Fences, roads and railways are cutting up the world like the bars of a cage. They can appear like prison bars to many humans. How do other land animals see them?
With the footprint of humanity already stamped on about 50 percent to 70 percent of the world, it was likely that human activities would have modified the way animals moved. However, until recently not a great deal of effort had been spent on assessing the impact of human activities such as infrastructure and agriculture on the movement of individual species. Little hard data had been collected on the impact that such development is having on animals on a global scale.
In 2014 a group of researchers in the United States decided to change all this. They launched a global study to look at movement across many different species and throughout the world to see what the impact of human development was on the way they moved. The study was led by Marlee Tucker, a researcher at the Senckenberg Biodiversity and Climate Research Centre and the Goethe University, both located in Frankfurt.
These scientists belonged to a new and growing discipline called “movement ecology”, which had by then been around for about six years. What this brand of ecologists aims to do is to track animals with the intent of understanding how, when and why they travel, not just on the scale of individual species but as part of a larger, global picture of animal movements.
“In the field of movement ecology there is a lot of work being done on a very small scale – tracking single species or single populations in a single location,” Tucker says. “We thought it would be nice to think about doing this across species and the globe.”
Four years and over one million emails later, in January 2018, their groundbreaking global study was published in the academic journal Nature. By then, 57 species of animals, 803 individual animals and 114 researchers from across the globe had contributed to give the scientists the first hard data of how the human footprint was impacting on animal movement across the world – and it wasn’t good news.
What the researchers found was that animals as small as a pocket mouse and as large as an elephant move far less in landscapes that have been altered by humans – a finding that could have implications for the survival of ecosystems and the need to protect the ancient routes of migratory species.
The researchers discovered the African forest elephant living in a high human footprint area moved about 13.5 miles on average over 10 days, while an elephant living in a low footprint area moved on average 27 miles.
“We used GPS animal tracking data collected every hour for at least two months,” she says, “and for each longitude and latitude position we were able to match to the corresponding value on the Human Footprint Index to see how humans impacted on the movement of animals.” It’s enough to make Facebook jealous.
GPS was used because it is more accurate than other technologies such as radio. If it can tell our friends what Starbucks we are sitting in, GPS can track animals to a 10-metre to 20-metre degree of accuracy.
Box: The science of GPS animal tracking
“We can use GPS animal tracking to look at the movement of wild elephants across the whole of Africa,” says Iain Douglas-Hamilton. “The reason why we do it is that we can look at their corridors, their core areas, and we can provide better protection from poachers.
“We attach an algorithm to the signal from the elephant’s GPS transmitter that tells us if they are moving too fast, or too slow, or if they are becoming mobile. This data is then shared widely, from rangers to national parks.”
The elephant’s latest location can be seen by a tap of a finger on the screen of a phone or tablet by researchers or rangers, to help them find the animal, whether they are in a plane or jeep or on foot.
“Seeing the data in this way has an unexpected effect,” says Douglas-Hamilton. “We have found that the people who use our app become extremely interested in the fate of their animal. They send their patrols to go where the elephants are. They get a deeper insight into what the elephants are doing with their space, and security and managers check on them more often.
“We can even walk into the government offices and show the minister where the elephants are, and ask him what is he going to do about it.”
Moving on up
The global Human Footprint Index represents the relative human influence in large distinct ecological areas known as biomes, expressed as a percentage. Its purpose is to provide an updated map of the impact of humanity on the environment in specific locations, which can be used in wildlife planning, management and research.
Researchers working on Tucker’s project were then able to share the data on a revolutionary new online platform called Movebank – funded by the Max Planck Institute for Ornithology – that is a part data repository, part “data ark”, designed to safeguard data on animal movement for generations to come.
“We looked at the movement of animals on an hourly scale, then up to 10 hours,” says Marlee Tucker. “On the shorter time, day to day we didn’t see anything. From eight hours onwards, we saw an effective reduction in movement.
“On average, mammals move between two and three times shorter distances in human-modified landscape than they do in wild landscapes.”
Box: The 21st-century ark
Movebank is a free online data repository of over a billion animal tracking data points and 17,000 users hosted on the servers of the Max Planck Institute for Ornithology. It helps researchers manage, share, protect and analyse their data as well as preserve it for posterity.
“Movebank doesn’t do conservation, but we enable conservation to occur,” says Roland Kays, a biologist at North Carolina State University, co-founder of Movebank and a co-author on the movement project.
“I think our biggest contribution so far has been to enable these big comparative studies to occur. It also gives a second life to research that has already been done – and that can happen over and over again.”
“The GPS revolution means that researchers need a way to store and interact with larger and larger sets of animal tracking data, and Movebank is becoming the primary way for them to do this,” says Kays. “It also means that people are increasingly feeding live info from the animals they are tracking directly into Movebank.
“We are also getting more and more people making their data on Movebank available to the general public when they are done with it.”
The platform even acts as a kind of “data ark”, preserving animal movement data for a future in which many of the species may be depleted or extinct.
“I have rescued cartons full of CDs of data that had been thrown away,” says Kays. “If you want to preserve that information, then it needs to be saved somewhere like this.”
There have been challenges too. One particularly large set of data on the movements of a troop of baboons caused plenty of problems.
“The challenge was how to draw 25 million data points on a screen in a way that let the users interact with them. We knew that we were going to get more data of this kind of size in the future – so I told our programmers that we had to know how to handle them.”
Then there is always the fear of cyber attack on a platform that poachers could use to find exactly where their next targets are. The thing of concern is the live data of elephants and other high-value poachable animals. It is something that we are on the lookout for – but I don’t think anyone’s trying.”
The next step, says Kays, is to find “a way to tell the amazing stories behind these animal movements”. They have already worked with schoolchildren, written a book and teamed up with National Geographic.
An elephantine issue for wildlife
One of the researchers who was a co-author on the project was Dr Iain Douglas-Hamilton, Oxford University academic and founder and senior scientist at the Kenya-based Save the Elephant. Dr Douglas-Hamilton conducted some of the first studies into the behaviour of wild African elephants back in the 1960s.
“We want to understand elephant decision-making,” he says. “And from the way they move we can understand their needs better, and we can use that for conservation.
“The reason why we got involved in the big project is that it was animal tracking on a grand scale. I liked the idea of asking a very simple question across a huge spectrum of animals that was global in scope.
“Movebank is vital. It is important that information can be shared quickly and saved for posterity so that people can analyse it again five, 10 or even 100 years in the future.
“I thought the project produced some interesting answers – and it was based on hard data.”
Why does it matter if animal movement is affected? Can’t animals just adapt?
“Some can live in a human-modified area and some can’t,” says Douglas-Hamilton. “Physical barriers like roads, fences and buildings may stop movement. Others may be attracted to these areas because human waste is quite tasty. Small species like foxes can adapt. Others, like zebra, can’t live in a human area.
“If animals can’t migrate then they can’t move through landscapes distributing seeds. It changes how predators and prey interact. If herbivores can’t move, then they will overgraze where they are.”
The study didn’t test to see whether the animals whose movement has been curtailed are demonstrating any signs of stress like zoo animals do – but what the project did do was highlight how ancient migration routes may be threatened by our need to get home five minutes faster.
“The long migration movements provide lots of ecological functions. Some animals may be able to adapt to the change, some won’t be able to adapt. It depends on what they are migrating.
“If they are migrating to escape bad weather, cold weather, which they might not able to cope with, you might see population decline. Or these species might just be pushed away from those areas and not be seen again.”
Douglas-Hamilton compares the impact on his wild elephants to being in prison. “Like humans, elephants are very adaptable,” he says. “But if you confine them, they lose their way of life, and much like humans in prison, it is not much of a life.
“Africa is a continent on the move, with development everywhere,” he adds. “But if we act now there is still space and time to keep corridors open and preserve the stability of ecosystems.”
Marlee Tucker is now working on a similar project about the movement of birds. She is blunter in her assessment of the problem. The results of her research are, she says, “a message and warning to policy makers and planners”.