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Photo of Benjamin Beck Benjamin Beck
Return to the Wild

Benjamin Beck, Associate Director for Biological Programs at the National Zoo in Washington, specializes in reintroducing animals to the wild by teaching them survival skills such as how to search for food. What's it like to run the "jungle boot camp" we see on The New Zoos? Check out these questions and answers for a firsthand report.

q The show said that most of the golden lion tamarins now in the wild are descendants of animals born in zoos. Do you know if the golden lion tamarins born in the wild have enough genetic diversity to establish a successful self-sustaining population?

A Our computer models suggest that there is enough genetic diversity among the descendants of the reintroduced golden lion tamarins to be self-sustaining. The zoo population has been managed to maintain as much genetic diversity as possible, and we select tamarins to send to Brazil in part on the basis of genetic diversity. There will even be more diversity when the descendants of reintroduced tamarins begin to mate more frequently with the truly wild population. We have tried to keep these two populations reproductively separate (to make sure that there was no disease threat to the wild population), but there have been several matings anyway. We anticipate more in the future. We are now trying to grow "bridges" of forest between the separate forest patches occupied by the tamarins. They will then be able to mix more easily.

q How do you know when it's time to return the animals back to the wild?

A Before we ship the tamarins to Brazil, we give them a complete physical examination to make sure they are free of any disease, injury or genetic defect. After they arrive in Brazil, we give them a few days in a cage in the forest to recover from the fatigue and dehydration of the long flight, and to get used to their surroundings. If they appear normal, we reintroduce them. We would not ship or reintroduce a pair with very young infants, or if the female were late in a pregnancy. Otherwise, there are no set criteria.

q Is there a difference in size or colors of the fur for male and female tamarins?

A No. Golden lion tamarins are sexually monormorphic, meaning that males and females are about the same body weight and don't differ in external body characteristics. Can you think of a species that is sexually dimporphic, that is where males and females differ in body weight and external characteristics? (Hint: look around you) Can you think of another monomorphic species?

q Do tamarins mate for life? And how many babies do they have at a time?

A At any one time in a group of tamarins there is only one reproductive male and one reproductive female. Thus they are said to be monogamous. But if one dies, the survivor takes a new mate within a day or two. There is no sign of loss or sadness that we humans have been able to perceive. A female normally gives birth to twins (fraternal, not identical). Often only one survives but usually both do. Fathers and older siblings help to carry the twins, and when the infants are older they give them solid food.

q How successful is the effort to get Brazilian ranchers to set aside forest land for habitats for the golden lion tamarins?

A At present, ranchers have committed about 2,900 hectares for informal protection as a result of the reintroduction program. Considering that the main reserve for the golden lion tamarin is only 5,000 hectares, this is a very significant addition. Computer models suggest that we need about 20,000 hectares of forest to sustain a wild population of about 2,000 tamarins, and that a population of 2,000 would survive. We currently have about 800 tamarins on 8,000 hectares, well on the way to saving this species from extinction. And don't forget that we are also saving all of the other animals and plants that live in the forest. We and our Brazilian partners are trying to save an ecosystem! Many Americans are trying to reserve some of their own land as natural habitat; even a brush pile in the back yard makes a bit of bird habitat.

q Now that you have found the program you've been running really has not made that much difference to the monkeys' eventual survival, are you going to disband it and just teach them in the real environment in Brazil?

A You are correct that allowing the tamarins to range freely in forests on the Zoo grounds does not confer an increase in their post-reintroduction survival. But it does have a powerful educational impact on our 2,500,000 annual visitors, and we can use the tamarins to present lots of good information on biology and conservation. Thus we will continue to have free-ranging exhibits in about six zoos in the United States. What's the nearest zoo to you to have a free-ranging golden lion tamarin exhibit?

q How did the golden lion tamarins get to be endangered in the first place?

A European settlers cut the forest on an unprecedented scale to send timber back to Europe and to clear the land for agriculture (mainly sugar and coffee at first and now cattle and citrus). When the forest is cut, all of the animals are threatened. The tamarins had an additional threat, since they are so beautiful: they were captured for the pet trade both within Brazil and internationally. Some still get stolen occasionally for the pet trade but this threat is largely removed. However it takes vigilance and cooperation to keep the rest of the forest from being cut. The Brazilian government and citizens are doing a good job of trying to eliminate these threats. Do you see any similarities in the way Europeans settled the United States, and in the way we use our natural resources today.

q You said that one of animals was having trouble with locomotion and getting around because it had grown up in a cage. Why don't the zoos where the animals grow up keep them in a non-caged environment like you have at the National Zoo?

A First, we are not sure it would make much of a difference. It seems that the only place they can really learn about living in the wild is in the wild (at least we haven't yet found a way to help prepare them while they are in the zoo). Second, it takes a lot of people to monitor the tamarins when they are in the non-caged environment so we'll be able to get help quickly if they get in trouble. We don't have enough staff and volunteers to do this all year round. Finally, it gets too cold outside in most places in the United States to leave them outside all year. I have a question for you: do you prefer the non-caged environment because it may help prepare tamarins for life in the wild, or because you prefer seeing them in a natural tree rather than in a cage? Which do you think they prefer?

q Have you ever considered cloning as a possible solution to the diminishing population of golden lion tamarins?

A Cloning is unlikely to be a useful conservation tool because it does not preserve genetic diversity. Genetic diversity or genetic variability is crucial to the evolutionary process because it provides a genetic basis for adaptation to changing environmental conditions. Also, low genetic variability (often due to inbreeding) has been directly linked to decreased survivorship, reproductive problems and other deleterious characteristics. Since cloning produces genetically identical organisms, variability is lost. This is OK for producing large numbers of animals for commercial use, but of far less value (maybe only a desperate last step) for conservation.

q At the end of the show you talked about the revolution that's occurred with zoos over the past 25 years. How do you envision the role of the "new zoos" over the next quarter century and into the future?

A I can't restate this more clearly than the last three minutes of "The New Zoo": zoos will be (are becoming) conservation organizations. They will promote conservation through public education, scientific research, professional training, and the development of animal management techniques. Money raised by zoos will increasingly be used to fund conservation projects in the wild. The chief challenge for zoos will be to stay relevant, so that people will want to come (and pay) to see real animals rather than watch them on TV or the internet, or read about them.

q How can I become involved in helping with these breeding programs or the research being conducted? And is there a way to become involved in these programs outside of being the direct caretakers of the animals?

A Many zoos have volunteer programs. The National Zoo (through the Friends of the National Zoo) enlists and trains volunteers who help with public education and animal care. Don't expect to get up close and personal with animals, and expect to have to make a substantial commitment of time. Expect to be trained and be prepared to make a real commitment to high standards of animal care or informational accuracy. Many would-be volunteers are not ready for these expectations.

The other avenue, of course, is to pursue graduate work in wildlife management, zoology, veterinary sciences or other fields/subfields, and devote your professional life to conservation programs.

q Dear Dr. Beck, I am the educational director for Texas Wildlife Rehabilitation Coalition. We are an organization of volunteers who have state and federal permits for rehabbing native Texas and migratory wildlife. We are based in Houston and are the only urban wildlife rehab group to be certified by the International Wildlife Rehab. Coal. I've found that we have become very medical in our approach and work closely with a veterinarian. The traditional mandates for preventing imprinting are strictly adhered to, but I am not certain we have a sufficiently broad perspective on captive habitats. The state and federal regulations certainly control many aspects of what we do, but our rehab candidates live in clean cages and eat out of bowls for the most part. I am ordering a copy of the New Zoos for our May educational program. I have not been able to locate resources specific to native Texas wildlife and migratory songbirds that would help us adapt our conditioning cages and methods of giving care, especially to the huge population of orphaned newborns or hatchlings we take in annually and successfully release. Do you have recommendations or references I can tap into? Even our national organization has limited resources on this topic. We would like to begin making training videos to help us teach new volunteers, but I want to include appropriate habitat adaptations and rehabber behavior skills before we commit it to film. I appreciate you taking the time to consider this query. Thank-you!

A First, don't discount your emphasis on medical issues. Responsible rehabbers as you doubtlessly know do not want to release animals that are ill or injured and thus are unlikely to survive. Conservation-based reintroduction has the additional concern of not wanting to introduce a communicable disease into the wild.

Training or preparation for reintroduction is quite controversial at the moment. As I said in The New Zoo, there is a strongly intuitive notion that training will increase the chances of post-release survivorship. But there are virtually no data to support that position. It seems that intense post-release monitoring and support has more to do with success than any type of pre-release training. Do you systematically monitor the outcomes of your rehab/release efforts?

q McKelvie Middle School, Bedford, NH, students will be conducting the activity "If I ran the zoo." We are in need of information regarding animals, and their recommended habitat size. We have searched the internet addresses with no luck on this data. Please address.

A The US Department of Agriculture sets enclosure minima for mammals. Each wild golden lion tamarin needs about 10 hectares of good forest to survive, hence 2000 tamarins need 20,000 hectares, and they should be contiguous for good gene flow. I suggest you get a copy of the Animal Welfare Act to find the enclosure minima.


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