Breeding Dynamics of Gopher Frog Metapopulations Over 10 Years

Abstract

Populations of amphibians that breed in isolated, ephemeral wetlands may be particularly sensitive to breeding and recruitment rates, which can be influenced by dynamic and difficult-to-predict extrinsic factors. The gopher frog Rana capito is a declining species currently proposed for listing under the U.S. Endangered Species Act, as well as one of many pond-breeding amphibians of conservation concern in the southeastern United States. To represent gopher frog breeding dynamics, we applied an occupancy modeling framework that integrated multiple datasets collected across the species’ range to (i) estimate the influence of climate, habitat, and other factors on wetland-specific seasonal breeding probabilities, and (ii) use those estimates to characterize seasonal, annual, and regional breeding patterns over a 10-yr period. Breeding probability at a wetland was positively influenced by seasonal precipitation (Standardized Precipitation Index) and negatively influenced by fish presence. We found some evidence that the amount of suitable habitat surrounding a wetland was positively correlated with breeding probability during drought conditions. The percentage of sampled wetlands (N = 192) predicted to have breeding varied seasonally, annually, and regionally across the study. Within-year temporal patterns of breeding differed across the range: in most locations north of Florida, peaks of breeding occurred in winter and spring months; whereas breeding was more dispersed throughout the year in Florida. Peaks of breeding across the 10-yr period often occurred during or in the season following high rainfall events (e.g., hurricanes). These results have direct applications for site-level management that aims to increase successful breeding opportunities of gopher frogs and other associated pond-breeding amphibians, including monitoring protocol and intensity, removal of fish, and improving terrestrial habitat conditions surrounding wetlands (e.g., via tree/shrub removal and prescribed fire). The results also have implications for better-informed management through the closer alignment of breeding activity monitoring with predicted seasonal peaks. Furthermore, estimates of breeding frequency can be incorporated into population viability analyses to inform forthcoming assessments of extinction risk and designation of the species’ conservation status by the U.S. Fish and Wildlife Service.

Widespread amphibian Perkinsea infections associated with Ranidae hosts, cooler months and Ranavirus co‐infection

“…capito had the highest Pr prevalence and intensity of all species we sampled, and this threatened species is declining throughout most of its range (Crawford et al, 2022;Devitt et al, 2023). Given that Pr mortality events have been documented in R. capito starting in 2005 (Isidoro-Ayza et al, 2017;Landsberg et al, 2013) and R.…”

“…Among the four frog families we sampled, members of Ranidae showed significantly higher Pr infection prevalence and intensity, and Rv trended towards the same pattern, consistent with previous findings for both pathogens (Hoverman et al, 2012; Isidoro‐Ayza et al, 2017; Karwacki et al, 2018). Several species of North American ranid frogs are state and federally protected (Crawford et al, 2022; Harris et al, 2022; Rorabaugh et al, 2020) with at least some declines attributed to Bd, Rv or Pr infections (Atkinson, 2016; Bradley et al, 2002; Hossack et al, 2023; Rorabaugh et al, 2020; Vredenburg et al, 2010). Concerningly, the Florida Gopher frog R. capito had the highest Pr prevalence and intensity of all species we sampled, and this threatened species is declining throughout most of its range (Crawford et al, 2022; Devitt et al, 2023).…”

“…Several species of North American ranid frogs are state and federally protected (Crawford et al, 2022; Harris et al, 2022; Rorabaugh et al, 2020) with at least some declines attributed to Bd, Rv or Pr infections (Atkinson, 2016; Bradley et al, 2002; Hossack et al, 2023; Rorabaugh et al, 2020; Vredenburg et al, 2010). Concerningly, the Florida Gopher frog R. capito had the highest Pr prevalence and intensity of all species we sampled, and this threatened species is declining throughout most of its range (Crawford et al, 2022; Devitt et al, 2023). Given that Pr mortality events have been documented in R. capito starting in 2005 (Isidoro‐Ayza et al, 2017; Landsberg et al, 2013) and R. capito also experiences mortality from Rv (Hoverman et al, 2011), the role of Pr individually and Pr‐Rv co‐infections merits further consideration.…”