2020 Breeding Season (Mostly) Successful for California Red-legged Frogs in Golden Gate

California red-legged frog egg mass production in Golden Gate National Recreation Area from 2001-2020. Note: Surveys began in Redwood Creek and Tennessee Valley in 2002, Mori Point in 2004, Rodeo Valley in 2005, and at Rancho Corral de Tierra in 2012. PROVISIONAL DATA SUBJECT TO CHANGE. NPS / GGNRA

March 2020 - Golden Gate National Recreation Area biologists have been monitoring federally threatened California red-legged frogs in the park for 20 years. Specifically, they count egg masses each winter as a proxy for how well the frogs are doing overall. Last year, they missed out on some peak season counts during the government shutdown. But this year, biologists were able to complete their surveys prior to local shelter-in-place orders to slow the spread of COVID-19. Their findings were heartening! They counted a new record of over 600 egg masses in the park. Furthermore, these egg masses were distributed among a dozen different sites within seven different regions of the park. Taken together, the robust numbers of egg masses and breeding sites point to an increasingly resilient California red-legged frog population in Golden Gate.

This year, biologists found two adult California red-legged frogs carcasses that had been partially eaten in the middle of egg laying. They found several others that had been hit by cars trying to reach their breeding sites. It's tough being a frog! NPS / Gabi Dunn

The rising numbers of egg masses in the park are being driven by increases in recent years at locations in Marin County, including Rodeo and Tennessee Valleys in particular. For example, biologists found egg masses in Tennessee Valley for the first time in 2015, and have since recorded exponential increases. This year, they counted a new record total of 158 egg masses! Frogs in Lower Redwood Creek, where egg masses were newly translocated in 2010-2011, also continue to reproduce successfully. Biologists counted 118 egg masses there this winter. Interestingly, biologists have also observed a couple of adult frogs partially eaten in the middle of egg laying, and others hit by cars trying to get to their breeding sites this year in Marin. It sure is tough to be a frog!

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