Amphibians whose life history follows a complex life cycle often occupy different habitats during their ontogeny. Anuran life stages usually include an aquatic larval stage followed by a terrestrial adult form; marked by a dramatic transition between those stages through the process of metamorphosis. Selective pressures and survival success vary within and among habitats, but theory assumes that size at metamorphosis for individuals confers higher fitness with an increased chance for surviving to reproductive age. Selective pressures may include weather, annual precipitation, competition, predation, and parasites. Here, we present estimates for recruitment and survival in a population of California red-legged frogs (Rana draytonii) over a 4-year period, informed by a program of marking recently transitioned frogs (metamorphs, froglets) with subdural passive integrative transponders. Marked frogs were recaptured periodically through sexual maturity on the Mitsui Ranch Preserve between 2019 and 2022. Recruitment varied between years, with numbers falling to zero in extreme drought, but long-lived terrestrial adults facilitated a prompt recovery.

Jeff Wilcox is the Managing Ecologist for the Mitsui Ranch Preserve on Sonoma Mountain, near Petaluma California. Jeff has managed working landscapes for 27 years, using native amphibians as indicators of rangeland health while cattle to restoring rangeland function and ecosystem services, using cattle grazing as the primary restoration tool.