Stressed-Out at the Zoo

       

Amboseli Elephants (Photo courtesy of Cynthia Moss--ATE)

 

Life at the zoo is a killer for elephants, according to a new study published in Science.  Researchers looked at data on global zoo populations from 1960-2005 and compared them to survival in the wild at Kenya’s Amboseli National Park for African elephants and in the Burmese logging industry for Asian elephants.    

The numbers for African elephants are particularly stark:  A median lifespan of 16.9 years in the zoo versus 56 years in the wild.  The likely cause, according to the authors, is stress and/or obesity.

An infuriated response to the Science study comes from the Association of Zoos and Aquariums (full  disclosure:  I was the keynote speaker at one of their conventions a few years ago).   Paul Boyle, a vice president there, argues that measuring performance based on mortality records from 1960 makes about as much sense for zoos as it would for heart transplants:  Conditions have come a long way since then.  The data also comes from European, not American, zoos, Boyle notes.  He says that for accredited American zoos, elephants live as long in captivity as they would in the wild, and he accused the Science authors of using “smoke and mirrors” and “manipulating data” to serve an unspoken anti-zoo agenda.  Boyle also argued that with Asian elephants broken up into tiny populations in the wild and “on a trajectory for extinction,” captive breeding in zoos is essential to maintain genetic diversity.

So how can zoos keep elephants with less stress on the animals?  

Larger, more natural enclosures help.  Keeping track of stress levels, by measuring cortisol in their droppings, can also alert zookeepers when a particular animal is in trouble.  As Stanford stress researcher Robert Sapolsky put it in his book Why Zebras Don’t Get Ulcers, “If you want to know if the elephant at the zoo has a stomache, don’t ask the veterinarian, ask the cage cleaner.”  (By the way, Sapolsky says zebras do get ulcers under one unnatural circumstance–after first being transferred to the zoo.  Zoo animals generally also experience an increase in reproductive diseases, according to a previous article in Science.)  

In the new Science article, the researchers call for ending  the importation of elephants from their native countries and minimizing inter-zoo transfers. They also suggest that breeding elephants should be restricted to those zoos that exhibit no harmful effects in their captive-born animals.

Another study, published Tuesday in the Royal Society Proceedings B, suggests that keeping elephants in relatively normal social groups can help, particularly during transfers.  Stanford post-doc Noa Pinter-Wollman found that elephants being translocated between national parks in Kenya liked to stick together, much like human immigrants forming local neighborhoods in the new country.

 

Recommended reading:

“Compromised Survivorship in Zoo Elephants,” by R. Clubb at Royal Society for the Prevention of Cruelty to Animals in West Sussex, UK; M. Rowcliffe; K.U. Mar at Zoological Society of London in London, UK; P. Lee at University of Stirling in Stirling, UK; P. Lee; C. Moss at Amboseli Trust for Elephants in Nairobi, Kenya; K.U. Mar at University College London in London, UK; G.J. Mason at University of Guelph in Guelph, ON, Canada.

Sapolsky, R. Why Zebras Don’t Get Ulcers.  

Vogel, G. “A fertile mind on wildlife conservation’s front lines,” Science 294, 2001