Range-wide persistence of the endangered arroyo toad (Anaxyrus californicus) for 20+years following a prolonged drought

Prolonged drought due to climate change has negatively impacted amphibians in southern California, U.S.A. Due to the severity and length of the current drought, agencies and researchers had growing concern for the persistence of the arroyo toad (Anaxyrus californicus), an endangered endemic amphibian in this region. Range-wide surveys for this species had not been conducted for at least 20 years. In 2017-2020, we conducted collaborative surveys for arroyo toads at historical locations. We surveyed 88 of the 115 total sites having historical records and confirmed that the arroyo toad is currently extant in at least 61 of 88 sites and 20 of 25 historically occupied watersheds. We did not detect toads at almost a third of the surveyed sites but did detect toads at 18 of 19 specific sites delineated in the 1999 Recovery Plan to meet one of four downlisting criteria. Arroyo toads are estimated to live 7-8 years, making populations susceptible to prolonged drought. Drought is estimated to increase in frequency and duration with climate change. Mitigation strategies for drought impacts, invasive aquatic species, altered flow regimes, and other anthropogenic effects could be the most beneficial strategies for toad conservation and may also provide simultaneous benefits to several other native species that share the same habitat.

Automated summary

Prolonged drought caused by climate change has had a negative impact on amphibians in southern California. The arroyo toad, an endangered endemic species in the region, has been a concern due to the severity and duration of the current drought. A collaborative survey conducted from 2017 to 2020 confirmed the presence of the arroyo toad in historical locations, indicating their persistence in the face of drought. However, the population's vulnerability to prolonged drought and the predicted increase in drought frequency and duration with climate change highlights the need for mitigation strategies to protect the toads and other native species that share their habitat.