The Puerto Rican Crested Toad is the only native toad in Puerto Rico. Known for its distinctive upturned snout and bony head crest, it was previously thought to be extinct until rediscovery in the 1960’s. Today, the Puerto Rican Crested Toad is critically endangered with only one remaining wild population in the Guanica National Forest in the southern part of the island. Its biggest threats are habitat loss brought on by an increase in the human population, and the introduction of non-native predators and non-native invasive species, such as the Cane toad.
In an effort to save the Puerto Rican Crested Toad from extinction, the Association of Zoos and Aquariums (AZA) created a Species Survival Plan (SSP) focused on research, habitat protection, citizen education and outreach, and a viable reintroduction program. Through the SSP, AZA institutions have sent more than 250,000 tadpoles bred at zoos and aquariums in North America to be reintroduced into the wild. The reintroduction program is the perfect example of in-situ conservation and how Zoos can directly impact species propagation around the world. The Puerto Rican Crested Toads held at the Zoo for the breeding and release program are held off exhibit, in a biosecure area, far away from the rest of our herpetology collection, so that no exotic pathogens will be introduced when the tadpoles are released in Puerto Rico.
Nashville Zoo’s Work
Nashville Zoo has been working to breed the Puerto Rican Crested Toad since acquiring the species in 2008, but was not successful until 2012 with the introduction of a hormone cocktail called Amphiplex. The Zoo had previously used the same hormone preparation, developed by Vance Trudeau, University Research Chair in Neuroendocrinology at the Centre for Advanced Research in Environmental Genomics at the University of Ottawa in Ontario, to successfully breed hellbenders using artificial fertilization. Thanks to the addition of Amphiplex, Nashville Zoo has produced 10,365 tadpoles that have been shipped to Puerto Rico for release. In addition to the Amphiplex, our skilled amphibian expert, Sherri Reinsch, has maintained the toads in good health which is also required for successful reproduction in captivity.
Shipping tadpoles to Puerto Rico is a coordinated effort of all participating institutions. All institutions that are attempting to breed Puerto Rican Crested Toads follow the same protocols, so tadpoles are “born” at the same time and are around the same size at release.
The process begins by cooling adult toads to 66 degrees for about two weeks, then warming them to 82 degrees. They are then given a precautionary antifungal soak before being placed in a rain chamber. If they have not laid eggs after three days, Zoo staff administers the Amphiplex hormone cocktail.
When given the go-ahead from the SSP Coordinator to ship, the tadpoles are placed in large plastic bags with water and added oxygen. The plastic bags are placed in large Styrofoam boxes to avoid extreme temperature fluctuations in airline cargo compartments. Shipments are coordinated and picked up by the Caribbean Ecological Services Field Office, a division of the US Fish and Wildlife Service. All the bags are taken to the release site where they are placed in the pond and water is slowly added to acclimate the tadpoles before they are all released. Upon release, the tadpoles are monitored by the USFWS and the Puerto Rico Department of Natural and Environmental Resources (DNER) until they metamorphosed and disperse from the release pond.
Latest News from Nashville Zoo
Nashville Zoo, Toronto Zoo and San Antonio Zoo sent 5,742 tadpoles to Gabia in May 2014. Of these 5,742 tadpoles, 4,492 were sent from Nashville Zoo. The tadpoles were successfully released in a pond (left image) surrounded by a protective structure (funded by the SSP) built to keep out predators. In addition to the US and Puerto Rican wildlife agencies, local school children participated in the release as part of the ongoing initiative to educate the local citizens on Puerto Rican crested toad conservation.
Adult Puerto Rican Crested Toads can be seen in the Unseen New World as part of the Amphibians in Crisis exhibits.