Life-history of a population of Cottonmouths in east-central Alabama Scott Boback, Matt Greene, Roger Birkhead, Matt Williams, and Dave Koons How do organisms respond to environmental variation? Comparative life-history can help us understand how organisms respond to variation in the environment. A. p. piscivorus A. p. leucostoma A. p. conanti Methodology Results Four years of sampling every two weeks 391 captures of 198 individuals 49% adults SVL (cm) Number of Snakes Males Females Body Size Body Mass (g) Number of Snakes Males Females Body Size Mean Male SVL (cm) ARNCVA AL AR SC 67.9 Body Size SSD Index Equal ARNCVA ARSCALFL Sexual Size Dimorphism Sex Ratio (F:M) March June 15 June 16 October 1:1 Sex Ratio Sex Ratio Cormack-Jolly-Seber estimator for open populations Survival = probability that a snake alive in week i survived and did not permanently emigrate from study area in week i+1 Recapture = probability that a marked snake alive in week i did not permanently emigrate and was captured in week i+1 Survival Analysis- MARK Recapture Probabilities SVL (cm) Weekly Recapture Probability Annual survival = 0.79 Recapture probability higher in first year Strong effect of transient individuals Litter size = 4.11.5 (N=11) RCM = 26.29.3 (N=7) Frequency of pregnancy from 91% - 15% Reproduction Mean Litter Size TXNCVAFLARSCALFLTXVA 4.1 Litter Size Midpoint SVL (cm) Growth Rate (cm/month) Growth Field Data Males Females Midpoint SVL (cm) Growth Rate (cm/month) Growth Lab Data Males Females Midpoint SVL (cm) Growth Rate (cm/month) Growth Field versus Lab Field Lab J F M A M J J A S O N DA S O N D SVL (cm) J F M A M J J A S O N D Polyphasic Growth Summary High annual survival Likely a long-lived species Frequency of reproduction highly variable Small litter size Slow growth but capable of extremely rapid growth when resources are abundant Acknowledgements