Brooklyn CNN  — 

Tourists are often warned in New York City not to stop and look up. But on one street where a tree grows in Brooklyn, looking up is encouraged.

You might just catch a rare sight in the bustling big city: beautiful green Quaker parrots, also known as monk parakeets. (They are hard to find, rarer than spotting Tony Danza strolling down Broadway.)

These birds have a back story that a little birdie might chirp to you if you’re lucky: They are believed to have their origins in Argentina, some 5,300 miles away as the crow flies. (Parrots, though, not crows.) These parrots didn’t travel that route, however.

The Birdman of Brooklyn

Steve Baldwin is our parakeet expert – I call him the Birdman of Brooklyn – and he is hooked on these wild, green birds.

“I’m one of the people who has taken an interest in the fact that the birds, who really don’t belong here, are here,” Baldwin tells me.

“I was charmed as a youth when my family brought a parrot into the household. We were all impressed with how emotional, engaging and endearing it was. So, I have a soft spot in my heart for these birds.”

Meeting his guests at Brooklyn College, Baldwin has been giving free Saturday morning tours to see the parrots for the past 12 years.

It takes a few minutes to stroll to a large tree with multiple nests in the branches, which the parrots have struggled to construct.

The unpredictability of the tour highlight – the birds actually showing up – means this tour is probably best for devout bird-lovers or curiosity-seekers who are looking for offbeat adventures.

How did the parrots get to Brooklyn?

Bird investigators and newspaper reports claim that these birds were descendants of parrots who broke out of containers and cages at John F. Kennedy International Airport in neighboring Queens. (I always thought the $6 million Lufthansa cargo robbery in 1978 was the biggest bust-out caper in the airport’s history, until now.)

But why were they at the airport in the first place? The main theory is that Argentina shipped thousands of birds in the 1960s and 1970s to the United States mainly to get rid of them, seeing them as agricultural nuisances.

They were sold in pet stores, owned by New Yorkers or turned into animal feed. Some of the parrots somehow broke out and escaped from the airport. Other parrots, according to theories, got away from broken crates at Newark Airport or were freed by owners who didn’t want them anymore.

The lucky escapees were not the migratory type. (After all, do you know how hard it is to find a good apartment or nest in the big city?) The current collection of Quaker parrots are believed to nest in a few New York locations, although not in the concrete jungle of Manhattan.

The tough streets of New York

It turns out these parrots have adapted to the city.

Instead of their country cousins, which have three toes in front and one in back, these New Yorkers have two in front and two in back, forming what Baldwin describes as a fist.

Baldwin says the birds seem to enjoy Brooklyn, despite the clamor of the subways and gentrified hipster cafes. (A lack of predators, such as hawks and owls, provide a sense of security for the birds.)

They feel so at home, Baldwin has spotted them eating a slice of pizza in the trees. It’s reminiscent of the New York City rat eating a slice, but not so gross. Brooklyn does have some of the city’s finest pizza parlors, though owners don’t expect the product to be eaten at such heights.

On a recent Saturday tour, about 15 people joined Baldwin as he explained the almost fable-like tale of the great parrot escape from the airport. The walking tours are a labor of love by Baldwin, a copywriter by trade, who says he was “charmed” by parrots once his father brought a bird home when he was a youngster.

Baldwin eventually led his guests to a large tree to see his favorite Brooklynites, where on this day three big nests were easily visible.

Amid the chirping, Baldwin whipped out his binoculars and observed the parrots, explaining how they used to have one huge nest. One day back in 2014, it came tumbling down and killed a bird.

Since that fateful day, Baldwin said the birds seem to understand now it’s better to play it safe and distribute their weight with three nests.

Nearby residents seem to appreciate their avian neighbors, calling them “cool” and “nice.”

These parrots issued loud greetings to each other but they did not appear to sing “Don’t Cry for Me, Argentina”, their ancestral homeland. These wild Quaker parrots seem content in the trees of Brooklyn and welcome all birdwatchers.

Check Baldwin’s website, Brooklynparrots.com, for more information about the parrots and tours.

CNN’s Lawrence Crook and Evan Simko-Bednarski contributed to this report