Wednesday, July 1, 2015

St Kilda’s penguins find the Yarra River a tasty treat

A study has found the Yarra River is a feeding hot spot for Melbourne’s penguins.
A study has found the Yarra River is a feeding hot spot for Melbourne’s penguins.
THE Yarra River is considered muddy, brown and awash with E coli, but new research casts a different light on Melbourne’s often derided waterway. 
A study tracing the feeding patterns of St Kilda’s colony of little penguins suggests the Yarra mouth is a feeding hot spot for the loveable birds. “Nutrients like phosphorus are pushed down the river towards the bay, attracting anchovies and pilchards, which are key prey items for penguins,” explains Monash University PhD student and lead researcher, Nicole Kowalczyk.

Forty four of the 1000-strong St Kilda penguin colony were GPS tagged, and their movements recorded between 2008 and 2012.

Findings for the study, published this week, showed when the river was at its highest in 2010 after the drought broke, there was a 50-fold increase in nutrient levels in the bay.

And equally, in drought years when river outflow fell, the penguins foraged closer to the river mouth to eat the fish chasing a paucity of nutrients. “They’re a hardy bunch, so versatile and very flexible,” Ms Kowalczyk said.

The team of researchers, in collaboration with Earthcare St Kilda and Phillip Island Nature Parks, also collected data from the Spirit of Tasmania, which records water temperature, clarity and chlorophyll content across the entire bay at regular intervals.

Ms Kowalczyk found the penguins’ GPS tracks regularly overlapped with the shipping channel, however she said limitations in her study made it difficult to assess whether this was simply a coincidence, or an indication that penguins preferred to hunt in clearer water. “Melbourne is pretty proud of their penguin population and we just wanted to find out where they were feeding and why,” she said.


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