Melbourne's famous peregrine falcons are giving their live stream followers something to squawk about, with two tiny chicks hatching and another on the way.

The daily antics of the raptors, which live on a ledge on the 35th floor of 367 Collins Street, have become a prime attraction for thousands of avid online followers — many who commentate every fluffy development via a 50,000-person strong dedicated Facebook group.

Wildlife ecologist and self-described "bird nerd" Victor Hurley voluntarily oversees the project, and said Thursday had been an exciting day for lovers of the birds of prey.

"So there were three eggs laid, two have hatched, and the third one has started, and will hatch today," Dr Hurley said late Thursday morning. "We'll see that live at some point."

Dr Hurley told the ABC's Sammy J that the first two chicks hatched about an hour apart early on Thursday morning — weighing only about 40 grams each — and the live stream showed a split down the third egg.

"It's almost like a zipper. It's already started to hatch out. It takes some time, but it will."

Keen observers — Dr Hurley for instance — spotted a small triangle of eggshell missing before sunset on Wednesday night.

"Then that didn't hatch until about five o'clock this morning," he said. "It's quite a lengthy process and pretty exhausting for them."

Since 1991, about six pairs of peregrine falcons – one pair at a time — have been observed living in a nest on a ledge of the Collins Street building.

Their fiercely territorial nature means that any other pair is excluded from nesting within about 1.5 kilometres, or pretty much the entire CBD, Dr Hurley said.

"There's a lot of competition for high quality sites."

In the early days a closed-circuit television camera relayed footage of the predators via coaxial cable to the skyscraper's foyer, and Dr Hurley would bring his TV in from home so people could watch along.

"About 20,000 people a year would wander through just to look ... school groups would go and everything," he said.

But Dr Hurley says the falcons, now seen via a more modern webcam, became particularly watchable during COVID-19 lockdowns.

"A lot of people really got involved, because our lives were kind of like four walls, and so this gave them something to focus on for a couple of months."

Melburnian Karen Leng is one of many wildlife lovers watching with fascination from home.

"I love studying and watching them. Just by observing their habitat, one can learn a lot about them," she said.

"Over the last five seasons, I have learned about their way of life, their interaction with each other, how they care for their young."

And it turns out the baby chicks have wasted no time in searching out a bite to eat, helpfully flown in by their father.

"They get fed almost within the hour of hatching, so their energy consumption needs start from day one," Dr Hurley said.

"They do have a small yolk sac that they do draw nutrients from as well. But the adults will also feed them."

However it will be some weeks yet before the baby birds take flight, which will be another time of great anticipation for the falcons' online followers.

Unlike most birds, female birds of prey are larger than their male paramours.

So that means the males will take their first flight off the ledge in about 35 days, while the females will likely take a week or so longer, Dr Hurley explained.

"So five to six weeks, they'll be all gone by mid-November."

And after that, Dr Hurley and the live stream will also take flight until breeding season next August.

"I switch it off because otherwise it's kind of like I'm moderating a group looking at feathers blowing in the wind," he laughed.