Newswise — New research shows that elephants in professionally managed zoological facilities have life expectancies similar to elephants in the wild. The finding, published in the August edition of the journal Zoo Biology (Volume 23, Issue 4), refutes a 2002 study that claimed wild elephants typically live longer. The new research used a different testing methodology, which its authors say corrects these earlier findings.
The new elephant longevity and life expectancy study was conducted by Robert J. Wiese, Ph.D., Director of Animal Collections at the Fort Worth Zoo, and Kevin Willis, Biological Programs Director, Minnesota Zoological Gardens. Both zoos are accredited members of the American Zoo and Aquarium Association (AZA), North America's only accrediting organization for professionally managed aquariums and zoos.
Wiese and Willis measured the life expectancies of elephants in professionally managed zoological facilities in North America and Europe, using the same data set employed by the 2002 study that determined wild elephants generally outlive elephants in such locations.
That analysis, however, did not account for the estimated life expectancies of elephants still living and achieved its results by calculating a simple arithmetic mean only for deceased elephants. Wiese and Willis take issue with that methodology. The new study calculates findings in two ways, including life-table analyses commonly used for studying animal populations and survival analyses commonly used by the biomedical community for assessing whether drug and other therapies extend the lives of cancer patients. The new research invalidates the results of previous studies, finding the exclusion of living animals to underestimate actual life expectancy, they say.
"The question of life expectancy is very complex and can't be answered by just picking an average. You have to use a method of analysis that is more appropriate for the animals' biology and the data available. Calculating an average is the easiest way to do it but, like with most things, the easiest way may not be the best or the most valid," Dr. Wiese said.
The new study finds the average life expectancy for female Asian elephants in professionally managed zoological facilities is 47.6 years in Europe and 44.8 in North America. Calculations for African elephants are less robust due to less available data. The current female African elephant life expectancy in professionally managed zoological facilities is 33 years but researchers say that number is likely to increase with more data, as it has increased over the past 10 years.
All of these life expectancy values are similar to the life expectancy of wild elephants for which data are available.
"It is gratifying to see that elephants in professionally managed zoological facilities do have long life expectancies when you analyze the data correctly," said Dr. Wiese.
From the zoo perspective, this research confirms long-standing assurances that AZA accredited zoos are excellent places for elephants and other animals to be. AZA standards for professional elephant care and management are this nation's highest, according to Sydney Butler, Executive Director of the AZA.
"Animal care is at the core of everything we do," Butler said. "Not only do we focus on the daily needs of elephants and all other animals, but we provide expert care based upon the most up-to-date research available and pursue the need to conserve wild species and habitat. We are passionate about educating every person who walks through our gates about animals and animal welfare, at any age and with any degree of experience."
Studying the longevity and life expectancies of elephants in professionally managed zoological facilities is complicated by the relative paucity of data, Dr. Wiese says. The majority of Asian elephants in AZA accredited zoos and other professionally managed facilities arrived in the1960s and early 1970s, he explains. Many of these elephants still thrive. The most accurate life expectancies will not be gauged until at least a full generation of elephants has lived in these facilities.
"The best data set we have is small, only about 600 elephants in the database. Of the 600 elephants, about half are still alive. Human demographers, by contrast, typically base their work on the records of millions of people," Dr. Wiese illustrates.
Elephant husbandry and professional care in zoological facilities has greatly improved over the past decade and will continuously get better as elephant experts refine and expand their knowledge, Dr. Wiese says. Elephants in AZA accredited zoos are provided with professional care according to strict elephant welfare and management guidelines.
There simply haven't been elephants kept under modern elephant husbandry practices in professionally managed zoological facilities long enough to know by how much they may outlive wild or logging camp animals, the new research concludes.
"When we have a complete set of data we expect that results will be even better because of constant improvements as we learn more about elephant husbandry and welfare," Dr. Wiese says.
Wiese and Willis conducted their study in part due to their frustration over a range of longevity and life expectancy studies in zoo animals with miscalculated results based upon simple arithmetic means.
"We see this mistake repeatedly in data from other animal species," Dr. Wiese says. "Using the simple arithmetic mean to describe a non-normally distributed age of death is a common error."
Founded in 1924, the American Zoo and Aquarium Association (AZA), is a nonprofit organization dedicated to the advancement of zoos and aquariums in the areas of conservation, education, science, and recreation. AZA currently has 212 accredited members in North America, Bermuda and Hong Kong. Look for the AZA logo whenever you visit a zoo or aquarium as your assurance that you are supporting a facility dedicated to providing excellent care for animals, a great experience for you, and a better future for all living things. With its more than 200 accredited members, AZA is a leader in global wildlife conservation, and your link to helping animals in their native habitats.
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Zoo Biology (Vol. 23, No. 4, Aug-2004)