COS 77-1 - Personality as a driver of population dynamics in a long-lived seabird

Background/Question/Methods

Differences among individuals within a population are ubiquitous. Those differences can be due to age, sex, or any phenotypic trait. Accounting for those differences, which are structuring elements in a population, is necessary to understand the dynamics of populations. Personality, owing to its typical large within-population variability, can represent an important phenotypic trait structuring populations and driving population dynamics. We have evidence that personality can generate individual differences in reproductive rates, with bolder individuals typically having higher reproductive success. However, risk-prone bolder individuals may suffer from higher mortality. Therefore, the relative and combined effects of personality on all vital rates, life-history outcomes, and its overall impact on population dynamics remain to be assessed. Here, based on a unique dataset on demography (55 years) and personality (11 years) on the wandering albatross (Diomedea exulans) at Crozet, we first tested the relationships between boldness, survival rates of adults, breeding probability and breeding success using Bayesian Capture-Mark-Recapture models. Then, we investigated the relationship between personality and individual fitness, proxied by lifespan and lifetime reproductive success, using Principal Components Analyses. Finally, we built a hyperstate matrix population model and conducted sensitivity analyses to quantify the impact of boldness on population growth rate.

Results/Conclusions

We found that boldness affected annual reproductive rates in the wandering albatross. The probability of breeding was higher for bolder adult females, but no such relationship was found in adult males. Bolder adult females and males also had a higher success in raising their chicks and the relationship was stronger for adult females. We found weak evidence of a negative effect of boldness on adult survival. Over the lifetime of individuals, boldness was associated with higher lifetime reproductive success, but reduced lifespan for both males and females. Our results suggest that bolder individuals may be more efficient in acquiring food resources and securing reproduction but may also suffer from a greater cost of reproduction or higher vulnerability to mortality causes such as fishery bycatch. Overall, population growth rate was sensitive to changes in the distribution of boldness scores within the population, and evolutionary changes in boldness could have implications for the long-term population trajectory of wandering albatrosses. Our results suggest that personality can act as a driver of population dynamics in wild animal populations.