COS 136-2 - Climate variability shapes pair-bond dynamics and life-history outcomes in a monogamous seabird

Background/Question/Methods

Many animals form long-term monogamous pair-bonds, and the disruption of a pair-bond (through either divorce or widowhood) can have significant consequences for individual vital rates and life-history outcomes. There may be an indirect link between pair-bond disruption and the environment mediated by changes in demographic rates since climate conditions affect population dynamics. However, few studies have linked climate variables to the causes and consequences of pair-bond disruption, let alone its impacts on individual life-history outcomes. With access to a unique individual-based long-term monitoring data set of a long-lived monogamous seabird, the snow petrel (Pagodroma nivea), we investigated how climatic variables affect pair-bond disruptions, and thus, life-history outcomes including life expectancy and lifetime breeding success. We developed a MultiEvent-Capture-Mark-Recapture (MECMR) model to estimate the vital rates and pair-bond disruption rate. Effects of multiple climate indices were tested as covariates in MECMR models. We used an Absorbing Markov Chains (AMC) framework incorporating pair-bond dynamics to explore the life-history outcomes under different climate scenarios.

Results/Conclusions

We found that sea ice extent predicts widowhood rates by affecting adult survival, and divorce rates by mediating reproductive processes. These effects on pair-bond disruption may be due to the higher costs in reproduction and pair-bond maintenance, and changes in phenology and physiological stress under unfavorable environmental conditions. With the AMC framework, we showed that individual life-history outcomes are sensitive to changes in climate indices, and challenging environmental conditions can lead to a significant reduction of life expectancy and life-history outcomes. Overall, our results suggest that climate-driven pair-bond disruption may reveal demographic consequences at a population level under global change.