Personality-specific carry-over effects on breeding.

Milena Cairo,Philip Bertrand,Sébastien Descamps,Lynne U. Sneddon,Stephanie M. Harris,Samantha C. Patrick

doi:10.1098/rspb.2020.2381

Abstract

Carry-over effects describe the phenomenon whereby an animal's previous conditions influence its subsequent performance. Carry-over effects are unlikely to affect individuals uniformly, but the factors modulating their strength are poorly known. Variation in the strength of carry-over effects may reflect individual differences in pace-of-life: slow-paced, shyly behaved individuals are thought to favour an allocation to self-maintenance over current reproduction, compared to their fast-paced, boldly behaved conspecifics (the pace-of-life syndrome hypothesis). Therefore, detectable carry-over effects on breeding should be weaker in bolder individuals, as they should maintain an allocation to reproduction irrespective of previous conditions, while shy individuals should experience stronger carry-over effects. We tested this prediction in black-legged kittiwakes breeding in Svalbard. Using miniature biologging devices, we measured non-breeding activity of kittiwakes and monitored their subsequent breeding performance. We report a number of negative carry-over effects of non-breeding activity on breeding, which were generally stronger in shyer individuals: more active winters were followed by later breeding phenology and poorer breeding performance in shy birds, but these effects were weaker or undetected in bolder individuals. Our study quantifies individual variability in the strength of carry-over effects on breeding and provides a mechanism explaining widespread differences in individual reproductive success.

Highlights

A fundamental challenge in ecology is understanding why individuals vary in breeding performance
This study is, to our knowledge, the first to investigate how carry-over effects are influenced by personality, and to demonstrate personality-specific carry-over effects
Interactions between boldness and non-breeding activity supported personality-dependent carry-over effects, and in all supported interactions, we found that negative carry-over effects were stronger in shy individuals than in bolder individuals

Summary

Introduction

A fundamental challenge in ecology is understanding why individuals vary in breeding performance. As kittiwakes are sexually monomorphic and exhibit biparental care [35], we did not expect strong differences between the sexes, but expected that in line with other studies, carry-over effects on the timing of breeding may be stronger in females owing to greater control over egg laying. Following [39,40], we fitted a linear model with PC1 as the response variable, and individual identity (ID), test date, breeding stage and test number as fixed effects. 3.5.1 [46] using the lme package [47] for fitting linear mixed-effects models (LMMs.) Prior to testing for carry-over effects on breeding, we first determined whether kittiwakes varied in their non-breeding activity with boldness and sex. Parameter estimates from the conservative data subset were similar to those from the full dataset in both strength and direction, and are presented in Appendix F of the electronic supplementary material

Results

Findings

Discussion