Study Finds Elephants In Zoos Live Shorter Lives A study comparing over 4,500 elephants revealed that zoo life may be harmful to elephant health. Georgia J. Mason, professor at University of Guelph in Ontario and lead researcher on the Science study, explains the findings and discusses what zoos can do to keep elephants healthy.

Study Finds Elephants In Zoos Live Shorter Lives

  • Download
  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

JOE PALCA, host:

From NPR News, this is Talk of the Nation: Science Friday. I'm Joe Palca. Up next, a mammoth issue. According to a brief report in the journal Science this week, living in a zoo shortens an elephant's life expectancy. The study compared Asian and African elephants living in European zoos with Asian elephants living on a reserve in Myanmar and African elephants living in a park in Kenya. According to the study, elephants in the wild or in other natural environments lived at least twice as long as elephants in zoos.

The study looked data from 1960 to 2005, and it's rekindled a long-simmering debate between animal-rights activists and those who believe elephants can be healthy and even happy in a zoo environment. Joining me now to talk more about it are my guests. First, Georgia Mason; she is the author of the study and a professor and the Canada Research Chair in Animal Welfare at the University of Guelph, Ontario, Canada. Thanks for talking to us today, Dr. Mason.

Dr. GEORGIA MASON (Animal Welfare, University of Guelph): Right. Thanks. Hi.

PALCA: And Paul Boyle is a senior vice president for conservation and education at the Association of Zoos and Aquariums in Silver Spring, Maryland. Welcome to Science Friday, Dr. Boyle.

Dr. PAUL BOYLE (Senior Vice President, Conservation and Education, Association of Zoos and Aquariums): I'm glad to be here. Thanks.

PALCA: And if you'd like to join the conversation, give us a call. Our number is 800-989-8255; that's 800-989-TALK. And we'll get started with you, Dr. Mason. What was the nature of your study? You were using records from - birth and death records from Europeans zoo populations, right?

Dr. MASON: Yeah, that's right. We had records for births and deaths from both the species kept in European zoos, and we compared them with two protected populations in Africa and Asia. We were interested in answering the question, given that zoo - animals in zoos get good veterinary care, good food, good water, are they living as long you would expect? So, that's why we looked at protected populations. We looked to African elephants in Amboseli National Park. And just to correct you slightly, the Asian elephants we looked at in Burma were, in fact, part of a logging population. So, they weren't in a reserve; they were working animals.

PALCA: Oh, I see. But they were - as I understand it, they were also - someone described them as quasi-domesticated, in the sense that they were being used and cared for as part of the operation.

Dr. MASON: Yeah, that's right. So, they're working animals, dragging logs. Yeah.

PALCA: Thanks for correcting that. So, basically, did I get it right? I mean, was your data basically showing that if you look at life expectancy, you see a much shorter time for elephants in zoos than you do in elephants in these two wild - well, not wild, but two natural populations?

Dr. MASON: Yeah, essentially. I mean, how much shorter depends on the species. We saw the least worrying picture for the African elephants, and in this species, we found that infant mortality in European zoos was pretty much fine. There was no difference between it and what you saw in Amboseli. Juvenile survivals - so, that's for animals aged between one and 10 - again, seemed just absolutely fine. But we started to see some signs of increased mortality rates in the adult population.

So, amongst the zoo animals, they just have less of a chance of reaching middle age and old age. So, they die at a faster rate in their 20s, 30s and 40s. And actually, in Europe so far, no African elephant has reached past the age of 50; although in Amboseli, over a third of animals would. But in this species, we saw some good news as well. We looked to see whether things had changed in recent years, because obviously husbandry and veterinary care have changed a lot since 1960, and for the African elephants, we found that there was a significant improvement over time. So, in recent years, the survivorship of the species has improved. So, that's great.

For the Asian elephants, which are the far the more endangered of the two species, the pattern was a bit more worrying. We could see no signs of improvement over time and that was true for infant mortality, juvenile mortality and adult mortality. There was just no significant difference over the four decades. And we found that for captive-born animals, there was a really a marked difference. So, the medium life span of a female elephant born into a European zoo was about 19. That means half are dead by 19; half live longer. And in the Myanmar working animals, the median life span was 42, so over twice as long.

PALCA: OK. Well, Paul Boyle, let me turn to you and say, I mean, what do you make of this? First of all, I mean, I know it's a European zoo population - so, it may or may not be relevant to U.S. populations - but does this seem possible or reasonable to you? Dr. BOYLE: Well - and first of all, I want to thank NPR Science Friday for delving into this, because it does allow us to identify some of the flaws in the science behind this article. The first thing I want to say is that the term zoo is really misused as a generic term here. There's a wide range of quality of venues that hold animals. So, we represent the best in North America, the accredited zoos that are members of AZA. And those venues of animals range down to roadside menageries, and they exist in all countries of the world.

So, the dataset that was used in this study, if you go to - the sites where the data is - exists range from some of the best zoos through Europe to those roadside menageries. But they've taken of all that data, put it into one bucket, and it's muddled the information in a way that artificially biases the answer of median age to a much lower number.

PALCA: So, you think if the population, for example - and I believe there have been studies out of U.S. zoos that if you look at the, as you called - what does it mean to be an accredited zoo, by the way? How does that qualify - how do you qualify for that? Dr. BOYLE: Well, the AZA, the Association of Zoo and Aquarium accreditation process is the most comprehensive and stringent in the world. It's an incredibly intensive investigation of all aspects of an institution's operation, with significant attention paid to pushing the envelope of animal care and welfare and standards for the keeping of animals. So, you know, we're - another thing that really bothers us about this article is that dataset goes back to 1960s. The data is - goes back 50 years. Now, in one respect, you could say, well, isn't that a wonderful comprehensive study?

But you know, this is kind of like analyzing the success of heart transplants. If you included data back to the 1960s, you know, you would end up with an artificially low number for success, because all fields that depend on science to drive them forward have major advances, especially in the past several decades. So, a specific comment here, you know, when you look at the survivorship, the median age of African elephants in North American accredited zoos, they're - the age is 33 in zoos and it's 33 in the wild.

PALCA: And again, that's looking at a wild population broadly that is exposed to various threats like poaching, I would assume.

Dr. BOYLE: Well, those numbers actually come from the Amboseli population, which is one of the most protected in the world. If you actually include all elephants, the number for median age in the wild goes down significantly because of the rampant poaching that's occurring all over the world. For Asian elephants in North American zoos - this is female elephants - the number is 44.8 years, and the number in the wild is 45 years. So, statistically it's the same. So, what I can speak to is the median-age survivorship of elephants in North American accredited institutions, and it's the same in zoos in North America as it is in the wild for both African and Asian.

Dr. MASON: Can I...

PALCA: I was just going to ask Dr. Mason...

Dr. MASON: Yeah.

PALCA: To - see, I like to - I mean, does Dr. Boyle have a point about the dataset that you were using for comparison in Europe?

Dr. MASON: Not really. He raised three issues. One is that he said our data cover a wide range of zoo qualities, and I absolutely accept that, but I'm not really sure the quality of the average zoo in Europe is really demonstrably worse than that in North America. I mean, it'd be interesting to see some statistics on things like average enclosure size, average herd size and so on to see if that's demonstrably true. But I feel that's a bit of premature claim.

Dr. BOYLE: You're skating across that a little bit because the European elephant...

Dr. MASON: Can I just...

Dr. BOYLE: Web site lists...

PALCA: Right.

Dr. BOYLE: Many that are known to be very, very poor.

PALCA: Right.

Dr. MASON: If I could just finish...

PALCA: Yeah, we have to keep this one at time. Yeah, go ahead.

Dr. MASON: So, we used data from the European stud books, which are animals that are part of the European endangered-species managements plan. So, one issue was the range of zoos; another issue was that we've looked at animals over the past four decades. And basically, we had to do that to build up a large enough sample size to run decent survivorship analyses. But we absolutely take the point that things should have improved in recent years, which is why we looked for that, and we did find optimistic signs in the African elephant, but we didn't find any significant improvement over time for Asian elephants. But we did look for that, because obviously that's a very pertinent question.

His last comment was the average life span in North American zoos he claims his 33 years, and he's getting this from a paper that calculated average life span excluding infant mortality. So, that's kind of cheating. If you exclude a period in which lots of young are dying and just ignore that and then start from year one and calculate an average from there, of course you're going to get a higher value than is true. He's also comparing this average lifespan that excludes infant mortality with figures in Amboseli that include it, which is clearly cheating. You've got to compare like with like here. And that's exactly what we did in our paper; we compared like with like. So, we looked at infant mortality; we compared that across the various populations, juvenile mortality, and adult survivorship, too.

PALCA: OK. Well, I can tell that this is one of those contentious things, because a lot of times when people bring up datasets, the way they look at it and they how parse it can be different. Is it - I mean, I presume that you would be perfectly willing to share the data that you were working from with Dr. Boyle if he wanted to rerun the analysis.

Dr. MASON: Yeah. Absolutely.

PALCA: OK. Well, there's a way possibly forward from that. But let's see what our callers have to say, and let's first go to Amy in St. Marys, Georgia. Amy, welcome to Science Friday.

AMY (Caller): Thank you. Thank you for taking my call. I think that the American Zoological Association ends up on the defensive perhaps more than they need to be, because there are so many people out there, including myself, who really feel tremendously badly about elephants in captivity, most especially elephants used in the circus, but certainly elephants in captivity as well. I know there's been cases well-known to your people there.

Some of the ones that come to mind are the San Diego Wild Animal Park that prides itself on its enclosure for its elephants. And yet, when juveniles are raised in captivity, sometimes there's cases where there's not enough room for them at that enclosure and they end up going to places that I don't think any zoo director worth his salt would want them to. So, I wondered if your guests could explore what happens to juvenile elephants when there's no room at the inn, so to say, of their places of birth? What can we know as citizens will happen to them? Where will they go that we can feel good about?

PALCA: Interesting question. Maybe I could start with you, Dr. Boyle.

Dr. BOYLE: Sure. The first thing I want to point out is that a number of years ago, as with most of what is known about animals, lots of it has come from studies done in zoos. Most what we know about the biology of elephants, in fact, has come from studies done in zoos. And so, 61 of the accredited institutions in North America began or have already completed major expansions. As we have learned about elephant behavior and communication and learned from some of the studies that have gone on, these institutions are pushing the envelope of creating new spaces for the animals in our institutions.

PALCA: We're talking with Paul Boyle from the Association of Zoos and Aquariums and Georgia Mason from the University of Guelph about a study Dr. Mason completed - or just published, I should say - in Science Magazine about the effect of - elephant lifespan for elephants living in zoos. I'm Joe Palca, and this is Talk of the Nation from NPR News. Dr. Mason, did you want to add anything to that?

Dr. MASON: Yeah, just a brief comment. In our analyses, one of the risk factors for early deaths that we found, at least in the Asian species, was actually being transferred between zoos. And we found that each time a female is moved to another site, she has an elevated risk of dying that lasts about four years after that move. And I think it'd be really important to identify why some animals die during this vulnerable period, while other animals are absolutely fine. And one idea that struck me is that animals that are moved from a large, naturalistic enclosure - and obviously, there are some really great looking zoos out there - I wonder if animals that are moved from a large, naturalistic enclosures to smaller ones fare badly, whereas animals that are moved from the smaller, perhaps city-style zoos to large enclosures survive the transfer fine. That's just a hypothesis for future test, really.

Dr. BOYLE: I mean, from a scientific vantage point, it's an interesting question. You could also find the reverse is true.

PALCA: Yeah, I know. But it's something that could be empirically investigated. But let's take another call now and go to Louis in San Mateo, California. Louis, welcome to the program.

LOUIS (Caller): Hi there. Thank you for taking my call.

PALCA: Sure.

LOUIS: When I heard the study yesterday, or heard about it, an idea popped into my head. It just seemed natural that the animals in the zoos would have longevity problems, because when you look at the elephants in the wild, they're moving all the time. And it seems to me that that sedentary life in the zoo would affect their lifespan. I'll take my answer off the air.

PALCA: OK. Thanks, Louis. Dr. Boyle, is there any possibility that it's something as simple as that they just can't move around as much?

Dr. BOYLE: There are differences between the two species. African elephants are known to move great distances, although a lot of that movement can be driven by the search for food and water. It's a known fact that Asian elephants, if food and water are abundant, often don't move much at all. So, do these animals need to walk? Do they need to move? Of course, they do. And that's why our enclosures provide space that's adequate for them to move around and to deal with plant material and so on, and that's why, as we've learned more and more about the science of elephants, our institutions are in a major - and have been for the past five to eight years and will be for the next five to eight years - major improvements in increases in size and space and accommodations for elephants.

PALCA: Interesting. Let's take another call now.

Dr. MASON: Can I comment on the question?

PALCA: Sure. Go ahead.

(Soundbite of laughter)

Dr. MASON: Great. Some data have literally just come out from the UK, actually. They came out yesterday as well.

PALCA: Ah, yes. The DEFRA study.

Dr. MASON: Yeah, absolutely. And here, a scientific team from Bristol University surveyed the entire UK elephant population, and they found that over half of the animals were overweight, but the good news was the degree to which animals were overweight varied a lot between zoos, and it seemed to be less of a problem where you had larger enclosures. Currently, the average enclosure in Europe seems to be about 3,000 square meters, but obviously, there's huge variation.

Almost all of them seem to be under one square kilometer, and even Asian elephants in the wild roam tens of square kilometers. So, there's a big difference in the scope for physical activity. Whether that's really a welfare problem and whether that's really the cause of their possible fatness is obviously an empirical issue. But I'm not sure what the average enclosure size is in North America. I don't know if Mr. Boyle has that figure...

PALCA: Do you have that data with you?

Dr. BOYLE: I don't have it at my fingertips. We can find out.

PALCA: OK. Well, let's see. Let's go to Tom in West Horton, Pennsylvania. Tom, we're going to have to take to a break, but if you can give us a quick question, we maybe can consider it after the break.

TOM (Caller): Sure. I was just wondering, it sounds like the study compared European zoos with African reserves, and I'm wondering if they accounted for the difference in the climates, as far as temperature, humidity, how that could affect longevity.

PALCA: Interesting, because it is a lot colder, I'd say, on average in Europe. Well, that's a question we're going to have leave for after the break, but stay with us because we'll address Tom's question, and we'll hear more about elephants and their lives. Stay with us.

(Soundbite of music)

PALCA: This is Talk of the Nation from NPR News.

(Soundbite of music)

PALCA: From NPR News, this is Talk of the Nation: Science Friday. I'm Joe Palca. We're talking about elephants with Georgia Mason. She's the author of a new study in Science Magazine that compares life expectancies of elephants in European zoos with those in certain wild populations. And also, Paul Boyle. He's a vice president for conservation and education at the Association of Zoos and Aquariums in Silver Spring, Maryland. And we had a call from Tom, who raised the interesting question, I think, about whether the difference in lifespan, which Dr. Mason noted that elephants lived - tended to live a shorter time and there's some question about - there's an argument about whether these data actually are reflective of the true situation. But they are certainly provocative and would make people want to look at the question.

But the question was, can you explain the possibility that animals are living a shorter time in zoos in Europe compared to the wild by simply asking the climate? I mean, you were talking about the UK. It's cold and raw this time of year in the UK. And I'm sure an elephant that was born and evolved to live in the African jungle has got a kind of a different experience.

Dr. MASON: Yeah. It's a really great question. Our data came from over 230 zoos scattered across Europe, Scandinavia and the former U.S.S.R. So, we've got warm zoos in Italy, and Israel and Spain. We've got cold zoos up in the north of Scandinavia. I don't know if there's a systematic difference, but it's a really great question and maybe it's something we should look for. We think - and one possible problem with cold, wet or snowy zoos is that then animals tend to be kept inside for relatively long periods. So, this recent study out of the UK shows that elephants are typically locked in overnight for 10, 12, even more hours each day, which may be a problem. We certainly know that induces stereotypic behavior.

I mean, if I had to boil down the differences between our protected populations in Africa or in Asia where they're living much longer, I'd say one difference is that they're probably more physically fit there. Another difference is that their social groups are more natural in structure; they're more stable; daughters stay with their mothers. And then the other is, of course, the climate. So, how warm it is, how humid it is and also, what kind of vegetation they're eating.

PALCA: Well, Dr. Boyle, I'm going to turn to you, and you're going to have the final word in this segment, I'm afraid, because we've run out of time. But I do want to get your perspective on, you know, whether this study raises questions for you and whether or not, you know, there's just always going to be an issue about animals in a captive situation, trying to compare their lives and their happiness and their life expectancy with those in the wild.

Dr. BOYLE: Well, there's always going to be a question, because there are people out there who just don't want animals to be in captivity, which brings me to the point that I really want to make here, and that is that a point that gets left out of the discussion here completely, and that's about education. You know, Ian Douglas-Hamilton, researcher in Africa, is on record actually in ScienceNOW, I think, as saying this article presents an unrealistic image of elephants in the wild. And he goes on to say that zoos play a significant role in the education of children and adults for conservation.

You know, we have a generation of kids growing up today in the United States - and if you're familiar with the book by Richard Louv called "Last Child in the Woods," there's a 7th grader in Los Angeles who's quoted on the cover leaf there saying, I mostly play indoors because that's where the electrical outlets are. You know, as we urbanize more and more, zoos and aquariums are the windows into nature for the next generation, and that's why these institutions, the accredited zoos and aquariums in North America, serve a population annually of 175 million family groups. That includes 50 million kids, 15 million students. And these institutions are the places where this coming generation is learning what an elephant is.

So, as we look at the rampant poaching that's occurring around the world that's wiping these populations out, and the fragmentation of their habitats that has them on a trajectory towards extinction, these institutions are the places that can save them for the future and especially can educate lots of people about why elephants are important and we should continue to have them on this planet. That's the work of these zoos.

PALCA: There seems to no question that that is the case, but I think, in defense of what Dr. Mason is pointing out in this article, there are issues that need to be addressed, and as noble as the cause is, it's always good to take a good hard look at what you're doing and making sure.

Dr. BOYLE: If I could just add to that by saying we are the ones identifying these issues.

Dr. MASON: Can I possibly interject?

Dr. BOYLE: We are the ones identifying these issues. We are the ones pushing the medical envelope and the nutrition...

PALCA: I hope so. And Dr. Mason, I am apologizing but I really do have to move on to the next subject...


PALCA: On this show, but I appreciate - I think that the point that you're making came across fairly clearly, and I think Dr. Boyle's perspective has been aired as well. So, I'll thank both you for joining me today. Dr. Georgia Mason is a professor and Canada Research Chair in Animal Welfare at the University of Guelph in Ontario. And Paul Boyle is a senior vice president for conservation and education at the Association of Zoos and Aquariums in Silver Spring, Maryland. Thanks to both of you.

Dr. BOYLE: Thanks, Joe.

Dr. MASON: Thanks.

Copyright © 2008 NPR. All rights reserved. Visit our website terms of use and permissions pages at for further information.

NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.