A member of the Prospect Park maintenance staff spotted the gator near Duck Island in Prospect Park Lake.
Officials said the rescue wasn't too difficult given the condition of the alligator and its proximity to the banks.
Search on for person who dumped 4-foot-long alligator in Brooklyn
The alligator, which New York City Parks Department officials said was lethargic, extremely emaciated and suffering from exposure to cold temperatures, is currently undergoing evaluation at the zoo by veterinarians and animal care staff.
The zoo said that the female alligator was "slowly warmed to an appropriate ambient temperature" and is receiving supportive care.
It's being tube-fed to provide her with nutrients and fluids because the alligator is currently too weak and unresponsive to eat on its own.
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"When the nearly five-foot alligator was brought to the zoo by the New York City Department of Parks and Recreation, it presented as extremely emaciated weighing only 15 pounds," The Bronx Zoo said in a statement.
They say an alligator of her size typically weighs between 30-35 pounds.
A disturbing discovery was also made after radiographs were taken of the gator, estimated to be between 5 and 6 years old. They showed that the alligator had ingested a bathtub stopper about 4 inches in width.
The zoo says the alligator is in too weakened a condition to attempt to remove the stopper and will provide care for her and see how she responds to treatment.
"The tragedy of this situation is a reminder that wild animals do not make good pets and that responsible pet ownership means making choices that will not negatively impact an individual animal or the environment," the zoo said.
City officials are still looking for the person responsible for dumping the alligator.
Releasing animals in New York City Parks is illegal. If you see an abandoned animal, the best thing to do is leave the animal where it is and call 311 or locate an Urban Park Ranger in the park.
Urban Park Rangers respond to around 500 reports of animal conditions per year citywide.
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