Blue Iguana Recovery Program

Shedd plays matchmaker with its rare blue iguanas

Aug 2nd, 2002 | By | Category: Blues in the International Press

By Kathy Paur
Tribune staff reporter
Published August 9, 2002

Three blue iguanas at the Shedd Aquarium have emerged as crucial players in a breeding program to save their species–newly designated the most endangered lizard in the world–from extinction.

Only 10 to 25 of the lizards, native to the Caribbean island of Grand Cayman, are alive in the wild, occupying a habitat of about 1 1/2 square miles. About 90 live in captivity.

The fossil record shows the blue iguana–so named for the electric blue color its head assumes during spring mating season–once lived all over the island. But when it was first identified in 1938, its numbers were already quite low after centuries of falling prey to feral cats and dogs introduced by European colonists.

The population was further decimated when Grand Cayman became a tourist destination and the iguanas’ habitat gave way to land development. New roads crisscross the island, and cars are now the biggest killers of blue iguanas, who like to bask on the asphalt in the morning sun.

This summer, a study showed their numbers had fallen so drastically that the blue iguana became the top lizard on the endangered species list. It is estimated that, without expanded captive breeding efforts, the blue iguana will be functionally extinct in five years.

A breeding program has been under way for the last decade at a botanic park on Grand Cayman and at 10 institutions in the United States. But few blue iguanas have been born in captivity thus far because many of the captive iguanas in the U.S. are closely related.

Recently, however, the Shedd Aquarium acquired a suitable male named Marley, and biologists are hoping he will find the aquarium’s females, Eleanor and Cooper, attractive.

To get the lizards’ hormones working, the scientists will provide mood lighting. They also will use mirrors in hopes that Marley’s reflection will stimulate aggressive behavior in Marley and make the females more receptive.

“With a lot of the zoo animals, and aquarium animals, we just try to match them up and give them the best possible conditions . . . do everything right so that they feel in the mood, so to speak,” said Bert Vescolani, Shedd’s vice president of aquarium collections and education.

Since losing their display habitat to the Shedd’s “Amazon Rising” exhibit, the iguanas have been living in a warm and humid private room, sunning themselves atop individual concrete mounds under artificial lights.

The lizards grow to about 5 feet long and have an estimated life span of 80 years.

As part of the breeding program, biologists perform genetic tests on the captive iguanas and keep “stud books” detailing how the population is interrelated. They try to breed pairs to preserve as much genetic diversity as possible and aim for a captive population of 225 lizards.

That will be many more than now exist in the wild. This summer Fred Burton, director of the Blue Iguana Conservation Program on Grand Cayman, and several other conservation biologists spent months tracking wild blue iguanas in all the locations where they had been known in 1993, when they numbered 150.

The researchers followed the iguanas through scrub and cactus over a terrain of daggerlike rocks, using aerial photos that showed sunny spots ideal for basking and tracking the distinctive dung piles the lizards leave behind.

“The whole situation began to look more and more depressing,” said Burton. “We found that half the land that was occupied by iguanas is no longer occupied by iguanas, and within the remaining half of the area, the population density had plummeted to a fifth of what it was. So the best guess for the total number of wild iguanas is between 10 and 25 individuals. That’s all.”

“So you can imagine that was a serious shock.”

Following the blue iguana’s elevation to the most endangered lizard in the world, the International Iguana Foundation is campaigning for funds to save it. According to Rick Hudson, who coordinates the U.S. breeding program, it would take as little as $150,000 to guarantee the lizard’s survival.

“A donor’s legacy could be that they saved a species personally,” said Hudson, a conservation biologist at the Ft. Worth Zoo. “Reptile conservation doesn’t take that much. You can throw millions of dollars at rhinos and elephants and pandas and barely make an impact, whereas $150,000 for an iguana–you can save a species.”

Copyright © 2002, Chicago Tribune

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