Cold Hardiness and Overwintering Strategies of Hatchlings in an Assemblage of Northern Turtles

Abstract

Field and laboratory studies were conducted during 1989—1994 to investigate the overwintering strategies of hatchling turtles representing four families native to western Nebraska. Whereas hatchling snapping turtles (Chelydra serpentina) and spiny soft—shelled turtles (Apalone spinifera) overwinter in aquatic habitats, yellow mud turtles (Kinosternon flavescens) and ornate box turtles (Terrapene ornata) burrow below the natal nest and hibernate in sandy soil. Painted turtles (Chrysemys picta) overwinter within their shallow natal nests, but this species, and T. ornata, tolerate extensive tissue freezing. Overwintering behaviors of these species are consistent with indices of physiological cold hardiness and patterns of geographic distribution. Frost commonly penetrated and persisted below 10 cm, the soil depth at the which hatchling C. picta routinely hibernate. Field and laboratory data suggested that hatchling C. picta survive either by remaining supercooled (unfrozen) or by tolerating tissue freezing, the strategy employed depending on prevailing physiological and microenvironmental conditions. Whereas relatively lower temperatures can be survived in the supercooled state, supercooling capacity may be limited via the inoculation of body fluids by environmental ice. Alternatively, whereas freeze tolerance fortuitously is promoted by ice inoculation, this strategy may be viable only at relatively high subzero temperatures. A cold—hardness strategy based on both survival mechanisms may promote winter survival in hatchling C. picta by conferring protection under dynamic physiological and microenvironmental conditions. Physiological cold hardiness and behavior are integrated determinants of the northern distributions of temperate region turtles.

Lactate accumulation, glycogen depletion, and shell composition of hatchling turtles during simulated aquatic hibernation

“…Turtles lay eggs in shallow nests on land, which hatch in late summer or early fall. Snapping turtle hatchlings emerge immediately after hatching and move to water (Congdon et al, 1987;Costanzo et al, 1995Costanzo et al, , 1999, where they spend their first winter submerged. In contrast, map and painted turtle hatchlings remain in the nest, surviving the freezing temperatures of winter via supercooling or freezetolerance, and emerge from the nest the following spring (map turtles: Costanzo et al, 2001b;Pappas et al, 2000;Baker et al, 2003;painted turtles: Packard, 1997;Weisrock and Janzen 1999).…”

Localization and regulation of a facilitative urea transporter in the kidney of the red-eared slider turtle (Trachemys scripta elegans)

“…When turtles were exposed to a high salinity, plasma osmolality and concentrations of Na + , Cl -and urea increased significantly and urea synthesis also increased (Lee et al, 2006). During hibernation plasma osmolality increased, largely due to the retention of urea, in Chrysemis picta (Costanzo et al, 1995). In hatchling turtles, accumulation of urea might be associated with cold hardiness in the winter (Costanzo et al, 2000).…”

Post-Emergence Movements and Overwintering of Snapping Turtle, <em>Chelydra serpentina</em>, Hatchlings in New York and New Hampshire

“…For the two former species, it is assumed that if the hatchlings leave the nest, they overwinter aquatically, while for the latter species fall emergence coupled with aquatic or terrestrial overwintering has been reported (Draud et al 2004), as well as overwintering in the nest coupled with fall emergence (Baker et al 2006). Other species have been consistently reported to be overwhelmingly fall emergers, including Snapping Turtles (Chelydra serpentina - Obbard and Brooks 1981;Carroll and Ultsch 2007), Spiny Softshell Turtles (Apalone spinifera - Christiansen and Gallaway 1984;Costanzo et al 1995), Musk Turtles (Sternotherus odoratus Cagle 1942;Mitchell 1988), Wood Turtles (Glyptemys insculpta -Harding 1991;Carroll and Ultsch 2007), Spotted Turtles (Clemmys guttata -Ernst 1976;Carroll and Ultsch 2007), and Blanding's Turtles (Emydoidea blandingii -Standing et al 1997-Standing et al , 1999Pappas et al 2000). Hatchlings of most of these species are assumed to overwinter aquatically, even though some may remain on land for extended periods before entering the water; e.g., Wood Turtles (Tuttle and Carroll 2005;Castellano, Behler, and Ultsch, un pub -lished data) and Blanding's Turtles (Standing et al 1997(Standing et al , 1999.…”