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Turtle Population Demography: Planning Considerations for Addressing Human
Impacts and Declines in Long-lived Organisms
Long-lived
organisms tend to share a suite of life history characteristics which make them
particularly susceptible to population decline and extinction in a developing
landscape. The suite of life history characteristics includes: highly variable
reproductive success (relative, even successful years aren't that great), low
hatchling/juvenile survivorship, delayed sexual maturity, and high adult
survivorship.
An evaluation of the literature on turtles consistently demonstrates the
necessity of protecting breeding adults to be successful in reversing population
declines. Good buffers can be just as important as wetlands for aquatic and
semi-aquatic turtles. Terrestrial impacts disproportionately affect female
turtles which are exposed more because of nesting forays. The presence of roads
near a wetland is correlated with altered population structure (high male to
female ratios) which is a part of the pattern documented in the extinction of
several turtle populations. Other major problems include collection for the pet
trade, consumption, fishing nets (crab pots for diamondback terrapin)/trawling
(sea turtles), agriculture, and lawn maintenance. Essentially, anything that
removes adults and sub-adults from the population.
Courtesy of
NRCS Technology News, April 2005
(in Adobe PDF).
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