4. Faunal Predation of Marine Turtle Egg4. Faunal Predation of Marine Turtle Eggs

4. Faunal Predation of Marine Turtle Eggs

Introduced and native fauna is known to prey upon marine turtle eggs. Feral pigs, foxes, feral dogs, dingoes, bandicoots and goannas have been identified as predators on marine turtle eggs in parts of mainland Australia, and goannas are thought to be a problem on some islands (Bustard 1972, Lemm 1996, Limpus and Reimer 1994, Morris 1987). The magnitude of the problem is not known across the whole range of marine turtle nesting habitat. Where populations are identified as a priority, control programs will be needed to increase nesting success.

Predation by the European red fox has been identified as a key threatening process. A threat abatement plan has been prepared by the Commonwealth to ameliorate the impact of foxes on native species (Environment Australia 1998b). Foxes are a significant predator on the central Queensland coast (loggerhead turtles especially) (Limpus and Reimer 1994) and mainland nesting sites in Western Australia (loggerhead and green turtles) (K. Morris pers. comm.). Lemm (1996) observed that, for nearly 75 per cent of all nests with some level of predation, the predators were foxes. Fox predation of loggerhead turtle (and some green turtle) nests occurs in Cape Range National Park adjacent to Ningaloo Marine Park, Western Australia. A program to control foxes and protect turtle nests takes 60-80 foxes annually (K. Morris pers. comm.). The establishment of a poison-baited buffer zone adjacent to the Cape Range National Park during the nesting season would increase the level of protection at a critical time.

Choquenot et.al. (1996) recognised that the major environmental impacts of feral pigs are predation on native species and habitat degradation. Feral pigs are responsible for high levels of nest predation on nesting beaches used by flatback turtles particularly on Cape York Peninsula.

Control activities in remote areas offer considerable scope for Aboriginal and Torres Strait Islander people to become involved. Technology for poisoning feral predators and excluding native predators is available and can be used where predation is particularly severe or where a priority has been identified, for example fox predation on east coast loggerhead nests. Some estimate of nest predation will be valuable in determining management actions for controlling feral pests and native predators of eggs.

The marine turtle populations affected by predation have been identified as: loggerhead turtles from the eastern and western Australian populations; green turtles from the southern Great Barrier Reef, Gulf of Carpentaria and North West Shelf populations; hawksbill turtles from the north-eastern Australian populations; olive ridley turtles from the Northern Territory; and flatback turtles from Arnhem Land, Gulf of Carpentaria, Queensland and North West Shelf populations.