Influence of Hydric Conditions during Incubation and Population on Overland Movement of Neonatal Snapping Turtles

Abstract

The amount of water available during incubation, both from maternally(Finkler, 1997; Finkler and Claussen, 1997) and environmentally-derived sources (Packard et al., 1977; Packard and Packard, 1988; Packard, 1991) has a profound influence on embryonic development. Differences in the amount of water available to the developing embryo likely impact cardiovascular function and the rate of nutrient delivery to the embryo, which in turn influence metabolism, growth, and developmental rate (Packard, 1991). Compared to hatchlings that experience drier conditions during incubation, those from eggs incubated under moist conditions tend to have longer incubation periods, have larger body masses and carapace lengths, have increased water contents, and have less yolk remaining in their yolk sacs at hatching (Packard, 1991). Although the influence of moisture on embryonic development has been examined extensively, data on its importance to the fitness of the resultant hatchlings are lacking (Janzen, 1993). Most studies that have examined long-term effects of incubation moisture on hatchling growth and performance (e.g., Brooks et al., 1991; Miller, 1993) have done so under controlled laboratory conditions (constant temperature, etc.) as opposed to conditions more analogous to those experienced in the field. Thus, there is some question as to whether increased moisture during incubation confers long-term benefits to hatchlings under natural conditions.