Kinosternon Reproductive Cycle 39 



AGE, GROWTH, AND SIZE AT MATURITY 



Females possessing ovarian follicles exceeding 7 mm diameter (or 

 oviducal eggs or corpora lutea) during the months of July through May 

 were considered mature. The three smallest mature females had plastral 

 lengths of 69.4, 70.2 and 72.7. The four largest females judged to be im- 

 mature measured 66.6, 67.9, 74.8, and 79.6 PL. Maturity therefore occurs 

 at sizes between 70 and 75 PL (75 to 80 CL). I believe the 79.6 PL im- 

 mature was reproductively anomalous since nine other females with 

 plastron lengths between 75 and 80 mm were mature. The smallest 

 mature female dissected by Einem (1956) was 81.2 mm CL and the 

 largest immature female was 71.1 mm CL. 



Age at maturity was estimated by counts of clearly visible winter (or 

 primary) abdominal scute annuli as described by Sexton (1959). The 

 oldest immature females bore six clear primary annuli (74.8 and 79.6 

 PL); the youngest mature female had only five (73.1 PL), indicating the 

 usual age at maturity to be five or six years. 



Plastron lengths calculated from the abdominal scute annuli lengths of 

 19 juvenile and young adults in the manner of Ernst et al. (1973) in- 

 dicated turtles in their first winter averaged 17.9 PL (Range = 14.4-20.6, 

 N = 19). Those in their second winter averaged 32.7 PL (25.5-39.0, N = 

 19); in their third winter, 45.7 (34.3-56.8, N = 14); fourth, 57.8 (49.3- 

 64.3, N = 11); fifth, 68.9 (62.8-76.9, N = 9); sixth, 74.3 (69.1-82.0, N = 

 8); and in their seventh, 75.1 (71.1-83.8, N = 7). If turtles are maturing at 

 plastral lengths of 70-75, these data support the contention that maturity 

 occurs during the fifth to sixth years of age. 



Average size of 101 adult females previously examined from throughout 

 Florida (Iverson 1978b) was 86.2 PL (91.6 CL) [52 males averaged 73.1 

 PL, 83.7 CL]. The largest female measured 105.1 PL and 114.7 CL. The 

 PL-body weight (in gm) regression, based on six females (69.1-90.0 mm 

 PL, and 64.5-143.1 gm), is Wt - 3.36 PL - 154.84 (r = 0.92; p<0.01). 

 From this regression the average female (86.2 PL) weighs 135.1 gm. 



FEMALE REPRODUCTIVE CYCLE 



The ovarian cycle is nearly continuous (Table 1), with only a short 

 summer quiescent period (coincident with the summer reduction in ac- 

 tivity). Ovulation occurs from late August or early September to early 

 June. Based on excavated nests and the presence of oviducal eggs, females 

 apparently nest from September through June. Females continue to yolk 

 follicles to replace those ovulated during all but the last of this period. 

 Follicular enlargement is curtailed only from late May through June. 

 During the remainder of the year enlarged follicles (> 7 mm) are 



