VOA标准英语2012--To Avoid Humans, Tigers Take Night Shift

To Avoid Humans, Tigers Take Night Shift

Tigers don’t have a reputation for being very accommodating, but a new study challenges the long-held conservation belief that these large carnivores need lots of people-free space.

This new understanding is especially critical because, since the start of the 20th century, the tiger population has declined by 97 percent to approximately 3,000 worldwide largely due to loss of habitat from encroaching cities and agriculture.

Captured on camera

Michigan State University graduate student Neil Carter set up motion-detecting camera traps in and around Nepal’s Chitwan National Park to study human-tiger interaction.

The park, nestled in a valley of the Himalayas and protected by army patrols, is home to about 120 tigers.

But the area is home to people, too. Tourists visit the park and local villagers live on its periphery 1, where tigers also roam.

A tiger’s eyes glow during the night on the same foot paths and roads humans use during the day to collect wood and grasses. (Center for Systems Integration 2 and Sustainability, Michigan State University) 

Carter says the cameras, at 80 different sites, captured intense activity inside and outside the park.

“What we started seeing was tigers were everywhere, people were everywhere and obviously they could not have been in the exact same places at the exact same time because there will be reports of all kinds of conflicts, left and right," he says. "So what we ended up discovering was that the tigers were displacing their time and becoming more active at night instead of during the day.”

Switch to night shift

While tigers typically move around at any time of the day or night, the camera images show that the vast majority of the big cats were more active at night, even roaming outside the park on the same dirt roads and narrow footpaths 3 used by humans. Carter was surprised to find the tigers shifted their activities in time, but not space, despite such intense human presence.

“There was no relationship between the number of vehicles or people or even different types of people. Tigers were there. They were everywhere. They were widespread and ubiquitous and also the prey 4, their prey, was really abundant," he says. "And so that I think is really sort of the critical link. Tigers are not going to leave an area that has their food.”

New hope for endangered wildlife

Carter says the results of the study could change conservation management, especially since about 80 percent of tiger habitat is now dominated by humans. He says the key will be to figure out what conditions foster the co-existance the study documents.

“We want to see if we can duplicate that in all these multiple use forests and areas where tigers occur, but people also depend on those forests.”

Carter says the study, published in the Proceedings 5 of the National Academy of Sciences, shows promise that humans and wildlife can thrive in the same environment, but that more work must be done to understand the complicated connection between the two worlds.