For more than three decades, Melbourne’s famed Collins Street peregrine falcons have treated a CBD skyscraper ledge as home.
Now, the cameras that made them a social media phenomenon are again rolling for a new breeding season, with the first egg laid this week.
There are high hopes for this season. Last year’s eggs were unable to hatch after the female stopped incubating, likely due to a territorial dispute.
Dr Victor Hurley, the lead researcher of the Victorian Peregrine Project with BirdLife Australia, told Guardian Australia that a different female falcon had taken up the nest on the ledge of the Collins Street skyscraper this year.
“The markings are a little bit different on the chest. So I think it’s a different individual that is starting breeding a bit older,” he said.
“Hopefully she’ll also be able to hold ground if another one tries to usurp her.
“We’ve got a recovering population. That is what’s going on in these areas. When that happens, you get competition for sites because they’re so territorial. They won’t tolerate anybody – they make lousy neighbours.”
About 400 users were watching the live stream as of Tuesday afternoon.
Hurley first noted falcons trying – without success – to raise eggs in a metal rain gutter on a city building back in 1991.
In 1992, he placed a wooden tray with some sand on a high-up window ledge – and since then the birds have returned annually to the office tower near the corner of Queen and Collins streets.
During Covid lockdowns, thousands of house-bound people tuned in to a 24-hour webcam stream of the nest and the building’s own website every day.
Almost 50,000 birdwatchers have flocked to a Facebook group dedicated to the birds called “367 Collins Falcon Watchers”.
Hurley said up to four eggs could be expected each breeding season.
In the beginning, he said, the male and female falcons could be “quite inattentive” and would not be sitting on the eggs for many hours of the day.
“It’s the same behaviour up until the second last egg. So what they’re doing is they’re delaying the development of the first two to three eggs,” he said.
“Once they warm them back up to about 38 degrees, then you’ll find the series of biochemical dominoes start falling and creating this pathway to creating the embryo can’t be stopped.”
He said if chicks hatched too far apart, the larger ones would start dominating the food.
Once the last egg was laid, Hurley said, hatching could be expected in about 32 days.
“If it’s really cold it can take a bit longer – up to 40 days – and if it’s nice and warm and everything, then they could be all done by 28-29 days.”
