Carl H. Ernst
Evelyn M. Ernst
Julia L. Riley
Jeffrey E. Lovich
2014
<p>Hatchling emergence patterns were studied in a community of six species of freshwater turtles in Lancaster County, Pennsylvania, U.S.A. including: <em>Chelydra serpentina, Chrysemys picta, Clemmys guttata, Glyptemys insculpta, G. muhlenbergii</em>, and <em>Sternotherus odoratus</em>. Data were collected every year from 1965 to 1985 on estimated date of emergence, carapace length, April – May precipitation, August – September precipitation, annual precipitation, and low temperature and occurrence of precipitation during the 24-hrs prior to the time of each hatchling detection (n = 806). <em>Chelydra serpentina, Ch. picta</em>, and <em>Cl. guttata</em> hatchlings have a facultative delayed emergence strategy. The other species (<em>G. insculpta, G. muhlenbergii</em>, and <em>S. odoratus</em>) appear to be obligate early emergers, with the exception of one hatchling <em>G. muhlenbergii</em> that delayed emergence. Early emergence occurred in some species every year except 1973, the year following intense flooding and nest destruction associated with a major hurricane. However, the majority of hatchlings delayed emergence until the year following oviposition. Mean estimated calendar day of emergence varied annually in <em>C. serpentina</em> and <em>Ch. picta</em>. The same variable also varied among species for comparisons of both early and delayed emergence. <em>Chelydra serpentina</em> hatchlings emerged earlier than all other species whether they used an early or delayed strategy. Carapace length of <em>Ch. picta</em> hatchlings varied significantly among years and <em>C. serpentina</em> hatchlings that delayed emergence were significantly larger in carapace length than those that emerged early. Seasonal and previous 24-hr precipitation had varying effects on the number of emerging hatchlings, but August – September precipitation in one year had a strong correlation with the number of hatchlings that delayed emergence until the following spring. The number of hatchlings detected peaked at a previous 24-hour air temperature of about 12°C for both early and late emergence. Small species like <em>G. muhlenbergii</em> and <em>S. odoratus</em> may emerge early to limit potential hatchling competition in diverse communities of freshwater turtles with primarily delayed emergence.</p>
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The Herpetologists' League, Inc.
A 21-year study of seasonal and interspecific variation of hatchling emergence in a nearctic freshwater turtle community: to overwinter or not to overwinter?
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