Penguin populations in new fight for survival on Macquarie Island – ABC News


Penguin populations in new fight for survival on Macquarie Island
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The trio of rusting, iron boilers near the shoreline serve as a grim reminder of the slaughter of millions of penguins on the small Antarctic island of Macquarie, half way between Tasmania and Antarctica.
Humans used to harvest Macquarie Island penguins for their oil, with iron barrels — into which the birds were crammed and boiled alive — still visible on the beach
After almost being wiped out more than 100 years ago, the island's king penguin population rebounded
Researchers say despite that, surveys since 2007 show bird numbers are decreasing
When seal numbers dwindled after voracious hunting in the mid-1840s, the focus turned to penguins, which could produce an average of half a litre of oil each.
Thousands of penguins were sent to boilers every day so their oil could be extracted and burned in street lamps in cities far away.
The island was declared a wildlife sanctuary in 1933, with the king penguin population making a comeback, but a new study has researchers worried they may face another existential threat. 
The Tasmania Parks and Wildlife Service with support from the Australian Antarctic Division has been conducting an annual census of king penguin chicks on Macquarie island since 2007. 
Using this data, the Institute for Marine and Antarctic Studies (IMAS) has found the number of chicks is no longer increasing at the rate seen during the latter half of the 20th century.
"Instead, numbers have started to gradually decrease since the annual censusing began in 2007," IMAS PhD candidate and lead author Penny Pascoe said. 
"That could either mean the island has reached a carrying capacity or it could mean the population is in decline."
Researchers say there could be a number of factors, with climate change among them. 
They have found a large variation in chick numbers from one year to the next and have been able to link it with environmental changes on Macquarie Island. 
"We found that years with lower chick numbers were correlated with higher rainfall events and wave height during incubation, along with more storm events and warmer sea surface temperatures," Ms Pascoe said.
The Bureau of Meteorology climate statistics show temperatures rose to 17 degrees Celsius on Macquarie Island in February 2022 — the hottest recorded and around three degrees higher than the previous record. 
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"These changes are a worry for some of the species on the island because they are reliant on that island to come ashore and breed, as well as the food resources in that area," IMAS researcher and co-author Dr Julie McInnes said.
"So going forward it is important for us to monitor these populations and look at what's driving these changes, and determine whether is it climate change or something else we don't know about."
Macquarie Island is home to around 10 per cent of the world's king penguin breeding pairs and is the only breeding ground for the species in the pacific sector of the southern ocean. 
The island also hosts three other penguin species — the gentoo penguins, rockhopper penguins and the royal penguins, which are only found on the small Antarctic island. 
"Unfortunately we have seen the number of gentoo penguin breeding pairs have halved on the island in the past twenty years which is a worry and we are looking at what is driving that population change," Dr McInnes said.
"Globally, the rockhopper penguin population is declining as well and royal penguins are only found on Macquarie Island."
But there are concerns this population decline could have a wider impact on marine life, including killer whales which prey on penguins. 
"We have to remember the marine ecosystem is interconnected and if we take away one species it can have flow on effect to other species, whether that's the predators or the prey," Dr McInnes said. 
"The vegetation could also suffer if penguin populations continue to decline because their droppings bring important nutrients to the island." 
For the past 14 years, rangers have taken photos of every king penguin colony on the island in the month of August, which researchers then use to count every single chick. 
The chicks are brown and fluffy, compared to the adult king penguins which are black and white and look like they are wearing a slick dinner suit. 
"We spend many hours on the computer clicking dots on the penguins to count them, with the whole process taking several weeks," Ms Pascoe said. 
"You become very good at seeing what's a bottom, what's a head and what's a beak sticking out," Dr McInnes said. 
But researchers are now looking at what technology could be used to improve data collection.
"Drones are a potential technique going forward, as well as artificial intelligence or machine learning to try and count some of these chicks and integrate this with the long-term data set," Dr McInnes said. 
"But when you're on the island and you're standing over the penguin colonies and seeing and listening to them … there is nothing more special than that." 
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