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Abstract
We live in a time of increased awareness of the potential effects of climate on our ecosystems. The population of Little Penguins Eudyptula minor on Phillip Island, Victoria, in south eastern Australia is one such ecosystem. Not only does this Little Penguin colony provide valuable ongoing data for ornithological research, the nightly Penguin Parade is one of Australia s most popular tourist attractions. Research into the effects of climatic and oceanographic factors on the penguins health ensures that practices are put in place so that the colony continues to thrive.
In this study, I investigate the effect of wind on the survival of first-year and adult penguins. I use existing penguin life-history data for 54 484 birds, gathered over a 42-year period from 1968 to 2009, which makes this an extremely rare and valuable dataset for a single species. Wind data were obtained from Laverton RAAF Base in Victoria over the same time period.
I use a mark-recapture analysis of the summarised yearly data, and model age dependence for the survival and recapture probabilities simultaneously. Biologically realistic age structures which reflect the penguins' life styles are applied, and I model the survival of first-year and adult penguins using various group covariates involving wind magnitude and direction.
My work is built around two key hypotheses: firstly that westerly winds bring cool nutrient-rich waters into the foraging grounds of the penguins and this has a positive flow-on effect on the penguins food source; secondly that strong winds cause turbulence and mixing in the water columns of the penguins foraging grounds and this can adversely affect the penguins foraging success, which in turn leads to a negative effect on their survival.
The most significant effect on survival of first-year penguins is that of autumnal winds. This is a treacherous time for inexperienced newly-fledged birds. In particular, an increasing number of days with strong westerly winds in autumn appear to have a negative effect on first-year survival. Adult survival is negatively affected by an increasing occurrence of high wind days in summer when they are feeding chicks and preparing for the moult.