Abstract
The largest colony of Little Penguins in Western Australia is located on Penguin Island, 50 km south of Perth, and the breeding performance of a nestbox subpopulation has been monitored for over 20 years. From our long term data set, high SSTs in April and May, both offshore and close to the colony, are correlated with fewer chicks per pair and lower masses of chicks at fledging. In the summer of 2010 and throughout 2011, the waters along the south-western coast of Western Australia were impacted by a record strength Leeuwin Current and above average sea surface temperatures. In 2011, the penguins breeding participation and success were the lowest observed since monitoring began. Less than a third of the average number of eggs was laid and only 10% of these resulted in successful fledglings. In addition, four times the average number of penguins was found dead from August-December 2011. The dead penguins were found on Penguin Island and along the coast, up to 400 km south of the colony. Autopsies revealed that many of the penguins had died from starvation. Diet composition studies revealed that whitebait, Hyperlophus vittatus, the major constituent of their diet in previous years, was absent in 2011. It is likely that the anomalous oceanographic conditions impacted the presence of the whitebait in the local coastal waters. However the construction of a boat ramp adjacent to the major whitebait nursery in 2010 may have also played a role. These data highlight the ability to use penguins as sentinels of climate change but also the difficulty in decoupling environmental and anthropogenic causes of change. The next step is to determine how resilient both the coastal ecosystem and this genetically distinct penguin colony are.