The exponential increase in saltwater crocodile populations in the Northern Territory in recent decades may be partly a result of them preying on feral pigs, new research suggests.
Scientists who have analysed the diets of saltwater crocodiles in the Territory believe the reptiles have shifted from marine prey to predominantly terrestrial food sources in the last 50 years – driven specifically by an abundance of feral pigs.
Using stable isotope analysis of crocodile bones, which gives an indicator of longterm dietary habits, the researchers found that the carnivores feed on more land-based prey and have a less diverse diet than their historical counterparts.
The research, published in the journal Biology Letters, analysed differences between the diets of 24 contemporary saltwater crocodiles caught near Darwin and 22 historical specimens caught between 1968 and 1986.
The researchers measured changes in ratios of carbon and nitrogen isotopes. Hamish Campbell, a professor at Charles Darwin University and leader of the research project, said the carbon and nitrogen signatures were more depleted in the present-day crocodiles, indicating that they were feeding more on terrestrial food sources.
Lead Image: A saltwater crocodile in Kakadu national park. Research suggests the reptiles have been eating feral pigs in the NT in recent decades. Photograph: Caroline Berdon/AAP.
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