Search

Here we report on the demography and reproductive ecology of the Columbia spotted frog (Rana luteiventris Thompson, 1913) breeding in ponds across the Palouse Bioregion of Washington and Idaho. Spotted frogs are unusual, if not unique, among temperate ranids in that males establish the oviposition site before females become active. Females laid at one or two communal sites in shallow water. Our breeding populations were small, never exceeding 50 adults counted, and most displayed male-biased sex ratios. We estimated effective population sizes (Ne) as ranges determined by extremes in male breeding success; these varied between 3.2 and 37.8. Even the latter falls below the minimum required for long-term population viability. Small population size may make spotted frogs vulnerable to genetic problems and environmental insults. Communal oviposition certainly renders a population's reproductive effort vulnerable to variation in hydroperiod, which we observed during the dry spring of 2004. In the absence of information on the degree of "connectedness" among our ponds as subunits of more resilient metapopulations, we suggest that small population size and communal oviposition likely render R. luteiventris vulnerable to anthropogenic disturbance. Furthermore, the status of R. luteiventris on the Palouse may be less secure than assumed currently. [ABSTRACT FROM AUTHOR]