Southwest Environment

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Department of Soil, Water and Environmental Science
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Tucson zoo hopes to breed tiger under Species Survival Plan

By: Jessica McGlynn
tiger exhibit at Reid Part Zoo
Photo by Jessica McGlynn
A young girl leans down for a closer look at the Reid Park Zoo's tiger exhibit.

Baheem, a Malayan tiger at Reid Park Zoo, rests under the shade of the green foliage lining his enclosure as the beating sun continues to heat up the Tucson afternoon. Turning his head every now and then to gaze behind him at wide-eyed children and camera flashes, the tiger lounges alone in his habitat.  Baheem will not be alone for long, however, as the zoo is expecting a special delivery from New York’s Bronx Zoo in upcoming weeks.

The Reid Park Zoo is planning to introduce nine-year-old Baheem to a new female Malayan tiger in the hope of encouraging reproduction between the two.  This captive breeding is an increasingly popular technique for restoring and maintaining endangered species like the tiger.  Reid Park Zoo hopes to incorporate captive breeding among other animals as well in the near future.

“We are going to try and be more involved with breeding down the road,” said Jim Schnormeier, the general curator at the Reid Park Zoo.  The new elephant facility that is now in progress will be used for breeding African elephants, Schnormeier explained.  The zoo also recently received a male lion to pair with its female, and a female Baird’s tapir is also expected to join the zoo’s male.

Each of these breeding suggestions was made under the Species Survival Plan.  The SSP, a program with the Association of Zoos and Aquariums, was established in 1982.  Today it includes more than 200 certified facilities.

One of the primary objectives of the SSP is working to keep diversity in the genetic pool of animals involved in captive breeding programs. Melanie Culver, a Natural Resources assistant professor at the University of Arizona, explained the importance of genetic diversity in captive-bred populations and the correlation between diversity and species’ fitness.  Fitness is the reproductive success of a genotype, which is measured by how many surviving offspring are produced. 

“Low diversity,” Culver said, “means lowering of fitness, and higher genetic diversity means the population has much more potential to have higher fitness.”

In order to maintain genetic diversity in captive populations, the SSP has a coordinator for each species involved who, along with other members, examines heritages and genetic information before deciding which animals are genetically diverse enough to breed. 

Nowadays, if it is impossible to identify where a big cat came from, SSP coordinators will not choose it for breeding. Before the SSP, Schnormeier explained, the genetic pool was becoming murky.  When a small number of animals breed too often, it can lower genetic variation, which is important for species health and survival. 

Before the plan was developed, zookeepers were promoting crossbreeding and inbreeding in some cases to come up with novelties such as the white tiger. Although attractive, the white tiger has reduced genetic diversity, which can make it more susceptible to disease and other problems. (For more on this, see related story.) The SSP works to avoid such efforts by trying to tighten up the requirements for breeding and thus regain genetic diversity, a premium goal for modern zoos.

The SSP also works to take into consideration the amount of space that zoos have available.

“Space is a premium and is very much a driving force as much as the genetics,” Schnormeier said.  SSP coordinators consider the current numbers of the animals in zoos and the space available in the facilities in order to decide if reproduction should take place, and to what degree.Tiger named Baheem at zooPhoto by Jessica McGlynn
Baheem rests near the fence of his enclosure at Tucson's Reid Park Zoo where he will soon be taking part in one of the zoo's latest captive breeding efforts.

Match-making efforts, despite the best of intentions, do not always work out. SSP tiger coordinator Ron Tilson initiated six breeding recommendations last year for the Malayan tiger, one of several subspecies of tiger (Panthera tigris).  So far, only one of these recommendations resulted in a litter, producing three surviving cubs of this subspecies, also known as the Indochinese tiger.  According to information shared by Tilson, there are 47 actively managed Malayan tigers in North America as of 2010 and about 1,100 total tigers in captivity. For more information view the fact sheet


from the Nutrition Advisory Group website (http://www.nagonline.net)

The tiger in particular has become an icon to the public on behalf of the plight of endangered species and the drive for conservation. 

“Tigers are probably one of the older SSPs and probably one of the strongest,” said Schnormeier. “Tigers are very high-profile animals. They have a lot of people involved with the field work and they also have pretty good funding for different projects.”

The World Wildlife Fund, for instance, has a Tigers Alive Initiative that focuses on conserving large areas of suitable habitat where a significant portion of the wild tiger population can be found, explained Jamie Kemsey, the initiative’s communications manager.

Although captive breeding programs may keep a species from extinction, habitat loss and human interaction difficulties can prevent a species from ever being successfully reintroduced.

“In order for tigers to not only survive but thrive, they need large landscapes, and WWF focuses on conservation of these landscapes,” explained Kemsey. 

Currently, captive-bred tigers are not being reintroduced to the wild because of the lack of sufficient habitat and effective government protection of the species, Schnormeier said.

However, Culver explained that if tigers are going to be reintroduced at any point, SSP coordinators must consider the genes that will allow the species to thrive in the wild and work to preserve these traits, not just those that will do best in captivity. See related story.

In order for reintroductions to be successful, several issues must be addressed.  Kemsey mentioned one of the primary reasons for tiger endangerment is the trade of tigers and tiger parts.  Poaching of tigers for bones and organs for supposed medicinal purposes is a common practice, Kemsey said.

Another primary reason for tiger endangerment is the loss of habitat and, in turn, prey.

“The final factor is human-tiger conflict.  As (human) populations rise, tigers are increasingly coming into contact with humans,” he explained, “Hungry tigers attack livestock, and sometimes even humans, and human retaliation is often swift: the tiger is often hunted and killed or poisoned.”

The controversy continues to grow as human population expands, habitat loss progresses and tigers become ever closer to extinction. Still, Schnormeier and Culver consider it important to keep the species viable as a back-up population to ensure the continued survival of the tiger population and, if the need and opportunity arises, to reintroduce them into the wild.

“Tigers have lost 97 percent of their population since the turn of the 20th century, going from approximately 100,000 in 1900 to only 3,200 today,” said Kemsey, “Tiger conservation is a complex issue dealing with a complex species.”


Jessica McGlynn is a Wildlife Conservation major whose primary interests include endangered species and captive breeding.


RELATED LINKS

Related story by Jessica McGlynn
Like mother, like daughter: Captive breeding efforts consider genetic diversity

Species Survival Plan
http://www.aza.org/species-survival-plan-program/

World Wildlife Fund’s Tigers Alive Initiative
http://www.worldwildlife.org/species/finder/tigers/index.html

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