Tuesday, October 19

Human Activity Forces Animals To Move Further To Survive, Study Finds | Wildlife


Human activity is fundamentally altering the distances that the world’s animals need to move to live, hunt and feed, according to a study that examined the impact on more than 160 species on six continents.

All of the activities changed the behavior of the animals, but the study found that destructive activities such as urbanization and logging affected the movement of animals less than sporadic efforts such as using airplanes, hunting, and recreation.

In addition to having a profound impact on animals, such as reducing their ability to feed and reproduce, the changes “point to a global restructuring of animal movement” that could have profound side effects, says the study published today in Nature Ecology and Evolution daily.

Dr Tim Doherty, a wildlife ecologist at the University of Sydney, said it was already well known that humans affected the movement of animals, with thousands of studies tending to focus on individual species or activities, but the information was disparate and had not been synthesized.

Doherty personally read the abstracts of 12,000 research articles drawn from academic journals around the world, before joining his colleagues to extract 208 relevant studies with enough useful data on how human activity had altered the distances traveled by 167 different species.

When human activities forced animals to move farther, such as when animals fled from hunters or had to navigate roads or avoid skiers or campers, they moved an average of 70% more in response.

“In Australia, the average person’s journey is about 10 miles, so 70% is like traveling an additional 11 miles,” said Doherty.

“If the animals are not moving naturally, then there is the possibility of wider impacts.”

Animals and impacts examined included:

  • Madagascar’s lemurs expand their range by more than half in response to logging

  • Brush-tailed possums in Victoria, Australia, moved 57% more in areas divided with roads compared to large forests

  • Moose in Sweden moved 33 times faster in an hour after being bothered by cross-country skiers

  • Texas tortoises traveled shorter distances in areas with cattle grazing

  • Mountain lions in the US moved more slowly if they heard human voices, which in turn increased the distances rodents traveled in the same area.

  • Flightless railway birds in New Zealand that help disperse seeds cover about a third less distance in areas close to camps

  • Reindeer in Canada move faster in response to the noise of oil exploration.

The research says: “Even a small change in movement can have a large impact on an individual, and when these costs accumulate across a population, reproduction rates and population viability can be compromised.”

Tracking changes in movement was important, because it showed how animals’ behavior was being altered when fleeing from humans, predators, or traveling to find food, shelter, or mates.

Some activities tended to shorten the distances traveled by the animals, such as urbanization, which facilitates the search for food for some animals.

Doherty, who began the research while at Deakin University, told The Guardian: “We found that about a third of the data we discovered reported a change in motion of 50% or more.

“That tells us that we as humans have a fairly broad impact on animals, but that they are not addressed.”

Birds advanced an average of 27% further in response to human disturbances, while mammals advanced 19% and insects 38%.

In the case of mammals, roads, agriculture, and aviation had the greatest effect on distances traveled, and grazing and hunting tended to extend the species’ home range.

“Most of the earth’s surface has been altered by humans, but there are some places that have not and must be protected,” said Doherty. “We need some places on earth where animals can do their thing.”

Last year, a study found that wild places were disappearing on a massive scale, with an area the size of Mexico turning in just 13 years from virtually intact landscapes to heavily human-modified areas.

Professor Corey Bradshaw, director of the Global Ecology Laboratory at Flinders University in South Australia, and who was not involved in the latest research, said the study confirmed much of what was known, but provided a “useful synopsis.” .

“The fact that most species increase movement in response to disturbance gives an interesting clue about the mechanism of anthropogenic pressures beyond the obvious, such as invasive predators, habitat loss or direct exploitation.”

Bradshaw said the study also illustrates how difficult it was to predict how an animal’s range might change once human activities began.

He said a revealing aspect of the study was the finding that disruption of recreation and hunting caused species to move more than habitat loss or fragmentation.

“It suggests then that even the so-called ‘non-invasive’ human presence can be potentially harmful.”


www.theguardian.com

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