Many of the world’s 27 species of crocodylians will soon be either totally or locally extinct due to human population expansion and intensive land-use for agriculture depleting the water bodies, which provide succour to crocs, said a University of Queensland researcher.
Emeritus Professor Gordon Grigg of UQ says the fact that these reptiles had survived millions of years was no good owing to current rate of human expansion and encroachment of natural resources. “The current human population level and its magnitude and rate of resource consumption are unprecedented,” Professor Grigg said.
Only those crocs living in remote wetland habitats in which humans see no benefit may survive into the future, he said. Some crocodylians might have already become extinct if not for active conservation management undertaken in the second half of the 20th Century.
“For some species, the incentive for conserving them has been the commercial value of their hides, but that is dependent upon its use in high fashion garments and accessories, and that is a somewhat fragile foundation,” he said.
On flip side, the rising temperatures and sea levels may turn a more positive note for crocodylians, as it may create more habitat that will be suitable for any species to survive the human onslaught, he said wryly.
The largest living crocodiles, the estuarine or saltwater crocodile (Crocodylus porosus), are found in Northern Australia and can grow to six metres and weigh more than 900 kilograms.
Professor Grigg said estuarine crocodiles, also known as Indo-Pacific crocodiles or “salties”, were one of the luckier species because human populations across Australia’s north were unlikely to increase significantly in the next few decades. They might be among the survivors.
Professor Grigg and illustrator and biologist David Kirshner, in their recent book, Biology and Evolution of Crocodylians, reviewed the biology of the crocodiles, alligators, caimans and gharials, and also discusses the great diversity of their gigantic extinct ancestors, some of which were probably warm-blooded.