Winter has been tough on the superb fairywren, with ACT populations suffering 50 to 70 per cent mortality. Photo: Olivia Congdon/ANU.
Canberra’s superb fairywren population has plummeted over winter, with 50 to 70 per cent thought to have perished.
The tiny wrens are a common sight in the ACT. The distinct blue plumage of the males makes them popular among local artists, photographers and bird watchers.
But the enigmatic little bird could be in trouble as extreme weather events cripple its population.
The birds are not currently considered endangered or threatened, but significant declines in their population in recent years have raised concerns among researchers.
“We had 72 adults and 39 chicks at the end of last summer. Of these, 37 adults died – or 51 per cent – and there are only six remaining chicks,” ANU Associate Professor Aiden Farine said.
The unexpected mortality was seen in a monitored population of wrens at the Australian National Botanic Gardens, where ANU researchers have been monitoring the population since the 1980s.
It’s a trend that’s been seen elsewhere in the territory. At Campbell Park, another monitored population lost 70 per cent.
Winter mortality is not unusual for the species, but according to Professor Farine, a loss of this size is something we haven’t seen before.
“It’s a big loss. To put it in perspective, in 1999, 2002, and 2003, we lost about 20 per cent of the adult birds, and those were exceptional years.
“It’s not just happening in one place. It’s as bad, if not worse, elsewhere.”
Superb fairywrens literally shiver themselves warm over winter, but when temperatures spike and drop unexpectedly, they often can’t cope. Photo Nicholas Ward.
What exactly is causing this population loss is, at the moment, a mystery. Researchers think the variability of winter plays a big part in it.
Mortality tends to spike after winter heatwaves have passed and cold weather returns.
“When suddenly it gets cold again, a couple of weeks after those heatwaves, that’s when it really bites, and that’s when they’re really suffering.
“It’s kind of this counterintuitive thing that weather getting warmer is actually making it worse for the birds.”
This last winter was especially bad, with June seeing some of the coldest nights in decades, followed by milder weather in July and August.
While the tiny birds do adapt to survive the cold – they shiver themselves warm overnight and sun themselves on sunny winter days – they can’t handle extreme weather variation.
According to Professor Farine, the effects of global warming may be playing a part in their ongoing decline.
“Global warming … it might make the winters warmer, but what it’s doing is it’s creating more extreme events and more extreme fluctuations.
“The fairywrens are very susceptible to this shift from the hot to the cold. And so with global warming, what we see is more winter heatwaves.”
Unfortunately, this winter is not a one-off for the wrens. Populations have been declining for years.
“[Their population] was already down by about 65 per cent when compared to the long-term size of this population, and now it’s crashing further.
“It is crazy to think that we might be seeing the population make its way towards extinction.”
The superb fairywren is not a threatened animal, but huge drops in population in recent years have many researchers concerned. Photo Nicholas Ward.
The work Professor Farine is engaged in through the ANU Research School of Biology has wider implications around Australia, where other woodland bird populations have been in steady decline for years.
The monitored fairywren populations at the Botanic Gardens were part of a research project established by Professor Andrew Cockburn in the late 1980s.
The research has helped us understand the birds and their ongoing decline.
Professor Farine took over the project in 2023. He had been studying bird populations in the UK, Europe, and Africa.
He said that soon after he began at the ANU, he saw how important Professor Cockburn’s work was.
“I saw that he was finishing up work on this, I thought, well, we can’t let this finish now, such an important asset to our ancient ecology and behaviour, and conservation of birds in Australia.
Since taking over the project, they have focused on behavioural strategies for survival in the birds.
Work like his is helping researchers understand why this population decline is happening and hopefully to prevent it.
“The data brings an important perspective on how changes in the climate over the winter are impacting our bird populations, and is something that we hope to study in much more detail over the coming years,” Professor Farine said.
