Wetland Restoration In Baja California (Mexico) To Save California Red-Legged Frogs

Baja California Red-Legged Frog Wetland Restoration Project

Report from Tom Biebighauser, who has built and restored over 2,000 wetlands throughout North America. Tom will be on site full-time directing the construction of the wetlands. He will provide training to biological personnel and heavy equipment operators in the use of techniques he has developed over the past 43-years for restoring wetlands to provide habitat for the California Red-Legged Frog and other rare species in arid regions. Tom has designed and built over 50 wetlands in California to provide breeding habitat for the California Red-Legged Frogs.

We need your help financing the restoration of wetlands that can save the California red-legged frog (Rana draytonii) in Mexico and the United States. SAVE THE FROGS! and The San Diego Natural History Museum helped finance the design of nine-wetlands in Baja California, Mexico, to provide habitat for the California red-legged frog and the Southwestern Pond Turtle (Actinemys pallida). The wetland projects were designed in December 2021 by Dra. Anny Peralta (Fauna del Noroeste A.C.), Thomas R. Biebighauser (Sheltowee Environmental Education Coalition), Dan Taylor (Bat Conservation International), and Jorge Valdez (Fauna del Noroeste A.C.).

The California red-legged frog is the largest native frog in western North America and has lost over 70-percent of its range in California. In Baja California, they are confined to 10 sites with less than 50 individuals at each location, except for one site where conservation actions had been undertaken since 2018. With increasing threats to their survival, including habitat disturbance by livestock, exotic species, and chytridiomycosis, these populations might not hold on for much longer. Genetic analyses of these small populations also indicated lower genetic diversity values compared to similar California populations. The extreme isolation of remnant Baja California populations of Rana draytonii, along with the ongoing threats listed above, highlights the need for fast conservation actions. Based on the background information described above, and with the strong commitment of collaborators and supporters, we have developed a recovery plan that will stabilize existing population numbers and long-term recovery plans to reconnect their historical range. As a first step, we plan to stabilize populations by increasing the number of wetlands around existing populations and increasing connectivity to encourage genetic movement and population growth.

Building these wetlands will help the California red-legged frog survive climate change. There’s a real danger of losing the Mexican populations because there are only a few small wetlands present where the species is breeding, and these wetlands are going dry.

Six of the nine wetlands were designed at El Molino and El Potrero where there are current populations of the California red-legged frog. Two wetlands were designed at the last known site of the species in Baja California, and one site within the historical range, make it them ideal for reintroduction actions. The ranch owners have a sincere interest in helping the California red-legged frog. Dra. Peralta and Jorge Valdez have developed an excellent relationship with these landowners.

Eight of the nine wetlands would be built on large and level areas of ground where the flow from springs keeps the ground saturated year around. These wetlands would be restored in drainages where there is an abundance of healthy riparian habitat. These ranches are grazed by low numbers of cattle and there would be no conflict with California red-legged frog management as the ranches are not open to the public and are accessed by infrequently traveled dirt roads.

The wetlands would be built where the nonnative American bullfrog and large nonnative fish are not present. This is important because the American bullfrog and nonnative fish can limit populations of the California red-legged frog.

In 2018 and 2019 Dra. Peralta and Jorge Valdez built 3 medium size (~300 m2) wetlands for the California red-legged frog on the Rancho Meling and, two small ponds (~50 m2) at El Potrero Ranch. The California red-legged frog is successfully breeding at Rancho Meling constructed wetlands. The El Potrero ponds should be made larger. The wetlands designed for this project would be built much larger and deeper, and would contain features such as shallow water bays, woody debris, loafing logs, pits, and mounds for improved habitat.

The California red-legged frog is in danger of extinction in Mexico and the United States. Building these wetlands will help recover populations of the California red-legged frog across Southern California and in Mexico. This is because there are two genotypes of the California red-legged frog in California, the Northern and the Southern. The Southern genotype has been extirpated from California. Fortunately, the Southern genotype is still present in Baja California, Mexico. Building the designed wetlands will increase populations of the Southern genotype in Mexico. Successful conservation actions at Rancho Meling, had led to collaborative efforts to reintroduce the southern genotype to extirpated areas in southern California. This population can also serve as a donor for reintroduction into extirpated areas in Baja California, however, other genetics populations as the one from El Potrero, need to be restored, to increase genetic diversity in reintroduced populations, and allow higher survival rates.

Building wetlands at El Potrero, and Agua Caliente ranches would also greatly improve habitat for the southwestern Pond Turtle.  This species has been petitioned to be threatened under the Mexican threatened species list, and is a species of concern in California. The population of this species at El Potrero and Agua Caliente are considered to be low in numbers, probably due to the lack of habitat (large ponds). The restored wetlands would go a long way in increasing the existing low populations of the Southwestern Pond Turtle that are found on these ranches.

Naturally appearing and functioning wetlands that contain water year-round would be built so they do not require maintenance. No dams, berms, dikes, levees, diversions, wells, pumps, or water control structures will be used. The wetlands will be built so they would not be damaged by flooding, livestock, or humans.

The wetlands will be built with the following features to provide habitat for frogs, turtles, waterfowl, and a diversity of wildlife species:

California Red-Legged Frogs

The wetlands will be built in watersheds that have no large fish or the American bullfrog. Shallow water areas will be shaped in full-sunlight for egg hatching and larval development. Large woody debris and branches will be placed in and around the wetlands for hiding cover. Compacted soils will be loosened for burrowing. A diversity of native plants will be seeded and planted. The wetlands will be distant from roads within a large area not open to the public. The area is not being used for recreation by off road vehicles which means there is little risk of amphibians being crushed by motor vehicles.

Southwestern Pond Turtles (Actinemys pallida)

A diversity of wetlands will be built. Ridges of sand will be formed on higher ground in full sunlight to create nesting sites. Large logs will be placed in the wetlands for basking. Large woody debris and branches will be placed in and around the wetlands for hiding cover. Compacted soils will be loosened for burrowing and for egg laying. A diversity of native plants will be seeded and planted. The wetlands will be distant from roads in an area not open to the public. The wetlands will be built in a watershed that has no large fish or American bullfrogs that eat turtle hatchlings and compete with turtles for food.

Waterfowl

The wetlands will be built so they contain a diversity of water depths, slopes, and plant species. This will be done by making dips, pits, mounds, pools, ridges, points, and peninsulas in the wetland basins. Compacted soils will be loosened to facilitate invertebrate and plant colonization. The wetlands will be built in a watershed that has no fish or American bullfrogs that eat ducklings and compete for waterfowl for food. A diversity of flowering plants used by pollinators will be sown on the soils removed from building the wetlands. These areas will provide waterfowl with nesting habitat.

Bats

Up to 12 species of bats will use the new wetlands for drinking and foraging. The center of each wetland will be made deep so that cattails will not cover the surface. The open water areas will be of great importance to bats for drinking. A diversity of flowering plants used by pollinators will be sown on the soils removed from building the wetlands. The moths attracted to these plants at night will provide food for bats.

We greatly appreciate your help funding one or more of these wetlands to be built in Mexico to help save the California Red-Legged Frogs!