Food supplementation increases nestling provisioning and nest attendance in the Pale‐breasted Thrush ( Turdus leucomelas )

The reproductive success of altricial birds strongly depends on parental investment to warm, feed and protect their offspring, tasks usually divided asymmetrically between parents. These costly demands can generate conflict between parents over the allocation of effort between offspring care and self‐maintenance. The aim of this study was to experimentally test how food supplementation affects the sexual division of parental investment during the egg and nestling phases in pairs of Pale‐breasted Thrush Turdus leucomelas . We conducted 1‐h observation sessions under a food supplementation scenario, which consisted of providing a mealworm ( Tenebrio molitor ) portion near the nest, and a control scenario, without added food. We recorded the time invested in incubation or nestling brooding (female‐exclusive tasks), the time spent around the nest by each sex and the frequency of food provisioning to the offspring by each sex. We found that (i) food supplementation did not affect the time invested in incubation or brooding by females; and (ii) males spent more time around the nest than females in both the egg and nestling phases regardless of food supplementation. In the egg phase, parents did not change their behaviour in response to food supplementation, while in the nestling phase, both parents increased the time around the nest and the food provisioning frequency to the offspring when food was added. In addition to demonstrating that the sexes complement each other in biparental care, the results suggest that even ephemeral increases in food availability during the nestling phase alter certain aspects of parental care that may result in greater reproductive success.