Skeletochronological Aging and Age Distribution of a Spotted Frog Population (Rana luteiventris)

Abstract

I produced a methodology capable of aging the species Rana luteiventris by using a process called skeletochronology. My objective was to find out if the age of the individual could be assessed by counting the number of lines of arrested growth (LAG's) from cross-sections of the third digit of the right hind foot. After this process was refined for this particular species, seventy-four individuals were sampled in order to construct a static age distribution of a population of frogs. Samples were collected from May-August 1998 at a small pond in the Lewis and Clark County, Chessman Marshland, 10 km west of Clancy, Montana. Few individuals were found to be five years of age. The majority of the population was dispersed somewhat evenly between metamorphs, 1, 3, and 4-year-old frogs. As expected, no frogs beyond five years of age were observed. There was a notable lack of 2-year-old frogs. However, I was unable to account for the low number of 2-year-old frogs in the population.