Drought disrupts year-round breeding readiness in a tropical songbird

Avian Conservation and Ecology

article

Jordan Boersma¹  Erik D. Enbody³  Jordan Karubian³  Heather E. Watts¹  Hubert Schwabl¹ 

[1] School of Biological Sciences, Washington State University;Cornell Lab of Ornithology;Department of Ecology and Evolutionary Biology, Tulane University;Department of Biomolecular Engineering, University of California;Center for Reproductive Biology, Washington State University

关键词: androgens;    brood patch;    cloacal protuberance;    condition;    El Niño;    molt;    phenology;    photoperiod;    testosterone;   

DOI  :  10.5751/ACE-2343-170244

学科分类：口腔科学

来源: Resilience Alliance Publications

【 摘 要 】

Climate change is expected to increase the prevalence and severity of extreme weather events like drought. For many opportunistically breeding tropical bird species, precipitation serves as a primary cue for onset of breeding, and sustained drought can have major impacts on reproductive fitness. The physiological effects of drought are poorly understood, but understanding physiological responses can help resolve the mechanisms underlying effects of drought on population demography. We used physiological data collected on a year-round breeding New Guinea endemic passerine, the White-shouldered Fairywren (Malurus alboscapulatus), during years with persistent rainfall and during the 2015–2016 El Niño drought event to assess patterns of breeding readiness, body condition, and molt. Many males lost their cloacal protuberances, a sperm storage organ they typically maintain year-round, during the drought period. Body molt, which also occurs year-round in this species, was higher in males during the drought period. Using a sliding-window statistical model approach, we identified a critical precipitation window of 0–40 days prior to capture for cloacal protuberance volume and a window of 8–53 days for molt, with lower precipitation associated with smaller cloacal protuberances and greater molt. Plasma androgens were predictive of variation in male cloacal protuberance volume and molt, thus potentially mediating transitions between life-history stages in response to environmental conditions. Female molt, androgens, and male mass varied with photoperiod, with longer but decreasing day lengths characteristic of the austral summer associated with increasing molt and decreasing androgens. Collectively, our results indicate the potential for photoperiod to cue some life-history stages, whereas reduced rainfall impacts male but apparently not female reproductive physiology and readiness to breed. Improving our understanding of environmental regulation of life-history transitions in tropical taxa is essential for identifying which taxa are most at risk under a changing climate.

【 授权许可】

CC BY