Assistant Professor of Biology Bowdoin College, United States
Background/Question/Methods
Increasing reproductive success with age has been demonstrated in a range of wild bird, mammal, and insect populations. Little is known about the specific physiological and behavioral factors that underlie these patterns of reproductive success. Egg volume and lay date are quantifiable reproductive parameters, making them ideal for understanding these questions. We used a unique dataset that tracked individuals over an 18-year period to investigate patterns in egg volume and breeding phenology in a population Leach’s storm-petrels, Hydrobates leucorhous, a long-lived procellariiform seabird on Kent Island in New Brunswick.
Results/Conclusions
We found that lay date is strongly affected by pair-bond duration, with pairs that mated together in the previous year laying earlier than pairs that did not, and lay date continuing to move earlier over longer pair bond durations. Egg volume was not affected by pair-bond duration but was affected by spring sea-surface temperature, a critical time period when females are building resources for egg production. We propose that the patterns of increasing reproductive success with age in Leach's storm-petrels are driven predominantly by increasing pair coordination over time.
