United States President Donald Trump might describe climate change as a “hoax” but rising temperatures are certainly having an impact on the environment across the world, including in Tasmania.
Tropical fish not usually found this far south are turning up in Tasmanian waters, little penguins are struggling to find fish that are vanishing from a warming ocean, and migratory birds are increasingly staying put instead of heading north in winter.
One migrant that is apparently showing a penchant to ride out the Tasmanian winter is the striated pardalote, which usually leaves the state in March, to return at the end of August.
Although late-departing pardalotes are sometimes recorded in April, this autumn abnormally high numbers of the species were still showing as late as mid-May.
A previous over-wintering event occurred during a mild summer in 2017. Now birdwatchers in the state have been urged to watch out for pardalotes and ensure they are entered in surveys.
The striated pardalotes are the only one of the three pardalotes found in Tasmania to migrate. The others are the spotted and forty-spotted pardalotes and the focus on the migratory species raises interesting questions. What dilemma faces these small, fragile birds – smaller than a sparrow – as autumn and winter looms? Should they stay or go? The stakes remain high, either way.
The research surrounding the Tasmanian pardalotes highlights the importance of bird surveys, a field of citizen science becoming increasingly popular with what can be described as weekend or casual birdwatchers. The surveys are usually conducted over a 20-minute period, covering a two-hectare site and are entered on Birdlife Australia’s Birdata portal.
Birdlife Tasmania’s Yellowthroat newsletter in May demonstrated the value of surveys when a graph of data analysed by member Mike Newman between 2018-24 was published.
The graph shows the peak times for straited pardalote activity in Tasmania, building after the birds arrive in August, and then being progressively recorded less frequently from January to March. The surveys also record a few birds remaining between April and July.
With a larger number of birds remaining in April this year, Mike Newman says it raises the question of whether pardalotes are migrating later, or if a larger proportion of the Tasmanian population is remaining this winter as happened eight years ago.
As with most migrating Tasmanian-bred birds, precise information on where they go after making the perilous journey across Bass Strait is still to be gathered but a clue to the wintering grounds was revealed a few years back when one was spotted in winter in central-west New South Wales.
The Tasmanian sub-species of striated pardalote carries a yellow mark on its wing feathers, whereas other pardalotes from across the country have a red one.
The yellow distinguishing feature revealed to the outback birders they had a visitor from Tassie in their midst.