Robert Riddle first became aware of the phenomena a year ago as he was getting ready for bed. The crunching of leaves underfoot and the train’s whining arrival at a nearby station were the only interruptions to an otherwise still autumn evening.

Not long after Riddle’s head hit the pillow, he heard a cacophonous shriek. Realizing the wailing came from an apple tree behind his condominium, Riddle investigated and discovered the source of his insomnia.

“Wild Parrots,” Riddle calls them, though they are actually a flock of monk-parakeets who migrated, presumably, from somewhere in South America close to a decade ago.

Since arriving in North America, the monk parakeets have slowly migrated westward with sightings in New York, Canada and behind the Museum of Science and Industry in Hyde Park.

“I usually see them early in the morning and later in the evening,” says Riddle of the mysterious birds, which have quietly built several nests on the West Side, most notably in a tree at the corner of Mason and Madison.

Riddle, who lives at Washington and Austin, on the Oak Park side, has been observing the monk parakeets ever since that sleepless night nearly a year ago, and finds them to be a truly extraordinary in their ability to adapt to the often unforgiving Chicago area winters.

“They remain in their nests all year-round,” said Riddle. “The way they have been able to handle both the severe cold and oppressive heat of the environment is a beautiful thing.”

Doris Johanson, bird expert and public relations coordinator at the Chicago Audubon Society, also marvels at the parakeets’ incredible endurance.

“They are a very strong bird,” said Johanson. “I theorize they possibly once lived high in the frigid Andes, explaining their resistance to colder temperatures.”

According to Riddle, the birds can represent every color in the spectrum from green (allowing them to camouflage within the trees) to red or blue, giving them the appearance of the more popular parrot.

However, unlike their neon-colored distant cousins, monk parakeets are unlikely to repeat the babbling alliterations of human beings, do not have an insatiable craving for saltines, and prefer not to be confined in a bell shaped caged, which is to say, they are not housebroken.

“I wouldn’t imagine anyone wanting to inherit one of these birds as a pet,” said Johanson. “They squawk very loudly, which would make them difficult to keep. They also travel in several flocks of families, meaning that their loyalty to their colony may not allow them to be confined to a home away from their group.”

Aside from their propensity for stentorian shrieking, they are also messy birds, leaving their fair share of dropping beneath their nests. Riddle admits they “don’t use bird baths.” Nevertheless, they are a source of wonder for many who have observed them throughout the community.

“Many people in my condominium have group gatherings around the trees where the birds nest. It has been the source of much discussion throughout the building as my neighbors have tried to theorize where they came from. My wife loves them, too, even when they are shrieking,” said Riddle. “However, she tried to encourage me not to talk to the media about them because she was afraid it might attract rabid hunters looking to shoot them.