Sex-specific behavioural and physiological responses of breeding Atlantic puffins Fratercula arctica and their chicks to fluctuating prey abundance

Fitzsimmons, Michelle Grace (2018) Sex-specific behavioural and physiological responses of breeding Atlantic puffins Fratercula arctica and their chicks to fluctuating prey abundance. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The Witless Bay Ecological Reserve in Newfoundland and Labrador is home to the largest breeding colony of Atlantic puffins Fratercula arctica in North America. Studying parental investment over several years of fluctuating prey abundance, in combination with experimental food supplementation studies, can help determine how puffins are adjusting to ecosystem changes and can reveal the potential consequences of these changes for long-term survival and reproductive success. Puffins adopt a conservative breeding strategy such that parents need to balance their own survival and self-maintenance with parental investment, which is more challenging when food resources are low. First, how variation in resources affects chick growth and physiology was investigated. Food supplemented chicks had higher mass gain than controls, as well as higher rates of structural growth, a result previously seen only under the poorest feeding conditions. Second, audiovisual recordings and Passive Integrated Transponder tags were used to identify sex differences in parental provisioning effort, revealing that females provisioned chicks more frequently than males when food resources were low. Third, several physiological measurements were taken to determine the potential fitness consequences of parents to changing food availability. Female parents with chicks that were not food supplemented had higher beta-hydroxybutyrate levels, and indication of fasting, than both control males and adults with food supplemented chicks. These findings support the hypothesis that females invest more effort in provisioning and indicating that energetic demands of chick rearing may be greater for females than for males. Fourth, whether chick behaviour can influence parental provisioning was investigated. Chicks produced screech calls to inform parents of their hunger levels and screech calls were reduced after food supplementation. Parents did not return to the burrow with food quicker when screech calls were produced during the previous visit, as a parent’s response was limited by food availability. The behavioural and physiological responses to variations in food availability have demonstrated the ability of parents to adjust to changing environmental conditions while balancing self-maintenance and reproductive success. Puffins in this study population have successfully endured deteriorating foraging conditions; however, long-term shortages and mismatches in prey availability during chick rearing could potentially impact future populations, as observed in declining European colonies.

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