Environmentally driven sexual segregation in a marine top predator

Area of Science:

• Marine Ecology
• Animal Behaviour
• Conservation Biology

Background:

• Sexual segregation in foraging is common in animals but poorly understood.
• Resource partitioning reduces competition between sexes.
• Understanding drivers is crucial for conservation.

Purpose of the Study:

• Investigate patterns and drivers of sexual foraging segregation in Cory's shearwaters (Calonectris borealis).
• Determine how environmental stochasticity influences sex-specific foraging strategies.
• Assess the impact of foraging differences on body condition and breeding success.

Main Methods:

• GPS-tracking of foraging movements.
• Habitat modeling for habitat use analysis.
• Stable isotope analysis for trophic ecology.

Main Results:

• Clear sexual segregation in foraging observed in years with high environmental stochasticity (likely low food availability).
• Females undertook longer foraging trips, exploited more homogeneous waters, and had a larger isotopic niche.
• Females fed on lower trophic level prey and exhibited lower body condition compared to males.

Conclusions:

• Sexual competition for trophic resources intensifies during poor environmental conditions.
• Differential foraging success impacts pair mate body condition and parental effort.
• This can ultimately increase the probability of breeding failure in Cory's shearwaters.