Annual Frequency of Clutches of Pseudemys Texana and Trachemys Scripta at the Headwaters of the San Marcos River in Texas (Report‪)‬

A measure of fecundity is essential to understanding life-history patterns and for developing life tables. However, fecundity often is underestimated because of an absence of data regarding seasonal variation in number and frequency of nesting events. Turtles are excellent examples of long-lived species with a variety of reproductive patterns, and these patterns might differ for a species based on geography (Iverson, 2001). Few studies have adequately addressed the issue of multiple laying bouts in a given season. Habitat configuration and availability of searching time are primary factors limiting such studies. For example, some turtles nest along sandy embankments that may be widely separated in the system, some nest near water, and some nest more distantly. Rivers, streams, lakes, and ponds all offer unique challenges for monitoring nesting frequency. For example, investigators must be on-site consistently during daily nesting times for the entire nesting season (potentially months), and the habitat at the site must facilitate observation. Consequently, most assumptions about annual frequency of clutches have been derived from dissections (e.g., Sexton, 1959; Thornhill, 1982; Jackson, 1988; Iverson, 2001; Tucker, 2001). Direct evidence for multiple annual laying was lacking for many years but was confirmed by Snow (1980), Tinkle et al. (1981), Balcombe and Licht (1987), and Schwarzkopf and Brooks (1986) for Chrysemys picta. Gibbons (1982) and Gibbons et al. (1982) confirmed that some Trachemys scripta produced two clutches per year. Jackson and Walker (1997) confirmed that a local population of Pseudemys concinna suwanniensis nested over a 4-month period and noted that an individual might produce up to five clutches. Iverson (2001) estimated, based on follicle-size groupings and corpora lutea, that P. concinna from Arkansas probably had two or three clutches a year. Herein, I report on frequency of clutches of P. texana and T. scripta that inhabit a spring system associated with a golf course.