Study: Feral Horses 'Shop Around' for Ideal Living Areas

Study: Feral Horses 'Shop Around' for Ideal Living Areas

Located about 200 miles southeast of Canada’s Nova Scotia, Sable Island is home to around 500 horses—entirely independent of human handling and management—and only about five humans.

Photo: Philip McLoughlin, PhD

Imagine a grassy island inhabited almost entirely by a small group of wild horses. Now imagine that same island, several years later, inhabited almost entirely by a large group of wild horses. How will their use of habitat on the island have changed?

That’s the question Canadian researchers set out to answer, working with real feral horses on a real grassy island known as Sable Island. Located about 200 miles southeast of Canada’s Nova Scotia, Sable Island is home to around 500 horses—entirely independent of human handling and management—and only about five humans.

Philip McLoughlin, PhD, associate professor of biology at the University of Saskatchewan in Saskatoon, and colleagues have been tracking the Sable Island horses' movement patterns and population density (number of horses in the same area) for the past five years. He recently confirmed that feral horses choose their habitat depending on population density. In other words, McLoughlin said, the horses appear to “shop around” for the best place to live under the circumstances.

“Horses can graze in the best grassland when density is low, but then they are forced to move and use poorer habitat when density increases,” McLoughlin said. This happens at two different levels: along the whole island as well as within regions of the island.

It’s like humans shopping for a home, he said. You might want to buy a penthouse in New York City, but competition drives the prices up so you opt for a third-story apartment in Brooklyn instead. If population density is low, however—meaning, if there aren’t very many people living in New York anymore, you might be able to get that penthouse after all.

On the larger scale, he said, if population is really low, people might give up living in the city entirely “if living in the country is better for your survival and reproduction,” McLoughlin said.

While this shopping around sounds obvious to us, it’s actually the first time researchers have shown it to be true of free-roaming horses, McLoughlin said. “It might seem like common sense for people to behave like this, but it is in fact rarely shown in other animals,” he said. “It’s neat that it does occur.”

This information is also very useful for current conservation projects for the horses on the island. Knowing horses’ preferred habitats when density is low will help make sure those preferred areas are available to them after the numbers drop again.

Although Sable Island's feral horse population has increased 42% since the start of McLoughlin’s study in 2008, this increase doesn't guarantee the breed's survival. The horse is now government-protected, but excessive inbreeding has made it susceptible to extinction if conservation efforts are not carried out, McLoughlin said.

Since 2008, McLoughlin’s team has been tracking all horses as they live and die on the island—around 800 total, although there have never been that many at one time, he added.

The team performs all identification using photography and coat pattern notation, without touching the animals. While unhandled, the horses are mostly “ambivalent” to the few humans they see, he said.

The study, "Local density and group size interacts with age and sex to determine direction and rate of social dispersal in a polygynous mammal," was published in Ecology and Evolution

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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