Differential advancement of breeding phenology in response to climate may alter staggered breeding among sympatric pygoscelid penguins

Abstract

Numerous studies link climate change with advancing breeding phenology in birds, but less frequently considered are the joint impacts on sympatrically breeding communities of birds. We used data on clutch initiation dates (CID) from 4 sites along the Western Antarctic Peninsula for 3 congeneric and sympatrically breeding penguin species (Adélie Pygoscelis adeliae, gentoo P. papua and chinstrap P. antarcticus) to understand what factors correlate with the phenology and synchrony of breeding and how these factors might change with the recent warming experienced in this region. We found that clutch initiation was most significantly correlated with October air temperatures such that all 3 species advanced clutch initiation to varying degrees in warmer years. Gentoo penguins were able to advance CID almost twice as much (3.2 d °C-1) as Adélie (1.7 d °C-1) and chinstrap penguins (1.8 d °C-1). Beyond the variation explained by mean October temperatures, there was an unexplained trend to earlier clutch initiation of 0.15 ± 0.05 d yr-1. Greater plasticity in gentoo breeding phenology compressed the mean interval between Adélie and gentoo breeding in warm years and this may increase competition for nesting space in mixed colonies. Our results suggest that differential responses in breeding phenology to changing temperatures represent an additional mechanism by which climate change may affect competitive interactions and, consequently, pygoscelid penguins on the Antarctic Peninsula. © Inter-Research 2012.