Researchers believe the abnormally shaped flippers are the result of inbreeding.
A toxic algae bloom is believed to be behind the overwhelming numbers of severely sickened marine mammals.
Similar to human moms, bottlenose dolphins use a kind of high-pitched baby talk with their little ones.
"This shows that the decades-long effort to restore the river as a healthy habitat is working," crowed New York City's parks department.
The Mirage's Secret Garden and Dolphin Habitat is temporarily closed while it investigates the dolphin deaths.
Three bottlenoses — Johnny, Rocky and Rambo — were rescued from a tiny pool where they had entertained tourists.
Dolphins also reach across groups to engage in incredibly complex social behavior only previously seen in humans, say scientists.
“Usually, dolphins get bored with my experiments. We were tapping into something that is part of the dolphins’ world.” marine biologist Jason Bruck said.
Videos and photos of animals wandering deserted city streets amid the COVID-19 pandemic are wildly popular on social media. But be wary when you see these images -- misinformation about the animals is also spreading.
Militaries, including the U.S. Navy, have been training dolphins and other animals for decades.