4.5 Article

Too hot to handle? Behavioural plasticity during incubation in a small, Australian passerine

期刊

JOURNAL OF THERMAL BIOLOGY
卷 98, 期 -, 页码 -

出版社

PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jtherbio.2021.102921

关键词

Behavioural plasticity; Climate change; Extreme heat events; Heat dissipation; Incubation; Thermoregulation

资金

  1. South Australian Department of Environment and Water [E267551]
  2. Australian National University Animal Experimentation Ethics Committee [A2018/29]
  3. Australian Bird and Bat Banding Scheme [1535]

向作者/读者索取更多资源

Global warming and intensifying extreme heat events may negatively impact avian reproductive success and costs, particularly in hot, arid environments. This study examines the behavioral plasticity of a small passerine in semi-arid Australia under high temperatures, finding that despite efforts such as shading eggs and positioning nests for shade, extreme temperatures still pose a threat to reproductive success. Increasing frequency and intensity of extreme heat events are likely to further threaten bird populations in these environments.
Global warming and intensifying extreme heat events may affect avian reproductive success and costs, particularly in hot, arid environments. It is unclear how breeding birds alter their behaviour in response to rapid climate change, and whether such plasticity will be sufficient to offset rising temperatures. We examine whether a small, open-cup nesting, passerine - the Jacky Winter Microeca fascinans - in semi-arid Australia, exhibits similar levels of behavioural plasticity when incubating under high temperatures as low, and how heat impacts upon parental effort, body mass change and reproductive success. At high temperatures, female effort increased. Females doubled nest attendance between 28 degrees C and 40 degrees C, switching from incubating to shading eggs at approx. 30 degrees C. Egg-shading females panted to avoid hyperthermia. Panting increased with temperature and sun exposure. Male breeding effort was linked to temperature extremes. In cold conditions, males provisioned their mates heavily, buffering females from additional energetic costs, and males suffered a loss of body mass. In extreme heat, males helped shade eggs (although they never incubated). The likelihood of male egg-shading increased with temperature, but level of contribution was positively related to sun exposure. Hatching success declined with air temperatures >35 degrees C. Egg mortality reached 100 at air temperatures >42.5 degrees C. Parents continued to attend unviable eggs (for up to two weeks), suggesting egg-loss from heat exposure is a recent phenomenon. Although pairs exhibited considerable behavioural plasticity - including positioning nests to maximize afternoon shade - this was insufficient to counter extreme temperatures. In 2019, one hot day (45 degrees C) effectively terminated reproduction two months early, and was associated with a 50% decrease in reproductive success. The increasing frequency, intensity and earlier arrival of extreme heat events is likely to pose a major threat to avifauna populations in hot, arid environments, due to increased parental costs, reduced reproductive success and direct mortality.

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