Direct and indirect effects of high temperatures on fledging in a cooperatively breeding bird. (20th July 2021)

• Record Type: Journal Article
• Authors: Bourne, Amanda R; Ridley, Amanda R; Spottiswoode, Claire N; Cunningham, Susan J
• Editors: Candolin, Ulrika
• Is Part Of: Behavioral ecology. Volume 32:Number 6(2021)
• Page Start: 1212
• Page End: 1223
• Publication Date: 2021-07-20
• Subjects: avian reproduction -- climate change -- cooperative breeding -- dryland ecology -- environmental variability -- reproductive success -- survival of young; Animal behavior -- Periodicals; Behavior evolution -- Periodicals; Ecology -- Periodicals; Psychology, Comparative -- Periodicals; 591.5
• DOI: 10.1093/beheco/arab087
• Languages: English
• ISSNs: 1045-2249

Abstract

Abstract: High temperatures and low rainfall consistently constrain reproduction in arid-zone bird species. Understanding the mechanisms underlying this pattern is critical for predicting how climate change will influence population persistence and to inform conservation and management. In this study, we analyzed Southern Pied Babbler Turdoides bicolor nestling survival, daily growth rate and adult investment behavior during the nestling period over three austral summer breeding seasons. High temperatures were associated with lower body mass, shorter tarsi, and reduced daily growth rates of nestlings. Our piecewise structural equation models suggested that direct impacts of temperature had the strongest influence on nestling size and daily growth rates for both 5-day-old and 11-day-old nestlings, followed by temperature-related adjustments to provisioning rates by adults. Rainfall and group size influenced the behavior of provisioning adults but did not influence nestling growth or survival. Adjustments to adult provisioning strategies did not compensate for direct negative effects of high air temperatures on nestling size or daily growth rates. Detailed mechanistic data like these allow us to model the pathways by which high temperature causes nest failure. In turn, this could allow us to design targeted conservation action to effectively mitigate climate effects. Abstract : Hot and dry weather can limit breeding success in arid-zone birds. Southern pied babbler nestlings in the Kalahari grow more slowly during hot and dry weather and are smaller at fledging age. Pied babbler adults adjust their provisioning strategies to young during hot weather, but this does not compensate for the large, direct effect of high temperatures on nestling size and daily growth rates. Increasingly hot conditions due to climate change may therefore threaten this and other arid-zone species.