Age-dependent phenological plasticity in a wild bird.

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Life-history traits exhibit plasticity in response to environmental factors and age.
• Age-dependent plasticity may influence trait variation throughout an organism's life.
• Phenological traits, such as egg-laying date, are crucial for reproductive success.

Purpose of the Study:

• To investigate age-dependent plasticity in egg-laying date in response to spring temperature.
• To determine if this plasticity varies with age in blue tits.
• To explore the relationship between age-dependent phenological plasticity and breeding success.

Main Methods:

• Utilized a four-decade long-term monitoring dataset of a wild blue tit population in Corsica.
• Estimated age-dependent plasticity of reproductive phenology (egg-laying date).
• Assessed annual reproductive success in relation to age and laying date.

Main Results:

• Both egg-laying date plasticity and annual reproductive success varied significantly with age.
• Young and old female blue tits exhibited less plasticity and lower fledging success compared to middle-aged females.
• In old females, fledging success was independent of egg-laying date, unlike in younger females.

Conclusions:

• Phenological plasticity is a key mechanism for adapting to environmental variability, including climate change.
• Age structure plays a critical role in population persistence and adaptation.
• Integrating age structure into studies of phenological plasticity is essential for understanding climate change impacts.