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NISAW Webinar: American Bullfrog Management to Support Conservation and Recovery of Native Species in the West

February 24, 2023 @ 1:00 pm 2:30 pm CST

American bullfrogs (Lithobates catesbeianus) are not native to western North America and threaten dozens of Species of Greatest Conservation Need and many federally Threatened or Endangered species. Control or eradication of American bullfrogs may seem impossible. However, a handful of success stories demonstrate that control is possible and benefits native frogs.

Yosemite National Park in California, known for breathtaking waterfalls and meadows, houses a unique assemblage of aquatic species. Bullfrogs introduced in the 1950s contributed to their decline, including native frog extirpations. Park biologists removed bullfrogs in Yosemite Valley from 2005-2019, achieving eradication and allowing the subsequent establishment of a California red-legged frog (Rana draytonii; federally Threatened) population there. The park is completing bullfrog removals at 2 more park sites (with red-legged frog re-introductions starting in 2023), collaborating with partners to eliminate bullfrogs outside Yosemite, and monitoring annually to prevent bullfrog re-establishment. 

In Arizona, the federally threatened Chiricahua leopard frog (Lithobates chiricahuensis) declined by as much as 80% at the time of listing in 2002, primarily due to predation by bullfrogs, disease, and habitat degradation. Bullfrog control and other actions in the Recovery Plan have resulted in a three-fold increase in occupied sites, functioning metapopulations, and control of bullfrogs in key areas. Ongoing work includes continued bullfrog removal, maintenance of “buffer zones” designed to limit recolonization, and research on amphibian disease dynamics in the wake of bullfrogs. In northwestern Arizona, conservation partners recently released the relict leopard frog (L. onca; SGCN in Arizona, Utah, and Nevada) into a Mojave Desert spring that was occupied by bullfrogs until a long-term, multi-agency project successfully removed the last bullfrog in 2019. 

The U.S. Fish and Wildlife Service is working with partners to build on these stories, communicating invasive bullfrog impacts, highlighting opportunities for control, and providing support for expanded American bullfrog control efforts to conserve and recover at-risk and listed species in the West.


Presented by Matt Grabau, U.S. Fish and Wildlife Service, Ninette Daniele, Yosemite National Park, and Audrey Owens, Arizona Game and Fish Department

Matt Grabau is the Arizona and New Mexico At-Risk Species Coordinator for the U.S. Fish and Wildlife Service. Matt worked on various riparian restoration projects along the Colorado River in Arizona, California, and northern Mexico for ten years before he began working with USFWS in 2016. In his current role, Matt facilitates partnerships to identify research and landscape-scale conservation needs for at-risk species in the Southwest and beyond. Matt is also the Chair of the National Conference on Ecosystem Restoration. He received his undergraduate degree in Wildlife Science and Masters and PhD in Agricultural and Biosystems Engineering at the University of Arizona.

Ninette Daniele is a Wildlife Biologist at Yosemite National Park. She has worked there since 2008 on studying and conserving native wildlife, including the Yosemite toad, Sierra Nevada yellow-legged frog, and Northwestern pond turtle. Much of this work has included an invasive species abatement component. She earned an M.S. at California State University Chico, where she studied blood chemistry in Western pond turtles. She received undergraduate degrees in at California Polytechnic State University San Luis Obispo. In her spare time, she can be found camping and mushroom hunting with her family and dogs.

Audrey Owens is the Ranid Frogs Project Coordinator at the Arizona Game and Fish Department, where she has worked since 2007. The Ranid Frogs Project manages and supports Arizona’s six native ranid species through a partnership community that includes the U.S. Fish and Wildlife Service and other federal, state, university, and private entities. She received her Bachelor of Science degree in Wildlife Ecology and Conservation from University of Florida, and a Master of Science in Wildlife Ecology and Management from University of Georgia. Her Masters research focused on the importance of downed wood for amphibian, reptile, and shrew communities in southeastern pine communities.

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