High temperatures drive offspring mortality in a cooperatively breeding bird

Area of Science:

• Ecology
• Climate Change Biology
• Animal Behavior

Background:

• Understanding life-history adaptations to environmental variability is crucial for predicting species' responses to climate change.
• Cooperative breeding systems may offer a buffer against unpredictable climatic conditions for individuals.
• The southern pied babbler (Turdoides bicolor) is a cooperative breeding bird inhabiting arid zones.

Purpose of the Study:

• To investigate the correlation between environmental conditions, group size, and the survival of young southern pied babblers across three developmental stages (egg, nestling, fledgling).
• To determine if larger group sizes mitigate the negative effects of adverse environmental conditions on offspring survival.

Main Methods:

• Utilized a 15-year dataset on the southern pied babbler (Turdoides bicolor).
• Analyzed survival probabilities of young during egg, nestling, and fledgling stages.
• Correlated survival rates with environmental factors, specifically mean daily maximum temperatures (mean Tmax), and group size.

Main Results:

• High mean daily maximum temperatures (mean Tmax) during early development were significantly associated with reduced survival probabilities for young birds at all stages.
• Zero survival of young was observed when mean Tmax exceeded 38°C, irrespective of group size.
• Increased group size did not moderate the negative impact of high temperatures on the survival of young.

Conclusions:

• Elevated temperatures pose a significant threat to avian recruitment and population persistence, particularly in the context of rapid climate change.
• Cooperative breeding, as observed in southern pied babblers, does not appear to buffer offspring against the detrimental effects of increasing temperatures.
• These findings highlight the vulnerability of avian populations to climate change and the limitations of social buffering in extreme heat events.