Mammals move less in human-modified landscapes

New research has shown that elephants, like many other mammals, move on average distances two to three times shorter in human-modified landscapes than they do in the wild.

Published in the journal Science by an international team of over 100 authors, this is the first time this topic has been examined at a global scale and for many different species at once. The authors highlight that these results may have far reaching consequences for ecosystems and in turn, for society.

Most mammals are on the move every day while searching for food, to find a mate or to seek out shelter. Some larger mammals like zebra generally move longer distances, while smaller mammals, such as hares, usually cover shorter distances.

Dr Iain Douglas-Hamilton, co-author of the study, founder of Save the Elephants and Senior Research Associate with the Department, said: "As the human footprint rapidly expands across Africa elephants are getting pushed into ever-smaller spaces."

This constriction also affects 56 other mammals. We still have a short window in which we can define important wildlife corridors through the intensive tracking of elephants. If these are defended now they can save a vital part of the shrinking connectivity, not only for elephants, but for all wildlife.

Movement data from 803 individuals across 57 mammal species from around the globe were collected with GPS tracking devices that recorded each animal’s location every hour for at least two months. The researchers then compared these data to the Human Footprint Index that measures how much an area has been changed by human activities such as infrastructure, settlements or agriculture.

It was found that during a period of 10 days mammals only cover half to one third of the distance in areas with a comparatively high human footprint, compared to mammals living in more natural landscapes. However over shorter time scales, such as one hour, mammals do not move any differently across landscapes of varying human footprint. This means that the human footprint affects the ranging behaviour of mammals over longer time frames, but does not affect their movements at shorter time frames. The researchers are concerned that the reduced travel distances could affect ecosystem functions that hinge on animal movements. 

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