The falcons have been laying eggs at 367 Collins Street for more than 30 years, attracting a massive following on social media after a webcam was introduced to stream their activities in 2016.

Victorian Peregrine Project founder Doctor Victor Hurley said while they had expected the male to have already fledged, all the hatchings — three female and one male — were looking strong and healthy.

"The male is running a bit late … but he still hasn't flown yet, and the first of the females is not expected to fly until over the next two days," he said.

All four of the eggs laid hatched despite the female being forced to spend additional time away from the nest hunting for herself after her then-partner — and the chicks' father — became entangled in a love triangle after another male came onto the scene.

Dramatic scenes unfolding during the incubation period eventually saw the chicks' father, known as Dive-bomb Dad, booted out of the nest.

The chicks' step dad at first seemed disinterested, but Dr Hurley said the male's parenting instincts kicked in as the eggs started to hatch.

The original male has not been spotted since September and Dr Hurley said it had likely died.

No flight, no food:

Under the care of their mother and step dad, the hatchlings have thrived and were preparing to launch off the 34-storey building for the first time.

"The adults have reduced the amount of feeds down to about two a day, and we think that's a deliberate strategy to encourage the young ones to fly," Dr Hurley said.

"It's some Homer Simpson level of thinking going on, 'I'm hungry. I like food. Parents are flying with food. Food comes from the sky. I better get flying'."

A lighter body weight — due to reduced feed — would also assist their efforts to fly.

"Their body is getting lighter, so it will be easier for them to fly in the next few days as they lose a bit of weight," Dr Hurley said.

"They have feathers that are still growing. Their flight feathers are getting longer so they're getting longer wings.

"Everything's geared towards that first flight."

Dr Hurley said the parents would also be flying around the nest with food to encourage the hatchlings to fly.

Hunting skills fine-tuned

While their first flight is expected at any minute, the hatchlings will hang around until late as January next year while they fine-tune their hunting skills.

"The adults will first drop dead birds from the sky to a young one that's already flying and encourage them to catch it," Dr Hurley said.

"That's the initial training, like training wheels on a young kid's bike."

What's next for empty nesters?

Dr Hurley said after the birds had flown off, he would be tasked with cleaning up the nest, which is made of rocks in specially constructed boxes.

The building's owner, Mirvac, was also planning to install a second camera to give nearly 50,000 Facebook fans double the action.

"The camera can only face in one direction at any given time, and every time we move it, it does distract and heighten the attention of the birds," Dr Hurley said.

While virtual twitchers might struggle to catch the first flight of all four birds, Dr Hurley said the birds would be undertaking plenty of practise over the following weeks for enthusiasts to watch.

Original St0ory By | Zilla Gordon