Study

Experimental analysis of the impact of foxes on freshwater turtle populations

  • Published source details Spencer R.J. & Thompson M.B. (2005) Experimental analysis of the impact of foxes on freshwater turtle populations. Conservation Biology, 19, 845-854.

Actions

This study is summarised as evidence for the following.

Action Category

Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing

Action Link
Reptile Conservation

Remove or control predators using lethal controls: Tortoises, terrapins, side-necked & softshell turtles

Action Link
Reptile Conservation
  1. Release reptiles born/hatched in captivity from wild-collected eggs/wild-caught females without rearing

    A replicated study in 1996–2000 in two lagoons in south-eastern Australia (Spencer & Thompson 2005) found that releasing captive-born Murray short-necked turtle Emydura macquarii hatchlings from wild-caught females resulted in some surviving for 1–3 years after release. The number of hatchlings that were recaptured over a three-year period was similar at both lagoons (38 of 328, 12% and 30 of 281, 11%) (number of released hatchlings taken from methods). In 1996–1997, gravid female turtles were captured and induced to lay their eggs (number of turtles and method not given). Eggs were artificially incubated, and hatchlings were released in to one of two lagoons (281 and 328 hatchlings each). Fox control was undertaken at one lagoon in May 1997 to January 1999 using poison baits and shooting. Recapture of turtles was carried out in 1998–2000.

    (Summarised by: Maggie Watson, William Morgan)

  2. Remove or control predators using lethal controls: Tortoises, terrapins, side-necked & softshell turtles

    A replicated, controlled, before-and-after study in 1996–2000 in an area with four lagoons in south-eastern Australia (Spencer & Thompson 2005, same experimental set-up as Spencer 2002) found that removing foxes Vulpes vulpes resulted in higher nesting success of Murray short-necked river turtles Emydura macquarii and broad-shelled turtles Chelodina expansa and higher survival of female short-necks compared to areas with no removal. Nest predation was lower after fox removal (short-necked turtles: <50% nests predated; broad-shelled: 18–38% predated) compared to areas with no fox removal (short-necked: >85% predated; broad-shelled: 57 and 50% of 7 and 10 nests) and before fox removal started (short-necked: 85–93% of 12–29 nests predated; 55–70% of 8–11 nests) (results were not statistically tested). Survival of female short-necks was higher following fox removal (97–98% survival) compared to areas with no removal (93–95%) and before fox removal (94 and 95%), though no effects of fox removal were found for short-neck males (95–99% survival), juveniles (69%), or any group of broad-shelled turtles (84–92%). In May 1997 to January 1999, fox control was carried out at two lagoons by burying poison baits (35 g FOXOFF baits; 150–200 m apart; 48 baits/site, laid every 1–2 months) and shooting foxes. A further two lagoons had no fox removal. In 1996–1998, searches for turtle nests were conducted in late autumn and trapping was conducted every 14–18 days in September–March.

    (Summarised by: Maggie Watson, William Morgan)

Output references
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