Increased prevalence of mature females bearing pigmented oocytes from populations of Minnesota Rana pipiens.

Mature female leopard frogs, Rana pipiens, collected from several sites in Minnesota from 1967 through 1977, were examined for the presence of pigmented oocytes. An increase in the percent of mature females with pigmented oocytes was observed in the frogs captured in 1977 compared to those captured earlier. Coincident with the increase in prevalence of females with pigmented oocytes, there was a decline in abundance of the frogs.