The amount and length of parental care varies across species and individuals, and has a strong impact on juvenile survival, a stage that greatly influences population growth. The juvenile stage and the factors that influence it may be particularly important in the tropics, where juvenile recruitment has been shown to be the most sensitive to changes in rainfall, and rainfall regime is predicted to change with climate change. Nevertheless, it is unclear how juvenile recruitment is impacted by rainfall. Parental care in the tropics is extensive, and thus plays a large role in juvenile survival and recruitment. Parental care may be impacted by parental age, breeding time, and food resources, and these factors may be impacted by changing rainfall. We asked the following research question: How do traits of the parents (age, sex), traits of the nest (age of young, time of year), and climate (rainfall, temperature) at three temporal scales affect parental care? We examined parental care in a well-studied tropical bird species, Thamnophilus atrinucha(hereafter antshrike), in Panama during two extreme years (El Niño/La Niña). Nests were videotaped in both incubation and nestling stages to determine nest attentiveness, on-bouts, off-bouts, total food, provisioning rates, and prey load.
Results/Conclusions
Overall, we found that rainfall (daily, monthly, yearly) influenced parental care in the nest period, while adult age only influenced the incubation period and offspring age and temperature only influenced the nestling period. Nest attentiveness, off-bouts, and female prey load were lower in the wet year (La Niña) compared to the dry year (El Niño). During the incubation period, females were more responsive to daily rain and had longer on-bouts with more rain, while during the nestling period, males were more responsive to daily rain and brought more food with more rain. Older young received more care and total food increased with daily temperature. In contrast to temperate birds, we observed that rainfall had a significant impact on parental care across all temporal scales examined and males and females did not vary greatly in their parental care. Climate change in Panama is predicted to cause a drying trend, and previous work showed reduced rainfall reduced juvenile recruitment. Our result of higher parental care during a dry year suggest that reduced recruitment is unlikely caused by a decline in parental care during the nest period, but instead may have to do with what happens after offspring leave the nest.