Growth, survivorship and longevity of painted turtles, Chrysemys picta, in a southwestern Michigan marsh
American Midland Naturalist
This paper reports results of a mark-recapture study of painted turtles inhabiting a marsh in Kalamazoo County, Michigan, first begun in 1964-1966 and continued intermittently from 1980-1989. The relationship between plastron length (PL) and age (t) was described by von Bertalanffy growth equations for males PL = 111.8(1 - 0.792e-0.184t) and females PL = 152.2(1 - 0.852e-0.128t). Annual survivorship of males and females (≥6 yr old) was estimated as 0.64-0.83 and 0.29-0.50, respectively. Annual survivorship of juveniles (<6 yr old) was 0.21-0.51. Based on estimated minimum ages of individuals first captured as adults in the 1960s and recaptured in the 1980s, the four oldest males were 31 and the oldest female was 34 yr old. The oldest known-age male and female were 21 yr and 15 yr old, respectively. A comparison of data from the 1960s with that gathered in the 1980s revealed that the growth rates of juveniles and the density of turtles in the marsh have increased, while survival rates have apparently decreased. We speculate that the enhanced growth rates and population density are the result of warmer and drier weather during the 1980s.
Frazer, N. B., J. W. Gibbons and J. L. Greene. 1991. Growth, survivorship and longevity of painted turtles, Chrysemys picta, in a southwestern Michigan marsh. American Midland Naturalist 125:245-258.