al, 2023; McKnight, 2023; McKnight et al, This issue; Nordberg & McKnight, 2023; Van Dyke et al, This issue) and conservation actions (Campbell et al, 2023; Streeting et al, 2023; Terry et al, 2023) are ongoing. However, compared to many other taxa, freshwater turtles have received less focus and funding in Australia (Gawne et al, 2020).…”