Effect of nest temperature on egg-brooding dynamics in Children's pythons.

Parental care meets several critical needs of developing offspring. In particular, egg brooding in pythons is an exceptional model for examining environmental influences on specific parental behaviors because brooding behaviors are dynamic yet simple and modulate embryonic temperature, respiration, and water balance. We used captive Children's pythons (Antaresia childreni) to assess their facultative endothermic capability, the influence on egg-brooding behaviors of the gradient between the nest temperature (T(nest)) and clutch temperature (T(clutch)), and the effect of these behaviors on the developmental micro-environment. We monitored maternal egg-brooding behavior, rates of brooding unit (i.e., female and associated clutch) respiratory gas exchange, T(nest), T(clutch), and intra-clutch oxygen tension (PO(2)clutch) during acute changes among four incubation temperature conditions: constant preferred temperature (31.5 degrees C); 'cooling' (T(nest)<T(clutch)); constant cool temperature (25.6 degrees C); and 'warming' (T(nest)>T(clutch)). We demonstrated that A. childreni are not facultatively endothermic because brooding unit temperature coefficient (Q(10)) for V(O2) and V(CO2) was similar to other ectothermic boid snakes (1.9-5.7) and T(clutch) conformed to T(nest) at the constant, cool temperature treatment. Females coiled tightly around eggs more often during cooling than during warming. Further, the amount of time that females spent tightly coiled during warming significantly affected the T(nest)-T(clutch) gradient. Together these results indicate that, although female A. childreni are not facultatively endothermic, they are capable of assessing the T(nest)-T(clutch) gradient and making behavioral adjustments to enhance the thermal micro-environment of their developing offspring.