Data from: Effects of partner workload and increasing environmental temperature on nestling provisioning and body temperature in a declining aerial insectivore

With climate change, birds will face increasing thermoregulatory demands,
which may alter reproductive behaviors such as offspring provisioning.
Experimental studies have shown that the provisioning capacity of female
tree swallows (Tachycineta bicolor) is limited by their risk of
overheating. Given that parental investment strategies may vary between
sexes, the thermal environment may have a different impact on males. We
experimentally trimmed ventral feathers from male tree swallows to create
a “thermal window” through which they could dissipate heat. We remotely
monitored the provisioning rate and core body temperature of males and
their female partners. At high temperatures, all males decreased their
nestling provisioning rates irrespective of trimming treatment. In
addition, trimmed males maintained core body temperatures similar to those
of controls. This suggests that, in contrast to previous work with
females, males limit provisioning rates to levels below the threshold at
which they would overheat. Females paired with trimmed males adjusted
their own activity to match that of their male partners; whether there are
costs to females is unknown. Combined, these studies highlight that
sex-specific differences in thermal physiology and behavior must be
considered when predicting responses to climatic warming.