Washington State Conservation Translocation Strategy for the Northern Leopard Frog (Lithobates pipiens)Phase 1: Background, strategy, and implementation of reintroduction to the Columbia National Wildlife Refuge 2012-2024

This document has been developed to summarize the conservation translocation activities for northern leopard frogs (Lithobates pipiens) in Washington. Conservation translocation, or simply “translocation” refers to the deliberate movement of organisms from one site for release in another (IUCN 2013, Linhoff and others 2021). It is the umbrella term used for activities that include reintroduction, reinforcement, and introduction. This document covers Phase 1 during the years 2012-2024. It includes 1) Information on the preparation work that was done before implementation, 2) Information on the reintroduction to the Columbia National Wildlife Refuge, 3) protocols to support the translocation work, 3) goals and success indicators, 4) major difficulties faced, 5) major lessons learned, and 6) recommendations for near future actions related to this project.

This document provides information on current knowledge and research, expert opinion, and highlights limitations and challenges. These details inform the strategy and influence the initial methodologies selected and success indicators. We recognize that amphibian reintroductions are challenging, require substantial planning and financial resources are labor-intensive, require long-term commitment, and have variable results. Amphibian and reptile translocation evaluated from 1991-2006 were only successful about 41% of the time (Germano and Bishop 2009). That was, however, twice the rate reported in an earlier review in 1991 suggesting that our knowledge is improving. The number of amphibian translocations has been increasing in recent decades. Consequently, there are more resources available to help guide these activities (Linhoff and others 2021).

Amphibian reintroductions are not particularly well understood, should be considered experimental, and adaptive management is critical for success (Linhoff and others 2021). We started the pre-translocation planning and risk assessment work in about 2012. We laid out our initial plan for this translocation project in our proposal for the 2018 Competitive State Wildlife Action Grant (C-SWG). We have altered some aspects to improve our methods and techniques. We have also greatly increased the resources dedicated to this effort in terms of funding, staff, and dedicated time. This translocation strategy will be updated and revised as projects move forward and new information becomes available. Washington Department of Fish and Wildlife (WDFW) implementation of this strategy is subject to priorities and budgetary constraints of WDFW and partners.

WDFW is the lead management authority for the northern leopard frog. WDFW will lead this work in consultation with members of Washington’s Northern Leopard Frog Translocation Team, an interdisciplinary group assembled by WDFW specifically for the translocation and recovery efforts. WDFW values this expertise and collaboration. Entities involved in Phase 1 include WDFW, US Fish and Wildlife Service (USFWS), Oregon Zoo, Northwest Trek Wildlife Park (NW Trek), and Washington State University (WSU). Members have expertise in herpetology, wildlife biology, ecological developmental biology, spatial ecology and conservation genetics, veterinary medicine, amphibian pathology, animal husbandry and care, habitat management, data collection and management, population modeling, and project and grant management.

The northern leopard frog was listed in Washington as endangered in 1999 when only two populations could be found (McAllister and others 1999). Only one population remains, and the area occupied by this population has declined since listing. This last population occurs in the Potholes Reservoir area on the Columbia Basin Wildlife Area in Grant County. In the 1980s, leopard frogs occupied seven management units. Systematic surveys conducted in 2003-2004 and 2014 revealed a reduction to four, and then three occupied management units respectively (Germaine and Hays 2007, 2009, Duvuvuei and others 2015). There has been a rebound in recent years, and northern leopard frogs are present in six of the seven management units (WDFW unpubl. data). This population is faced with a long list of threats, including many that cannot be ameliorated. Consequently, the risk of extirpation of northern leopard frogs from the state is high unless management actions can reverse this trend. Translocation interventions are necessary to disperse the species to more places within the historical range. At this point, it is not possible to find ideal translocation sites because of the wide-spread nature of some of the most severe threats. Consequently, part of the site selection criteria is determining if ameliorating threats is possible, what those management actions would be, cost of those actions, and if those needs would be short-term or long-term.

One of the major challenges for northern leopard frog recovery work in Washington has been obtaining sufficient funding because the overall security of the species limits sources of funding. The northern leopard frog is one of the most widely distributed amphibians in North America and is common in many areas. It is ranked as “Globally Secure” (G5) by NatureServe and “Least Concern” by the IUCN Red List. A petition to list the northern leopard frog in the Western United States as Threatened under the Endangered Species Act was found not warranted on October 5, 2011, by the U.S. Fish and Wildlife Service (76 FR 61896). This petition included 21 states. Never-the-less, the conservation concern is dire for the western-most states and provinces (NatureServe 2022). Northern leopard frogs are critically imperiled (S1) in Washington and British Columbia with only a single remaining population each. In Oregon, the species is critically imperiled (S1S2) and there is uncertainty about their status as indicated by their designation as a “Data Gap Species” in the Oregon Conservation Strategy (2016). There are no iNaturalist observations of wild leopard frogs for Oregon (accessed April 28, 2022). The most recent record in the Oregon Department of Fish and Wildlife non-game database is 2003 and 1976 for VertNet (Kalysta Adkins, pers. comm. May 3, 2022). In the adjacent states and provinces of Alberta, Idaho, California, and Nevada, the northern leopard frogs are imperiled (S2).

In 2018, Washington, Idaho, and British Columbia collaborated and were successful in getting a C-SWG. In 2020 and 2023, Washington was again successful in getting C-SWG funding to continue the northern leopard frog recovery efforts. In 2022-24, funding from Supplemental Feed Route mitigation funds and Odessa mitigation funds were used to hire technicians to contribute to this work. In 2024, WDFW dedicated significant funds toward bullfrog suppression at the reintroduction site. Similar funding levels will be needed to continue the work going forward.

The structure of this document follows that of the WDFW state status reports and recovery plans. The first part provides a species profile and background information. This is intended to familiarize the reader with the species and provide information that is relevant to the translocation work. It is not intended to be comprehensive. The second part addresses the translocation strategy and implementation. WDFW has not developed a structure for reintroduction plans. Consequently, the standardized format used in the IUCN Global Reintroduction Perspectives series (Soorae 2018) was used and modified for our needs.

The literature on northern leopard frogs is voluminous due to their widespread distribution and use as research animals. Much published information on “Rana pipiens” pertains to other species described or recognized since the early 1970s, and to populations in the eastern United States where the leopard frogs occupy climates and habitats notably different than in Washington (NatureServe 2018) although the life history information is similar. We depend heavily on unpublished WDFW reports and personal communications with biologists that have worked with the leopard frogs at Potholes Wildlife Area and in western Canada. We have also gleaned information from unpublished reports of other entities doing similar translocation work with northern leopard frogs in the western United States.