Gc. Packard et al., THERMAL ENVIRONMENT FOR OVERWINTERING HATCHLINGS OF THE PAINTED TURTLE (CHRYSEMYS-PICTA), Canadian journal of zoology, 75(3), 1997, pp. 401-406
We monitored temperatures during the winter of 1995-1996 inside 18 nes
ts containing hatchling painted turtles (Chrysemys picta). The study w
as performed at the Valentine National Wildlife Refuge in north-centra
l Nebraska to assess survival of neonatal turtles in relation to the t
hermal environment inside their hibernacula. Minimum temperatures in t
he nests varied from -3 to -21 degrees C, and were better predictors o
f survival of hatchlings than other measures of the thermal environmen
t. All hatchlings survived in nests where the temperature never went b
elow -7 degrees C, some animals survived in nests where the minimum wa
s between -7 and -13 degrees C, but no turtle survived in a nest where
the minimum was below -14 degrees C. Hatchlings probably survived the
cold by sustaining a state of supercooling, because the duration of e
xposure to low temperatures was far too long for animals in most nests
to have survived in a frozen state.