When Crawley resident Brad Power first discovered a pair of peregrine falcons on his 15th floor balcony, he knew something special was happening.

Key points: The tall apartment building replicates a cliff face, making a perfect habitat for the birds

The tall apartment building replicates a cliff face, making a perfect habitat for the birds Peregrine falcons hold the record for the world's fastest animal, reaching speeds in excess of 300 kilometres per hour

Peregrine falcons hold the record for the world's fastest animal, reaching speeds in excess of 300 kilometres per hour It is believed just seven breeding pairs live in the Perth metropolitan area

"I was intrigued," he said.

"I knew virtually nothing, but surprisingly there were people in the building who had an interest in birds and were fascinated to know they were here.

"We realised we should disturb them as little as possible and encourage them to successfully breed."

That encouragement has worked, as the falcons have returned to their Crawley nesting site for a fourth straight year and are now rearing another clutch of three chicks.

The falcons monitor their chicks constantly, and are extremely aggressive towards perceived threats. ( ABC News: Hugh Sando )

Falcons protected after population loss

Mandy Bamford from Birdlife WA said the birds' choice of nest site was not surprising.

"For the birds a tall building is like a cliff face, which is what they use naturally," she said.

"So you're providing a perfect habitat for them."

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Peregrine falcons hold the record for the world's fastest animal, reaching speeds in excess of 300 kilometres per hour when they dive through the air for prey.

They have been protected in Australia since 1971, but before that suffered severe losses mainly due to use of the pesticide DDT by farmers.

Ms Bamford said despite their protected status, they were still susceptible to human interference.

"Things like rat poison get into the food chain and large predators like owls and birds of prey really do suffer — and many different species are at risk," she said.

Peregrines pair up for life and move over a large territory.

It is believed just seven breeding pairs live in the Perth metropolitan area.

Peregrine falcons are the fastest animals on the planet, reaching speeds of more than 300kph when they attack prey. ( ABC News: Hugh Sando )

Mr Power said the birds proved to be a significant attraction for the apartment complex.

"Oh yes it's great to have them here," he said.

"It's fascinating to watch them.

"We try and get neighbours to see them, and we try and give feedback to the people in the apartments."

Birds menace neighbouring residents

But there are negatives to the birds' presence.

They are highly protective of their young and menace residents on nearby balconies.

For some people that means their balconies are entirely off limits until the chicks leave the nest later in the year.

"So that's three Christmas parties we've had to cancel," Mr Power said.

The falcon chicks grow quickly, and take their first flight about seven weeks after hatching. ( Supplied: Brad Power )

The falcons also have poor table manners.

"The worst part is the clean-up afterward," Mr Power said.

"They eat a lot and they make a little bit of a mess."

Ms Bamford said while the birds may caused inconvenience, their presence should be seen as a blessing.

"There are very good reasons for human health to have biodiversity around us," she said.

"It's much healthier for people, not just for wildlife.

"If they're nesting on your balcony and if you can manage to leave them for those couple of months to let them breed and fly away then that's really fabulous."