I was tired when I arrived home tonight. The trip home involved a stop at Whole Foods. As if the store wasn’t huge enough, the check-out lines were long and I tried a couple of lines before settling on one. Did I choose the right one, in the end?

Somewhere on Sable Island off the coast of eastern Canada, a wild horse was doing the same thing as she looked for grazing space, according to new research just published by Philip McLoughlin, associate professor of biology at the University of Saskatchewan.

In a paper in the Journal of Animal Ecology, McLoughlin and his colleagues describe the habits of the famous wild horses at Sable Island National Park Reserve off the Nova Scotia coast.

“We found that not only did the horses ?shop’ for habitat patches in which to feed, they adjusted their preference for vegetation types to equalize what was used when more horses moved into the area,” he said.

The behavior mirrors how human shoppers frantically search for the shortest line to pay for groceries, moving from the express check-out to a regular check-out depending on the length of each line, or decide at which store to shop, based on which store is thought to be busiest and the travel time to get there.

“The horses moved across the length of Sable Island to minimize competition as population size increased, much as we might choose among stores to shop at,” McLoughlin said.

The Sable Island horse population has increased 42 per cent to more than 530 animals since the researchers began the planned 30-year research program in 2008.

McLoughlin explained that jostling for a better position in line or moving to a different store actually results in every shopper ending up spending roughly the same amount of time waiting in line, since everyone is thinking the same thing and pursuing the same strategy to get ahead.

“It’s called density-dependent habitat selection,” he said. “What is unique about our study is that it showed how it occurs in the Sable Island horses across two different scales within a habitat, but also among habitats – that is, within a store, but also among stores.”

The horses also appeared to consider other costs, such as travel, well. They were reluctant to drop everything and move to the other side of the island in search for food, even if competition was increasing. A sort-of ?store loyalty’ applied until things got too crowded.

“This work is helping us to understand what humans and animals share in our behaviors about economics,” McLoughlin said. “It may not apply so much to our shopping habits, but how we might maximize the effectiveness of where we drill for oil and deploy fishing fleets, for example.”

The work is also opening up a window into understanding how populations of animals function based on individual decisions, and what it means for the conservation of species. The knowledge could help answer key questions about the long-term viability of the Sable Island herd, whose small size and history of inbreeding make it much like an endangered species.

The next time you find yourself zigzagging between checkout lanes, or counting what’s in your basket to see if you can sneak into the express lane, think about those wild horses in Canada. We’re all just victims of density-dependent habitat selection, in one way or another, when the parking lot gets crowded and the lines get long.

Thanks to the University of Saskatchewan and Western College of Veterinary Medicine for providing a summary of Dr. McLoughlin’s research.