Recovery plan for Rana draytonii in northwestern Baja California
Rana draytonii, also known as the red-legged frog, is a species endemic to the Mediterranean region of California and northwestern Baja California. It is the largest frog native to western North America.
Main characteristics
Adult females are significantly larger than males, with an average snout-tail size of 13 cm versus 11.5 cm for adult males.
The ventral part of the hind legs of adult frogs is characterized by a reddish or salmon pink color, and the dorsum is brown, gray, olive or reddish brown, marked with small black spots and larger, irregular dark spots. In Baja California this species has reddish coloration only on the hind legs and not as marked as the frogs of northern California.
The red-legged frog is highly aquatic and is usually found in pools or ponds near streams.
The song of the male red-legged frog is a soft, low volume sound compared to other frogs in the region. It consists of 5 to 7 notes that last approximately 3 seconds and are similar to a moan or grunt. The songs are heard mainly during the breeding season which is between January and March in Baja California.
Location
Historically, this species inhabited continuously from northern California to northwestern Baja California. Red-legged frogs were abundant throughout much of California, however, the species is now nearly extinct both in the Sierra Nevada and south of its range in California, U.S.A. Currently, something similar has occurred in Baja California and it is only present south of its range.
The red-legged frog is listed by the International Union for Conservation of Nature (IUCN) as Vulnerable, and in Mexico it is classified as Endangered on SEMARNAT's NOM-059 list of protected species.
Factors that have contributed to the population decline of this species include habitat destruction and degradation, urbanization, overgrazing by unmanaged livestock, overexploitation of water, and the introduction of exotic species.
What are we doing?
1
Pond creation and maintenance
2
Population monitoring
3
Reintroduction at historic sites
Pond creation and maintenance
One of the problems faced by the red-legged frog is the lack of mating sites, so in 2018 we began the construction and restoration of pools that would allow the species to increase the number of its populations. To date, five pools have been built and one more has been restored. These pools have been constructed at three of the ten sites where red-legged frogs still persist in Baja California. Additional ponds have also been constructed at historic locations where frogs have been extirpated and which will serve as future habitat for introductions at these sites.
The ponds are constructed near the stream where the frogs naturally inhabit, and in 2020 the ponds were used for the first time, recording a total of 14 egg masses between the constructed and restored ponds, demonstrating the importance and success of the project.
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An important factor has been the maintenance of the pools, which is done through the removal of overgrown aquatic vegetation such as tule, which although important as a place of refuge and egg laying, in excess can cause the total loss of the pool, which is why every year in autumn a manual removal of 70-80% is done to ensure that the pool remains functional. This has been accomplished with the help of multiple volunteers, who happily help care for the frogs' habitat to ensure that they have a safe and available place to lay their eggs in the next breeding season.
You can learn more about the habitat creation actions in a short documentary made in 2018, you can watch it here.
Population monitoring
Beginning in 2019 we conduct annual adult sampling at two sites as part of understanding the status of populations and the impact of conservation efforts. The data estimate few adult frogs for each of the sites (<50), but we expect these numbers to increase soon.
In 2020 we initiated egg mass monitoring at three locations to better understand reproductive success and the importance of conservation efforts. Data collected from 2020 showed that heavy rains often cause a significant loss of egg masses, highlighting the importance of frogs having secure pools that allow their eggs to survive, even in the face of heavy rains.
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In 2021 we built a pool in the San Rafael stream, increasing the number of recovery actions to three sites. We also visited the Crane in the Sierra San Pedro Mártir to evaluate the habitat and present threats, which will allow us to initiate actions that will prevent the extinction of this unique population of the red-legged frog.
We are currently monitoring the populations of Rana draytonii in the constructed ponds, and maintaining the ponds to ensure that they can continue to be used for the breeding season. We share with you that in a population located in Rancho Meling we have just counted 150 egg masses, where 3 years ago there were only 14. This shows us the importance and success of the project.
Reintroduction at historic sites
One of the objectives to achieve the recovery of the species throughout its distribution is its reintroduction in historical sites, this is only possible once the threat that led to the extirpation of the populations has been eliminated and the habitat restored. In Baja California this is still a long way off, however southern California was already ready to see red-legged frogs back in their home.
In 2019 we began collaborating with multiple institutions in California and given the excellent work of each of them, in March 2020 the first reintroduction of the red-legged frog to southern California from Baja California took place, making it possible to observe again a species that had been extirpated for more than 20 years. In 2021, 2022 and 2023 more reintroductions were carried out, we hope that these are the first of many sites where the frog can return and we can once again enjoy its song.
You can read about the 2020 reintroduction in a story published in the Los Angeles Times, and about the 2021 activities in The Press Enterprise.
A sculpture in their honor
If you are a resident of Ensenada, we invite you to visit the Riviera Civic and Cultural Center, where you can see a sculpture of the amazing red-legged frog, a wonderful work of art made out of tires by artist Jorge Soto, located in the pavilion on the Coastal Boulevard in front of the Riviera.
The purpose of this frog is to let people know which are the local species that need our care and protection, as well as to raise awareness about how we can take care of the world we live in.
We invite you to read more in the article published by El Vigía.
What's the next step?
We still have a long way to go, but we continue to walk step by step. To date (2024) we have built 10 ponds and carried out more than 8 translocations to the United States. Our goals include increasing the genetic diversity of populations in more locations here in Northwest Mexico, expanding their habitat and thus repopulating where they were once extirpated.
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our efforts in the region.
