The Impact Of Invasive Bullfrogs On The Demographics Of Northern Leopard Frogs In Northern New Mexico

Presentation: Invasive species are able to alter the dynamics of the trophic levels of an ecosystem and have no natural controls. They can displace native species in the food web, and prey on species with no adaptive defenses. The Rio Mora National Wildlife Refuge has both invasive Bullfrogs and native Northern Leopard Frogs. The purpose of this study is to investigate the effects of the presence of the invasive Bullfrog on the demographics of the native Northern Leopard Frog in northern New Mexico. A section of the Mora River in the refuge was divided into two 2000-meter long section a control site containing Bullfrogs and an experimental site, where Bullfrogs were eradicated. Relative abundance surveys were utilized to sample demographic parameters. Fifty one Leopard Frogs were captured, pit tagged, and processed for demographic data. Six frogs were fitted with radio transmitters. Control and experimental regions did not differ in the relative abundance of Leopard Frogs. We did not find a significant difference in the mass of frogs from the two regions. However, preliminary data does show lower average mass and greater abundance in the experimental region suggesting an increase in recruitment of metamorphosis frog into the population. Telemetry data for four frogs in the control region produced a mean home range size of 531.7 square meters. The Telemetry data shows how frogs can have a large range of sizes in their home range area. Further study of the home range will be conducted to determine if there is a difference in home range between the control and experimental areas.