AbstractThis study was undertaken to quantify the ecological impacts of marine turtle nest depredation by feral pigs on the west coast of Cape York Peninsula, to investigate seasonal patterns and characteristics of feral pig nest depredation activity in a marine turtle nesting habitat and to quantify nest depredation impacts from other feral and native vertebrate species. The sur\Tey was undertaken on 42kms of beach north-west of Weipa, previously identified as breeding habitat for Natator depressus and Lepidochelys olivacea. Weekly surveys were undertaken over a 12 month period beginning in May 2004.
Two hundred and fifty four marine turtle nests were surveyed, and the results indicated that feral pig nest depredation activity resulted in 70.47% (n = 179) of all nests being destroyed within 10 weeks after initial oviposition, with dingo nest depredation rates recorded at 5.51% (n = 14), goannas at 2.36% (n = 6), and nest depredation from human egg harvesting activity at 2.36% (n = 6). Feral pigs started depredating both N. depressus and L. olivacea nests as soon as the breeding seasons commenced. Frequency of feral pig nest depredation increased in response to increases in nest laying. Both turtle species recorded the highest nest depredation rates from feral pigs in the first week after oviposition, with a marked decline in subsequent weeks. There .was a direct correlation between the density of both N. depressus and L. olivacea nesting and feral pig nest depredation activity. Statistical analysis indicated that feral pigs display: no significant preference · between N. depressus and L. olivacea nests; no significant preference for nest sites located on open beach for either species; and no significant preference between nests of either species during the first week after oviposition.
The study concludes that the ecological impacts of egg loss resulting from feral pig nest depredation in this particular breeding habitat are substantial, and proposes that if this level of nest depredation was being replicated in other marine turtle nesting beaches in northern Australia then the long-term sustainability of these breeding cohorts are extremely tenuous. Recommendations are made for further research to develop effective target-specific management programmes, especially suited for implementation in protected areas, which will eliminate the specific feral pigs responsible for nest depredation in marine turtle breeding habitats.
|Date of Award||Dec 2005|
|Supervisor||Michael Guinea (Supervisor)|