There’s a churning national conversation about the welfare of animals in zoos, and one of the biggest debates is about elephants.

Infertility, obesity and shortened lives are common afflictions among the zoo populations of these highly social, intelligent and enormous animals. Scientists have probed, in a limited way, how captivity affects them. Some zoo managers have closed elephant exhibits, saying their facilities couldn’t adequately support the animals’ needs. Critics say elephants have no place in zoos at all.

Among the major concerns are limited exhibit space — elephants roam for miles in the wild — and social groupings that are much smaller and less complex than the matrilinear herds of wild elephants.

Now a sweeping, first-of-its-kind study of nearly all elephants at accredited zoos in North America has applied epidemiological research methods to extract information that has often been missing from these debates. And some of its findings, published Thursday in PLOS One, are counterintuitive.

More than two dozen researchers, who gathered and analyzed data on 255 elephants at 68 zoos, found no link between the size of an exhibit and three key indicators of poor elephant welfare: obesity, reproduction problems or “stereotypical behavior,” such as repetitive rocking or swaying. Elephants that walked more each day, as measured by GPS recordings, were no less likely to be obese than their sedentary counterparts, said the lead author of the study’s overview, Cheryl Meehan, who is a research associate for the School of Veterinary Medicine at the University of California at Davis and executive director of the Animal Welfare, Research and Education Institute. 

To measure space, the researchers looked at zoos’ total elephant habitat sizes, which ranged from about 7,700 to 347,000 square feet, but also created a new metric to account for the fact that individual elephants use space differently from one another. They called this “Space Experience,” and it ranged from 1,200 to 170,000 square feet per animal.

“This was really surprising,” Meehan said. “This adds a twist to the current narrative, which is heavily biased toward this idea of more and more space is necessary and better.”

Instead, she said, the researchers found that the quality of the space was “extremely important.” Diverse enrichment activities and feeding methods — such as hanging or hiding food rather than plopping hay on the ground — were more closely linked to signs of positive welfare, particularly reproductive health. Hard floors were linked to musculo-skeletal and foot problems, as well as less lying down among African elephants, which the authors surmised could lead to sleep deprivation.

Big, stable and diverse social groups seem to be better for African and Asian zoo elephants of both genders. Elephants in those kinds of groups performed fewer repetitive behaviors such as rocking, Meehan said, while those that spent more time in isolation performed more.

Stereotypical behaviors can indicate poorer current welfare, but they can also “be a scar, if you will, of past experiences,” Meehan said. That’s relevant for another of the study’s findings: Elephants that had been transferred more times from one zoo to another displayed more stereotypical behavior.

“The physical, actual move can be stressful, but [the researchers] also point to the disruption in social life with respect to social bonds with elephants they were living with and also human caretakers,” Meehan said. “So the social piece is really deeply woven into the question about elephant welfare.”

Ron L. Kagan, executive director of the Detroit Zoo who more than a decade ago closed that zoo’s elephant exhibit because of concerns about space and cold climate, said the study is an important contribution to scientific literature on animal welfare in zoos. But he said he thinks its findings about exhibit size could be misleading. When it comes to elephants, which can roam dozens of miles each day in the wild, zoo space is always insufficient, he said.

“The problem is that we are using space in human terms, which for an elephant is an irrelevant scale,” Kagan said. “If we double the size of a house for a human, that is a huge difference. If you double the size of an environment for an elephant from half an acre to an acre, or from an acre to two acres, that’s irrelevant. … I think the conclusion may make people think that it’s not important, when in fact the problem is we’re not talking about space in the right way.”

He said the study’s broad focus also meant “it can’t reveal one of the most important questions of all, which is: Are elephants happy in captivity? And that’s what we need to get to.”

Meehan, too, characterized the research as a jumping-off point for decisions about elephant care, and one she said she hopes will add science to the debate that has been lacking in it. Zoo animal care, as the study’s overview paper said, is “still more of an art than evidence-based.”

The data for the study was gathered in 2012, mostly by the participating zoos. They took videos that researchers used to assess elephant behavior, sent weekly blood and fecal samples that were used to measure physiological indicators of stress, and provided detailed descriptions of elephant exercise, feeding, health, exhibit space and other management information. Meehan said the zoos’ role in providing the data could be viewed as a limitation, but it was the only way to give the research such a wide scope, and the diversity of data received indicated that it was strong.

The findings, she said, suggest zoos should consider more diverse feeding methods and activities for elephants in the short term — both things that don’t require major infrastructure changes. In the long term, she said, they should “move toward larger herds so that we can support the social needs of the elephants.”

An earlier version of this article incorrectly reported that space-per-elephant size among those studied ranged from 1,200 to 17,000 square feet. It has been corrected to report total exhibit sizes and what the researchers called “Space Experience.” 

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