Life Tables of a Slider Turtle Population

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Contribution to Book

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Life History and Ecology of the Slider Turtle. J. Whitfield Gibbons


Smithsonian Institution Press

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A complete life table is constructed for the slider turtle, Trachemys scripta, based on the population at Ellenton Bay, South Carolina. Survival from the time eggs are laid until hatchlings enter the water the following spring averages 10.5%. Annual survivorship of 1-, 2-, and 3-year-olds ranges from 53.9% to 82.9%. Annual survivorship of turtles more than 4 years old averages 84.4% for males and 81.4% for females. Annual per capita fecundity of females is estimated as 1.28 female eggs, taking into account a 1:1 sex ratio of eggs and the mean proportion of adult females that are reproductively active in any given year (37%). Various assumptions that must be taken into account are discussed. The population is declining at a rate of 15% per year if both death and emigration are combined to calculate lx. The net reproductive rate (R0) is 0.137, with a realized intrinsic rate of increase (r) of -0.1675. Also presented are alternative life tables representing best- and worst-case scenarios that depict highs and lows of annual variation in survivorship and fecundity estimates.

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