Acute elevation of the heat load of mother rats curtails maternal nest bouts.

Elevation of the rate of rise of ventral, core, or preoptic area temperature in mother rats while they were nesting with their offspring curtailed nest-bout durating. In addition, the naturally occurring curtailment of nest bouts that occurs in mothers caring for large pups was found to be accompanied by an elevated rate at which maternal temperature rose over the course of a nest bout. These data are consistent with the suggestion that nest-bout duration is thermally limited.