Age-specific nest-site preference and success in eiders

Area of Science:

• Ecology
• Behavioral Ecology
• Avian Biology

Background:

• Nest concealment is crucial for reproductive success, yet its variation poses an evolutionary puzzle.
• Trade-offs between nest safety and predator escape may influence nest site selection.

Purpose of the Study:

• To investigate the trade-off between nest concealment and predator escape in eiders (Somateria mollissima).
• To examine how breeder age and body condition affect nest site selection and success.

Main Methods:

• Assessed nest concealment, escape possibilities, and microhabitat preferences in eiders.
• Analyzed female capture rates, egg predation, and overall nest success in relation to nest characteristics.
• Correlated nest success with breeder age and body condition, controlling for nest centrality.

Main Results:

• Nest concealment negatively correlated with escape routes; higher cover increased female vulnerability during researcher capture.
• Open nests had smaller clutch sizes, indicating higher partial clutch predation, while experienced breeders had larger clutches.
• Nest success was independent of habitat but positively linked to breeder experience and negatively to hatching date.

Conclusions:

• Experienced female eiders select more concealed, central nests without compromising escape.
• Age-specific nest site preferences are driven by improved site selection and differential survival, not declining reproductive value.
• Individual learning and survival advantages explain age-related nest site choices in eiders.