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Extinction Countdown

Extinction Countdown

News and research about endangered species from around the world

Rare Success: Critically Endangered Gharial Crocodiles Have Record Hatching Year

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This week's blackouts in India have been blamed at least in part on the lack of rain during the annual monsoon season, which hindered hydropower production and increased the demand for electricity for use in agricultural irrigation. But the unusually dry year has also had at least one positive effect: it has helped to boost the population of a critically endangered species.

This year more than 2,000 gharial crocodiles (Gavialis gangeticus) have hatched and, more importantly, survived in India's National Chambal Sanctuary. Under normal circumstances, most gharial hatchlings would be wiped out by floods during monsoon season, but this year, thanks to abnormally low rain levels, the majority of newborns are expected to live. This could represent a major conservation success story for a species whose future not too long ago looked quite dark.

Honestly, I have not held out much hope for writing good news about the gharial, one of the world's rarest crocodilian species. Gharials were once plentiful, but overhunting for their skin and eggs drove their population down from somewhere between 5,000 to 10,000 individuals in the 1940s to fewer than 200 in 1975, the year they were finally protected. Despite captive breeding efforts, things weren't much better more than 20 years later. I first covered the gharial in 2007, by which time there were a grand total of just 200 breeding pairs, at least 80 percent of which lived in the Chambal River. That incredibly low figure started to drop further that year due to a mysterious illness striking the Chambal population. After nearly a year of study and more than 100 gharial deaths, scientists theorized that the animals had likely died from gout and kidney failure, probably caused by exposure to toxic chemicals in nearby polluted rivers. By then the number of adult gharials in the wild in India had dwindled to 100.

Those numbers had improved slightly by 2009 when I covered a team of scientists who were attaching RFID tags to the rare crocs' backs to learn more about their behavior and habitat use. Understanding how, when and why the animals traveled was essential to conservation efforts because captive-bred gharials were almost all dying after being released into the wild.

Flash forward three years and, at last, we have good news about the gharial. India Today reports that this year brought a record number of new gharial hatchlings in the river waters of Chambal Sanctuary. Of the 68 nests found and protected from predators by sanctuary staff this year, as many as 2,340 eggs hatched—more than double the number than in each of the last three years. And if that wasn't good news on its own, it seems that more of these young hatchlings may survive than in past years. "Mortality is usually higher in young gharials as they get washed away in floods, a usual phenomenon in the Chambal River, but this year appears to be an exception," said Sujoy Banerjee, deputy conservator of forests for the National Chambal Wildlife Division. A late and less severe monsoon season than usual gave the hatchlings enough time to grow up and increased their chance at long-term survival.

The wild population of adult gharials in India is still only around 200, but there are also some 1,300 juveniles not yet old enough to breed. Add in any hatchlings that survive from this year's breeding season and we could see a population boom in the next few years.

The species is hardly out of the woods. The Chambal River has been called one of the country's cleanest, but gharials sometimes travel to the nearby Yamuna River, one of the most polluted rivers in the country if not the entire world, which is probably why all those gharials died in 2007 and 2008. But even with the threats that remain, this is good news and well worth celebrating.

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This is my 400th Extinction Countdown article for Scientific American (and my 965th overall if you count the previous three incarnations of this blog). I want to take a moment to thank my fantastic editors and readers, the scientists and conservationists whose important work I have covered, and all those who take action to help the endangered species of the world. I could write another 10,000 articles and still barely scratch the surface of this critical topic, but keep reading and we'll see what we can accomplish together.

Photo: A gharial with a fish in its slender, fragile jaws by Siddhartha Lammata via Flickr. Used under Creative Commons license

The views expressed are those of the author and are not necessarily those of Scientific American.

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