Study

Defending against disparate marine turtle nest predators: Nesting success benefits from eradicating invasive feral swine and caging nests from raccoons

  • Published source details Engeman R.M., Addison D. & Griffin J.C. (2016) Defending against disparate marine turtle nest predators: Nesting success benefits from eradicating invasive feral swine and caging nests from raccoons. Oryx, 50, 289-295.

Actions

This study is summarised as evidence for the following.

Action Category

Remove or control predators using lethal controls: Sea turtles

Action Link
Reptile Conservation

Protect nests and nesting sites from predation using artificial nest covers: Sea turtles

Action Link
Reptile Conservation
  1. Remove or control predators using lethal controls: Sea turtles

    A before-and-after study in 2007–2010 on a sandy beach on an island off the coast of Florida, USA (Engeman et al. 2016) found that eradicating feral pigs Sus scrofa ended pig predation of unhatched loggerhead Caretta caretta and green turtle Chelonia mydas nests. In the nesting season after feral pigs were eradicated, no marine turtle nests were lost to pig predation, compared to 50 of 50 nests predated by pigs in the nesting season prior to their eradication, including 36 nests covered with nest cages. In 2005–2010, turtle nests were monitored daily throughout the nesting season on a 13.4 km long stretch of beach on an island (526 ha). In 2007, nest predation by pigs was observed for the first time (pigs were present on the island from 2001). In May–June 2008, a total of 39 feral pigs were eradicated from the island by trapping and shooting over bait. Following eradication, no spoor or other signs of feral pigs were found. The authors reported that pigs reinvaded the island in 2014. Thirty-six of the 50 nests monitored had been covered by partially buried cages (91 cm long x 91 cm wide x 76 cm tall, 5 x 10 cm wire mesh) to protect them from raccoon predation. After hatching, all nests were excavated to record hatching success and predation levels. See ‘Use nest cages’ for more details on their effectiveness.

    (Summarised by: Maggie Watson, Katie Sainsbury)

  2. Protect nests and nesting sites from predation using artificial nest covers: Sea turtles

    A study in 2005–2010 on a sandy beach on an island off the coast of Florida, USA (Engeman et al. 2016) found that using nest cages to cover sea turtle (loggerhead Caretta caretta and green Chelonia mydas) nests reduced predation by raccoons Procyon lotor but not by feral pigs Sus scrofa. Covering marine turtle nests with cages reduced nest predation by raccoons in five of six years (1–20% of nests predated) compared to uncaged nests (7–69% of nests predated). Cages did not prevent feral pigs from predating nests. In August 2007, 36 of 36 remaining unhatched caged nests and 14 of 14 remaining unhatched uncaged nests were predated by pigs. Caged nests took longer to be predated by pigs (20 days) compared to uncaged nests (8.5 days). Turtle nests were monitored daily throughout the nesting season on a 13 km long stretch of beach on an island (526 ha) in 2005–2010. Located nests were covered by partially buried cages (91 cm long x 91 cm wide x 76 cm tall, 5 x 10 cm wire mesh) to protect them from raccoon predation (54–159 nests/year were caged, 8–24 nests/year were uncaged). After hatching, all nests are excavated to record hatching success and predation levels. In 2007, nest predation by pigs was observed for the first time (pigs were present on the island from 2001). Pigs were eradicated from the island in 2008 but reinvaded in 2014. See ‘Use lethal controls’ for more details.

    (Summarised by: Katie Sainsbury)

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