Lizards of Guatemala

A large male Guatemalan beaded lizard relaxes in one of the outdoor breeding pens.

I was recently in Guatemala for the 15th annual meeting of the International Union for the Conservation of Nature (IUCN) Iguana Specialist Group (ISG). Thank goodness for acronyms! As the name implies, the group is focused on the conservation and preservation of iguanas. These large, herbivorous lizards are found throughout much of the New World’s tropics and subtropics. Many iguana species are threatened with extinction due to hunting (apparently they taste like chicken), habitat loss associated with agriculture and development, introduced predators, road kills, and other human-associated threats.

Part of the meeting included a workshop focused on local iguana species, one of which occurs in Guatemala’s Montagua Valley. After the meeting and workshop, the group took a field trip to this valley to see these iguanas and to visit the conservation-breeding program for one of Guatemala’s other rare and endemic species, the Guatemalan beaded lizard, a close relative of the Gila monster found in the deserts of the American Southwest.

Thanks to the efforts of local conservationists, the future for both the iguanas and beaded lizards of the Montagua Valley is looking brighter.

Glenn Gerber is head of the San Diego Zoo’s Caribbean Regional Program. Read his previous post, Iguanas: Why Move?


Iguanas: Why Move?

Turks & Caicos iguana

Late 2011 marked the first in a series of experimental iguana translocations on Big Ambergris Cay in the Caribbean’s Turks & Caicos designed to determine the conservation value of moving these large, endangered lizards out of areas slated for development to areas on the island that will not be developed. At first glance you may find it difficult to question the value of moving animals like this. Then again, why wouldn’t you move animals out of the bulldozer’s path? Well, what if the translocated animals simply return home? Or what if their survival in their new habitat is very low? Both of these outcomes are actually quite possible.

Iguanas are territorial animals with small home ranges, and they live a long time. They know their territories well and have invested a lot of time and energy establishing themselves in these areas. This means that animals moved away from their home areas may be highly motivated to return. It also means that iguanas moved to a new area may find they are not welcome by the iguanas already living in that area.

To test these ideas, we moved adult and juvenile animals of both sexes and attached radio transmitters to them to follow what they did. Five out of 12 adults moved (3 males, 2 females) successfully returned to their home areas, and all of those that didn’t return home had tried to. All of the adults moved also lost weight, an indication that they were stressed by the move.

In contrast, none of the 12 juveniles moved returned home, although some did make movements in that direction. The juveniles also lost less weight than the adults, suggesting they may be better candidates for such translocations. To determine if these conclusions are valid, we will need to repeat this experiment to increase our sample sizes. In the end, we will be able to implement a conservation management strategy that makes the best use of limited resources and has the best probability for success.

Glenn Gerber is head of the San Diego Zoo’s Caribbean Regional Program. Read his previous post, Turks Island Boas.


A Significant Blue Birth

The San Diego Zoo’s Applied Animal Ecology Division is pleased to announce the hatching of a critically endangered Grand Cayman blue iguana Cyclura lewisi. This little female iguana hatched out of her egg on September 13, 2008, after an incubation of 92 days at 86.5 degrees Fahrenheit (30.3 degrees Celsius). She weighed only 1.58 ounces (45 grams) at hatching—a tiny little girl compared to males of her species that can grow to over 18 pounds (8 kilograms) as adults! Although our little girl is gray in color now, as most hatchlings are, adults of the species can become a beautiful powder blue color.

This iguana was a very lucky animal. About three-quarters of the way through incubation, her egg formed a small crack and started to leak fluid. This is a rare occurrence and can be caused by too much humidity, a thin shell, or many other factors. I patched the shell with plastic wrap and tissue glue and crossed my fingers. A few weeks later, I got the word that the iguana had hatched, and I ran over to the incubator room to see her. She looked good, although she had a distended belly, which usually means she hatched a bit too early and wasn’t able to absorb all of her yolk. I took her to the vets at the Harter Veterinary Medical Center, and due to the distended belly and a slight injury to the eye that probably happened during hatching, we decided she would stay with the vets. Internal yolk can usually absorb on its own as long as the animal is kept quiet and warm, but sometimes it can become infected and can even be lethal. After a week of excellent veterinary TLC, the little iguana absorbed her yolk, and her eye was healed up. She is currently waiting to be housed in the new iguana building that is near completion in an off-display area of the Wild Animal Park (stay tuned for that blog!).

Grand Cayman iguanas are considered to be the most endangered lizard in the world. Loss of habitat, introduced predators, feral animals that compete for resources, and cars all contribute to the iguana’s decline. At one point, there were as few as 20 animals left on Grand Cayman, but thanks to captive breeding, headstart and release protocols, and a new reserve system on the island, Grand Cayman iguanas are slowly starting to repopulate the wild.

Jeff Lemm is a research coordinator for the San Diego Zoo. Read Jeff’s previous blog, Frog Blog—What’s Hoppenin’?