Global warming may threaten crocodiles

26/08/2006 00:00:00 November 2006. With global temperatures generally on the rise, crocodiles may have a harder time finding mates. For crocodiles, gender is not determined genetically, but by embryo temperature during incubation, notes Earthwatch-supported scientist Dr. Alison Leslie, of Stellenbosch University, South Africa. ‘A difference of 0.5 - 1ºC in incubation temperature results in markedly different sex ratios,’ says Leslie, principal investigator of Earthwatch’s Crocodiles of the Okavango Delta project. Research shows that nest temperatures of about 32-33 degrees Celsius result in males, while temperatures higher and lower result in females. Temperatures within a nest can vary from the top to the bottom of the nest, and can result in mixed-gender hatchlings.

‘More female hatchlings due to the cooler or hotter incubation temperatures could lead to eventual extirpation of the species from an area,’ says Leslie.

‘Even though crocodilians have been around for millions of years, and as important as these creatures may be in the systems they occupy, they are a much understudied species,’ says Leslie. For more than 8 years, in both Botswana and South Africa, Leslie has been working with the support of Earthwatch Institute to change that.

In 2007, Leslie will leave behind her Okavango research camp (in the capable hands of staff member Sven Bourquin), and will embark on a new study of the crocodiles along Zambia’s Zambezi River.

Earthwatch volunteers will continue to assist her as she assesses the conservation needs of this population and surveys local villagers about crocodile impacts.

Earthwatch Institute is a global volunteer organization that supports scientific field research by offering members of the public unique opportunities to work alongside leading field scientists and researchers. Earthwatch's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment. The year 2006 marks Earthwatch's 35th anniversary.