Long-term breeding phenology shift in royal penguins

• Published in: Ecology and Evolution
• Main Authors: Hindell, MA, Bradshaw, CJA, Brook, BW, Fordham, DA, Kerry, K, Hull, C, McMahon, CR
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2012
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; The Antarctic; Antarc*; Antarctica; Macquarie Island; Sea ice
• Online Access: https://doi.org/10.1002/ece3.281; http://ecite.utas.edu.au/83694

The Earths climate is undergoing rapid warming, unprecedented in recent times,which is driving shifts in the distribution and phenology of many plants and animals.Quantifying changes in breeding phenology is important for understandinghow populations respond to these changes. While data on shifts in phenology arecommon for Northern Hemisphere species (especially birds), there is a dearth ofevidence from the Southern Hemisphere, and even fewer data available from themarine environment. Surface air temperatures at Macquarie Island have increasedby 0.62C during the 30-year study period (0.21C decade −1 ) and royal penguins( Eudyptes schlegeli ) commenced egg laying on average three days earlier in the1990s than during the 1960s. This contrasts with other studies of Southern Oceanseabirds; five of nine species are now breeding on average 2.1 days later than duringthe 1950s. Despite the different direction of these trends, they can be explained by asingle underlying mechanism: resource availability. There was a negative relationshipbetween the Southern Annular Mode (SAM) and median laying date of royalpenguins, such that low-productivity (low SAM) years delayed laying date. This accordswith the observations of other seabird species from the Antarctic, where laterlaying dates were associated with lower sea ice and lower spring productivity. Theunifying factor underpinning phenological trends in eastern Antarctica is thereforeresource availability; as food becomes scarcer, birds breed later. These changes arenot uniform across the region, however, with resource increases in the subantarcticand decreases in eastern Antarctica.