Moderators: Belinda Cannell (School of Biological Sciences and Oceans Institute UWA), Ed Cripps (Department of Mathematics and Statistics UWA).

The Little Penguin colony on Penguin Island, 50 km south of Perth, is at the northern range edge of their distribution. The colony is facing mounting pressure from several factors, including climate driven changes in food availability, increasing land temperatures, interactions with watercraft. The severe Marine Heatwave in 2011 is a case in point- the diet composition changed, many penguins died from starvation, and breeding outcomes were poor during and in some years following the heatwave. The population has also markedly declined since the heatwave. Using RF modelling, we found relationships between breeding success and SST in April, mean winter Fremantle Sea level, greater variance in SOI  and less variance in April SST.

Colonies are also found on islands in southwest and southern WA, but  very little is known about most of them. 

We have been collecting data and studying the ecology of the Little Penguins  on Penguin Island for almost 40 years, including data on their foraging habitat, breeding success and causes of mortality. 

In 1994, the Dawesville Cut was constructed, between the Peel-Harvey estuary and the Indian Ocean. This allowed sea water to flow in and out of the estuary, removing the build-up of algae. However, it could also potentially move nutrients further south of the Cut during rainfall events, which may results in penguin fish prey moving further south too. This would potentially result in the prey being outside the critical foraging habitat of the penguins while they are raising chicks, i.e. within 30 km of the colony.

Additionally, oceanographic warming, and especially sea surface temperatures, are likely to affect the abundance of fish species and thus the food supply and breeding success of the Little Penguins. It may be that some predictions can be made concerning  sea surface temperature changes and fish species response  under climate change.  

The  objective of the MISG will be to assess the impact of the Dawesville cut and climate change on the population of the Penguin Island colony. One might hope that the available data will be sufficient to identify the important factors affecting colony population changes. Optimistically one might hope to then develop dynamic models that could be used to determine the changes in population size under various climate change scenarios. 

References:

Cannell BL, Chambers LE, Wooller RD, Bradley JS (2012) Poorer breeding by little penguins near Perth, Western Australia is correlated with above average sea surface temperatures and a stronger Leeuwin Current. Mar Freshw Res 63: 914−925.

Cannell, B. L., Campbell, K., Fitzgerald, L., Lewis, J. A., Baran, I. J., & Stephens, N. S. (2016). Anthropogenic trauma is the most prevalent cause of mortality in Little Penguins, Eudyptula minor, in Perth, Western Australia. Emu-Austral Ornithology, 116(1), 52-61.

Cannell, B. L., Kendall, W. L., Tyne, J. A., Bunce, M., Hetzel, Y., Murray, D., & Radford, B. (2024). Marine heatwaves affect breeding, diet and population size but not body condition of a range-edge little penguin colony. Marine Ecology Progress Series. 737: 193-213.