Human activity fundamentally changes the distances the animals of the world need to live, hunt and feed, according to a study examining the impact on more than 160 species across six continents.
All of the activities altered the behavior of animals, but the study found that destructive activities such as urbanization and logging affected the movement of animals less than sporadic attempts such as using airplanes, hunting, and recreation.
The changes point to a global restructuring of animal movement, which could have a major impact on the animals, says the study published in the Nature Ecology today. and Evolution Journal.
Dr Tim Doherty, a naturalist at the University of Sydney, said it was already known that humans influence the movement of animals, with thousands of studies tending to focus on single species or activities, but the information was diverse and was not yet synthesized.
Doherty personally read the summaries of 12,000 research articles from academic journals around the world before joining colleagues to extract 208 relevant studies with enough useful data on how human activities changed the distances that 167 different species moved.
When human activities forced animals to move further, such as when animals fled from hunters or had to negotiate roads or avoid skiers or campers, in response they moved on average 70% further.
“In Australia, the average human journey is about 16km, so 70% is like traveling 11km extra,” Doherty said.
“If animals do not move around in a natural way, there is a greater impact.”
The animals and impacts examined include:
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Madagascan lemurs expand their home range by more than half in response to logging
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Brush tracks in Victoria, Australia, moved 57% further in areas broken up by roads compared to large forests
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Moose in Sweden moved 33 times faster in the hour after being disturbed by cross-country skiers
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Turtles in Texas have traveled less distances in areas with grazing livestock
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Mountain lions in the US move more slowly when they hear human voices, which in turn increases the distances traveled by rodents in the same area
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Flyless tracked birds in New Zealand that help disperse seeds are about a third less distant in areas near campsites
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Reindeer in Canada move faster in response to noise from petroleum exploration.
The research says: “Even a small change in movement can have a major impact on an individual, and if these costs accumulate in an entire population, reproduction rates and viability of the population may be compromised.”
Detecting changes in movement was important because it showed how the behavior of animals changes as they flee from humans, predators, or travel to find food, shelter, or companions.
Some activities tended to shorten the distances for animals, such as urbanization, which makes finding food easier for some animals.
Doherty, who began research at Deakin University, told the Guardian: ‘We found that about a third of the data we discovered reported a 50% or more change in movement.
“It tells us that we as humans have a fairly large impact on animals, but that it is not addressed.”
Birds moved on average 27% further in response to human disturbances, with mammals moving 19% further and bugs 38%.
For mammals, roads, agriculture, and aircraft had the greatest influence on distances traveled, with grazing and hunting tending to increase the home range of species.
“Most of the earth’s surface has been disturbed by humans, but there are some places that have not had it yet, and it needs to be protected,” Doherty said. “We need some places on earth where animals can be left to do their thing.”
Last year, a study found that desert sites were disappearing on a large scale, with an area the size of Mexico transformed in just 13 years from virtually intact landscapes to areas heavily adapted by humans.
Prof Corey Bradshaw, director of the Global Ecology Lab at Flinders University in South Australia, who was not involved in the latest research, said the study confirms much of what was known, but it forms a ‘useful synopsis’. .
“That most species increase movement due to disturbance provides an interesting hint regarding the mechanism of anthropogenic pressure outside 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 home territory could change once human activities began.
He said one revealing aspect of the study was the finding that disturbance by recreation and hunting caused species to move more than habitat loss or fragmentation.
“This indicates that even so-called ‘non-invasive’ human presence can be potentially harmful. ‘