Unlocking Nutritional Secrets

Gray’s Monitor Lizard Conservation

In April this year I traveled to the Philippines to conduct a conservation project for one of the world’s most unusual and least-understood reptiles, the Gray’s monitor lizard or ‘Butaan’ as it is locally known. Serving as Principle Investigator for a joint project that brought together two North American zoos (Virginia Zoo and Oklahoma City Zoo), in partnership with the University of the Philippines and the Polillo Island Biodiversity Conservation Foundation. Our goal was to collect samples of the wild foods eaten by this lizard to perform nutritional analysis to better understand the biology of these threatened animals and to provide a better diet for them in zoological collections.

Gray’s monitor lizards are unusual compared to most other species of Monitor lizards that are almost entirely carnivorous, while the Gray’s Monitor Lizard has evolved to be almost entirely frugivorous when adult. It is known to feed of the fruits are various wild trees in the Philippines and is one of the most secretive members of the Monitor family of lizards. Grey’s Monitors are currently only kept at the Oklahoma City Zoo and the Los Angeles Zoo in North America. They have proved difficult to keep healthy, not adapting well to the types of fruits and vegetables available in North America.

Funded with the support of a Conservation Action Now grant from the Oklahoma City Zoo, I arrived in the Philippines on April 5th and then quickly headed to the Laguna campus of the University of the Philippines. I spent a couple of days at the University coordinating with our collaborators there and checking that the nutritional analysis lab was prepared for the arrival of field samples the following week. From the University in Laguna I headed to the East coast of Luzon and the port of Infanta to catch an early morning ferry to the island of Polillo. After a 3 hour sea crossing I arrived on the island to be greeted by members of the Polillo Islands Biodiversity Conservation Foundation (PIBCF). As local partners in this project PIBCF arranged for the permits to allow field research and sample collection from a reserve area and also arranged for pre-project meetings with the local mayor & chief of police before we could head into the protected area.

Our field project site was the Sibulan Watershed Reserve about 10km inland from the port where I spent 5 days surveying the forest for our target tree species. We know what fruits these animals eat in the wild from previous research looking at what seeds are present in scat samples, what we didn’t know is the nutritional content of those fruits that are very unlike anything we typically used in diets. We spent three days surveying trees of the target species that had fruit and then assessed which of those trees had fruit in the most appropriate developmental stage. On the fifth day we collected samples immediately before leaving the watershed reserve and headed back to the port. Then it was a race to keep the samples cool and in good condition while getting back to the University as swiftly as possible.

The results are now being compared to the fruits and vegetables that currently are offered in zoo diets.

Roger Sweeney, Assistant Director Virginia Zoo

Photo Credit: Gray’s Monitor Lizard at Los Angeles Zoo, Ian Recchio