TORONTO, ON, Wednesday, August 14, 2019: Toronto Zoo is proud to be the home of some of the most critically endangered amphibians in North America. The habitat of many of these species has been so drastically changed by humans that they now only live in small isolated populations, some having an estimated wild population of just 100 frogs. With the support of many partners, zoos across North America have initiated conservation breeding programs for several of the most threatened species in the hopes of releasing them back to restored habitats in the wild. Toronto Zoo recently sent 36 dusky gopher frogs that were born and raised at the Zoo to Memphis for release into the wild.
For several years the Toronto Zoo has participated in Species Survival Plan (SSP) breeding programs for the critically endangered dusky gopher frog (Lithobates sevosus), also commonly known as the Mississippi gopher frog. This specific North American species of frog is notoriously difficult to breed outside of their natural habitat. In the wild, the frogs go through a winter hibernation period until the spring rain and rising temperatures signal them to awaken and start breeding. At the Toronto Zoo, we endeavor to mimic the specific environmental cues required to encourage natural breeding, but the Zoo’s initial attempts were not successful.
In the fall of 2017, the Zoo’s Amphibian and Reptile Curatorial staff and Reproductive Physiology team worked together to overcome the challenges of natural breeding in the dusky gopher frog by applying Assisted Reproductive Technologies (ART). Using techniques originally developed by amphibian researcher, Dr. Andy Kouba, at Mississippi State University, a subset of adult frogs underwent a series of hormone injections prior to the collection of eggs or sperm that were combined together in a petri dish for artificial fertilization. Within hours the team witnessed the first dusky gopher frog embryos ever to develop in Canada. Over the next several months Zoo staff watched the embryos develop into tadpoles and metamorphose into juvenile frogs, which were ultimately be released into the wilds of southern Mississippi this summer.
When this program first began in October 2014 the dusky gopher frogs’ habitat could be found at one of the Toronto Zoo’s specialized conservation breeding centres along Meadowvale Road. Shortly after it was opened in June 2017, the dusky gopher frogs were moved to the Zoo’s new Wildlife Health Centre. Due to the sensitive nature of the dusky gopher frogs, their habitat is located in a quarantined area of the Zoo and not on public display.