An avian battle in the heart of Melbourne’s CBD is threatening to unseat one of the city’s beloved peregrine falcons.
Every year, thousands of social media users eagerly watch a live stream of the cocky male bird and his partner raising chicks atop a Mirvac-owned skyscraper at 367 Collins Street.
This spring, a young rival is threatening to ruthlessly unseat him with what observers have called "Game of Thrones-style brutality".
Such a challenge is rare amongst the species, according to Victorian Peregrine Project founder Dr Victor Hurley who studies the pair.
When an earthquake rocked Melbourne in September 2021, many of the city’s human residents panicked. By contrast, the male falcon jumped from his ledge in an apparent effort to attack the source of the tremors.
"They're scared of nothing,” Dr Hurley Yahoo News Australia at the time.
Video of the male’s bold response was viewed millions of times, and the falcon’s social media following grew by thousands.
A normal beginning to falcon nesting season
Fans of the falcons' social media page were the first to notice the male exhibiting uncharacteristically timid behaviour this year, and were quick to alert Dr Hurley.
The male is easily identifiable by his swollen yellow eye-ring and he is believed to have reigned over his Collins Street realm since 2017.
During the last two weeks of August, he had been observed incubating the eggs as expected during daylight hours, while the larger female used her added bulk to keep them warm at night.
A fortnight ago, viewers of the live stream started reporting a rival was visiting their ledge and the male had stopped sitting on the nest.
“I think physically he feels vulnerable sitting down flat on this ledge because it wouldn’t be hard for the second male to take him out,” Dr Hurley said.
“He'll go up to the eggs. And he might literally sit down for 10 seconds and then he's up again and he's off, whereas last year he may have spent three hours incubating. This is very unusual.”
By September, the resident male had stopped bringing food to his mate.
“Normally he would bring food as a bribe to get her up so he can sit on the eggs,” Dr Hurley said.
“The older, more experienced males tend to be better at incubating.”
Male falcon attacked by the Yarra River
Dr Hurley has monitored peregrine falcons at 120 sites across Victoria for 30 years, and he doesn’t normally have time to study falcons in such depth.
On Friday, he received a report from one of the falcon’s Facebook page’s 37,000 followers saying he saw two males on the banks of the Yarra River near Federation Square "trying to kill each other".
“That was just a battle. But the war hasn't finished and when it does, one of them will be dead,” Dr Hurley said.
“This has a Game of Thrones air to it where they take no prisoners.
“At the moment, the males are avoiding each other on the nest ledge. That’s because the female is saying: You boys sort it out, it’s not my problem."
Will the eggs survive the young falcon’s takeover?
Should the male falcon be killed, the female will continue her incubation duties. The newcomer will be expected to start helping by sitting on the nest and providing the female with food.
Dr Hurley believes the young male would likely help the female raise the nestlings. That’s wouldn’t be out of chivalry but rather because successfully fledged chicks signal the nesting site to be strong for future breeding.
Should the eggs not survive incubation, the female will likely leave the site in search of new territory.
That’s because last year’s female mysteriously disappeared and is likely dead, meaning this is the current female's first season testing out the site.
“If you disappear from a nest, you’ve probably been killed by the incoming female,” Dr Hurley said.
“They just kill each other. So as I often say to people, peregrine falcons haven't evolved with the benefit of any influences from the French Enlightenment.
“We think their behaviour is cruel or inhuman and it is inhuman. That’s because they're not humans and have a different set of rules.
“There's not a lot of emotion involved. It's kind of like if you’ve got the resources to feed chicks into fledging then you’re the guy for me.”
What’s next for the two rival males?
The resident male falcon is believed to be around seven years old, while his challenger is likely three or four.
Dr Hurley believes the pair are evenly matched because, if he was able, the younger one would have killed his rival by now.
“It's only a matter of time when we're just going to stop seeing one of the males because the other one has been killed,” he said.
The falcon live stream can be found here.