Against the odds, the little battlers of the Derwent, its penguins, are maintaining a flipper-hold in what has been their home for millennia.
On a cruise around the river and wider estuary in mid-August I was pleasantly surprised to count several rafts of little penguins on open water stretching from the shores of Tranmere to the south, to within sight of the zinc factory to the north.
The convenor of BIrdLife Tasmania, Eric Woehler, confirms that the penguins appear to be holding their own despite all the trials and tribulations that make life difficult in an environment increasingly shaped by mankind. These include frequent attacks by dogs on beaches where the penguins have their burrows.
It comes as a surprise to many people when I mention it is possible to see penguins in the Derwent. Colonies and individual burrows are kept a closely guarded secret but I know of one set of burrows within a few minutes of the Hobart town centre.
Habitat loss, or the loss of quiet, undisturbed breaches where nesting burrows can be located above the tide line, is also a major reason for penguin decline over the past 30 to 50 years. Another major threat is the use of catch-all, unattended fishing nets which in other parts of the country are banned. These nets anchored in such places as rock pools present a death trap not only for penguins but other seabirds like cormorants.
Penguins might be a vital component of Tasmania’s tourism attraction but some selfish and uncaring tourists have had an unfortunate impact on penguin numbers, not so much in the Derwent but on Bruny Island where there is still a sizeable little penguin population.
At penguin viewing sites on the Neck linking north and south Bruny island tourists have been seen digging penguin chicks out of borrows so they can feature in “selfies” from the Apple Isle.
Dr Woehler said that he suspected that most of the birds I had seen from the deck of the Odalisque tourist vessel – resting up in the Derwent out of season from its regular operation at Port Davey in the south-west – were “prospecting” birds swimming the Derwent looking for nesting sites.
“We have birds in burrows at the moment and I was on Bruny Island in mid-August, at the Neck, and there was plenty of evidence of penguins ashore,” he said.
Birdlife Tasmania – which has been compiling avian population and breeding records for half a century – has also seen a shift in the breeding phenology of penguins in south-east Tasmania.
“The old paradigm of spring arrival, summer breeding and autumn moult is long gone,” Dr Woehler said. “Now we are seeing winter and late winter occupation and occasional breeding, late spring and early summer breeding and even late summer and early autumn breeding, then moult.”
He said penguin breeding in Tasmania was increasingly meshing with the nesting period of mainland colonies where water temperatures were higher.
It all raises the question of whether global warming if starting to have an impact on penguin behaviour in Tasmania, with unknown consequences.
Only time, and the careful monitoring of Derwent penguin numbers, will tell.