Sexual division of nestling parental care in the Pale-breasted Thrush (Turdus leucomelas)

Abstract

Studies of parental care in tropical birds are still relatively scarce in comparison with northern temperate species, especially regarding to the division of parental tasks, leading to a biased and incomplete knowledge of avian reproductive strategies. Herein, we studied the sexual division of parental care in a sexually monomorphic Neotropical passerine, the Pale-breasted Thrush (Turdus leucomelas). We recorded food provisioning and food quantity rates (e.g. feeding trips/h and food items/h, respectively), nest sanitation rate (e.g. events of faecal sacs removal/h), and the time devoted to nest attendance and brooding behaviours by each parent. Throughout the 2015–2017 breeding seasons, we video-recorded 153.5 h of parental care in 33 nesting attempts by 26 breeding pairs in a suburban area of south-eastern Brazil. We found that males had higher food provisioning rates and delivered more food items to larger broods, while female did not respond to brood size. As expected, brood age positively affected food provisioning and food quantity rates of both sexes. Faecal sacs were removed predominantly by ingestion throughout the nesting stage, and males had higher nest sanitation rates. Nest attendance reached 34 ± 27% of the time and decreased with nestling age following a decrease in brooding behaviour, a female-only task, while males stayed in the nest for only 4 ± 4% of observation time. Although most of the parental activities are performed by both sexes, males and females differed in which tasks they invested the most, with brood size and brood age being important modulating factors.