The role of temperature and humidity in python nest site selection

Parental care is a convergent trait shown by a broad range of taxa. Often, successful parents must balance multiple developmental variables (e.g. embryonic water balance and thermoregulation). Pythons have recently emerged as valuable parental care models because females show simple egg-brooding behaviours that significantly influence variables of widespread importance (i.e. embryonic predation, hydration, temperature and respiration). Nest site selection is an important parental behaviour that has been shown to enhance several developmental variables in numerous taxa. In pythons, where brooding can substantially mitigate environmental conditions to enhance the developmental environment, it is unclear to what extent females utilize environmental cues in selecting their nest site. Thus, we determined whether nest humidity and temperature influence python nest site selection because these variables influence python egg-brooding behaviour and are strongly associated with offspring fitness. We created a radial maze with three nest site options: OTH: optimal temperature (31.5 °C) and humidity (23 g/m3 H2O), as determined by previous studies; OT: optimal temperature, suboptimal humidity (13 g/m3 H2O); OH: suboptimal temperature (25 °C) and optimal humidity. We monitored the locations of female Children’s pythons, Antaresia childreni, during gravidity, at oviposition and when nonreproductive. Females significantly preferred OTH over OT and OH during both reproductive stages; yet, female choice was not significantly different from random when females were nonreproductive. These results, when considered with previous results, demonstrate that female pythons sense environmental temperature and humidity and use this information at multiple time points (i.e. during gravidity, at oviposition and during egg brooding) to enhance the developmental environment of their offspring.