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In Nepal, endangered tiger kills critically endangered gharial. What does it mean?

  • A tiger entered the Kasara gharial breeding center in Chitwan National Park and killed three critically endangered gharials.
  • The incident raised concerns that as the tiger population in Nepal increases, the animals could turn to the crocodiles for easy food.
  • Conservationists, however, say that is unlikely as tigers have other animals to feed upon.

KATHMANDU —  On the morning of July 31, a tiger (Panthera tigris) entered the enclosure of the Kasara gharial breeding center in Chitwan National Park unnoticed. It observed the behavior of the crocodiles for a while and then attacked and killed three of them.

Before staffers arrived at the site, the tiger ate one of the gharials (Gavialis gangeticus) and escaped. When staff did arrive, they witnessed the massacre of a critically endangered species at the hands of an endangered species.

“The tiger sneaked in, as the fencing and barricade of the center wasn’t well-maintained,” said Bed Khadka, who recently retired after working at the breeding center for more than two decades. “It’s not the tiger’s fault. If we leave our doors open, our house would automatically be susceptible to theft.”

The incident received wide coverage in Nepal’s media as the government and its conservation partners have invested a lot of resources in conserving both species under threat of extinction.

Gharials prey on the big fish that would otherwise feed on their preferred catch species. Image by Phoebe Griffith/ ZSL

Fewer than 200 breeding adult gharials, known for their long slender snouts, are believed to live in the wild in Nepal. Since 1978, Nepal has been running a program to raise gharial hatchlings in captivity, in an effort to boost the wild population. Officials in breeding centers in Chitwan and Bardiya national parks collect eggs from riverbanks, provide a suitable environment for them to hatch in, and feed and raise the young gharials until they’re around 5 years old, at which point they’re released into the wild. A recent study has also found that gharials are the most distinct in terms of ecological functions and evolutionary features among crocodiles alive in the world.

In the case of tigers, Nepal is one of the cat’s 13 range countries, and the only one to have achieved the goal set 12 years earlier at the inaugural Tiger Summit in Saint Petersburg, Russia, to double the global tiger population by 2022. The country, which was home to 121 Bengal tigers (Panthera tigris) in 2010, now has 355.

A tiger in Nepal. Image courtesy of DNPWC/NTNC/Panthera/WWF/ZSL.

As the number of tigers increase, the strong and young ones occupy the core habitats and push the weak and old to the fringes, where food is not as abundant. These tigers are known to attack humans as well.

Following the July 31 incident, concerns have emerged that such tigers could prey on gharials who spend winter days basking in the sun. The tiger involved in the incident was reported to have suffered injuries following a clash with another tiger and has been pushed to the fringes.

Another question arises: With the population of gharials limited to a few hundred in Nepal, will loss to predation of even a single individual, bred and raised with so much effort and investment, deal a big blow to their population?

Conservationists, however, say tigers don’t pose a big threat to the gharials. “A tiger entering an enclosure and preying on gharials is an abnormal incident. But it is normal for tigers to prey on gharials in the wild,” said Khadka. “Yes, the gharials we release in the wild are not naturally trained to fend off tigers, but that doesn’t mean all the gharials we release will be eaten by tigers,” he added.

Conservationist Ashish Bashyal, member of the IUCN Crocodile Specialist Group, said gharials are not the preferred prey for tigers, as other prey species, especially deer, are abundant in their range areas. He cited a study in the Brazilian Amazon where jaguars (Panthera onca) prey on caiman (Caiman crocodilus and Melanosuchus niger) in the absence of their primary prey mammalian species due to seasonal floods. The study found that jaguars not only preyed on the crocodilians, but also the eggs of both species. “But in the case of Nepal, we have seen that the tigers have abundant primary prey to feed on,” he added.

The Status of Tigers and Prey in Nepal 2022 report commissioned by the government also suggested high abundance of prey for tigers. It reported an increase in prey density estimates within protected areas where tigers live. According to the report, in Chitwan and Bardiya, the two key habitats of tigers in Nepal, prey density increased from 71 square kilometers (27 square miles) to 100 km2 (38.6 mi2), and 78 km2 (38 mi2) to 90 km2 (34.7 mi2), respectively.

The report did note that both areas had relatively low populations of the large species tigers prefer, like sambar or wild buffalo. However, tigers will also prey upon smaller animals such as spotted deer and wild boar, relatively more common in all protected areas.

A male gharial guarding hatchlings. Image courtesy of Gharial Ecology Project/MCBT.

“It is highly unlikely that they will switch to gharials, as they have other options,” said conservationist Babu Ram Lamichhane, who specializes in tigers. “Tigers are considered a more specialist species compared to leopards and jaguars in terms of their diet, as they have a more limited diet,” he added.

“Also, the threat posed by tigers is at a much lower level compared to other threats gharials face such as destruction of habitat and disturbances in the river systems,” he said.

However, he added that the threat can’t be completely ruled out. “We have released more than a thousand gharials into the wild, but only a few hundred survive. Are tigers preying on them on a large scale? It is highly unlikely, but we’d need further studies to get a definitive answer.”

The tiger that killed the gharials in Chitwan was later caught and transferred to a cage. But as Nepal’s tiger population continues to grow, it is unclear how it will affect other species, especially those edging toward extinction.

Banner Image: Gharials bask in the sun at the Kasara gharial breeding center in Chitwan National Park, Nepal. Image courtesy of NTNC.

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Citations

Da Silveira, R., Ramalho, E. E., Thorbjarnarson, J. B., & Magnusson, W. E. (2010). Depredation by Jaguars on caimans and importance of reptiles in the diet of Jaguar. Journal of Herpetology, 44(3), 418-424. doi:10.1670/08-340.1

Status of Tigers and Prey in Nepal 2022. (2022). Retrieved from the Department of National Parks and Wildlife Conservation website: https://dnpwc.gov.np/media/files/Status_of_Tigers_Ic2ylSC.pdf