Thursday, April 21, 2011

Penguin Family Trees - Rooted in Science

One of the first questions Tennessee Aquarium visitors ask at Penguins' Rock is, "What are the penguins wearing?" Our docents usually begin by giving the short answer, "Flipper bands that help our aviculturists quickly identify individual birds." Often they go on to explain that for acute care, like if a penguin was observed favoring a foot, these bands help them locate that individual bird quickly for a closer examination.

For longer term care, flipper bands help keepers track each penguin's health history and family lineage. By recording the "genealogy" of each individual, aviculturists can ensure that related birds don't breed.

Animal husbandry, like any science, continues to grow as knowledge is added through research and experience. The Association of Zoos and Aquariums, AZA, has been leading the way in animal management programs for years. This collaboration of scientists has developed Species Survival Plans for all types of animals, including penguins. In some cases, drastic measures are needed. For example, some amphibians are so critically endangered in the wild, the only way to stop extinction is to bring the remaining few into captive breeding programs in hopes of saving the last animals from vanishing forever.

Fortunately that's not the case with most species seen at zoos and aquariums. However, AZA recognizes that for the long-term future of animal care, healthy and genetically diverse populations are needed. This will sustain the number of animal ambassadors and reduce the need for animals to be collected in the wild. And, these breeding programs work. If it weren't for a well-managed penguin program at SeaWorld, we wouldn't have a robust collection of gentoo and macaroni penguins in Chattanooga.

The Tennessee Aquarium is an AZA-accredited institution and we recognize the importance of this long-term sustainability strategy. Many of these new recommendations are being implemented now. Which brings us to this year's breeding plan.

After carefully examining the family trees of our birds and checking with the AZA penguin experts in charge of the gentoo and macaroni management plan, it was discovered there were only a few of our birds that have the genetic diversity best suited for long-term sustainability.

So with a few exceptions, any eggs produced this year will be replaced with artificial eggs much as we have done the past two years when eggs would get cracked in the nest or were infertile. By replacing the penguin eggs with replicas, the pairs still have the opportunity to engage in natural behaviors without interrupting other pairs in the colony. Whether an artificial egg or infertile egg, penguins will only stay on the roost for a certain amount of time and then move on. This behavior is the same on exhibit or within gentoo and macaroni colonies in the sub-Antarctic.

It's important to remember that many of our penguins are still relatively young and have collectively only produced one chick each season out of dozens of infertile eggs laid. "Pepper," a macaroni chick in 2009 and "Shivers," a gentoo chick last year.

At this point "Biscuit" and "Blue," the gentoo parents that successfully raised "Shivers" last year, are the only pair that meet the needs of the this year’s plan. So we'll wait to see if they add to their family tree this year.

We hope everyone understands that truly caring for animals involves much more than providing proper nutrition, suitable habitat and expert veterinary care. These animals also deserve well-planned breeding management that preserves healthy populations for generations.

Senior aviculturist Amy Graves holding one replica egg and one real egg.

Which is which? Both are roughly the same weight and have the same shell texture.
The left egg, marked with a red dot, is an eagle egg replica. "They are the same size and weight as a large macaroni egg or small gentoo egg," Graves said.

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