Global Warming Endangers Yet Another Species

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Numerous global-warming studies have been published recently, so I want to focus on this critical issue about once a week. Organic living and environmentalism should go hand in hand, and the more information you have, the greater your ability to counter the arguments of climate-change skeptics.


The latest casualty may be the world’s crocodile population. With temperatures on the rise, these animals have a harder time finding mates. For crocodiles, gender is not determined genetically, but by embryo temperature during incubation, according to Dr. Alison Leslie, chair of the University of Stellenbosch’s Department of Conservation Ecology in South Africa (pictured here with a baby croc).

“A difference of 0.5º–1ºC in incubation temperature results in markedly different sex ratios,” says Dr. Leslie, principal investigator of Earthwatch’s Crocodiles of the Okavango Delta project. Research shows nest temperatures of about 32º–33ºC result in males, while lower or higher temperatures result in females.

“More female hatchlings due to the cooler or hotter incubation temperatures could lead to eventual extirpation of the species from an area,” says Dr. Leslie, who monitors crocodiles’ diet, health, movements and reproductive biology. Populations have dwindled dramatically in Botswana because of hide hunters’ overexploitation and conflicts with nearby communities.

“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,” Dr. Leslie says. For more than eight years, in both Botswana and South Africa, she has been working with the Earthwatch Institute to change this. Next year, she will embark on a new study of crocodiles along Zambia’s Zambezi River.

Photo: Susy Bunker/Courtesy of Earthwatch

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