New Leopard Frog Found in New York City

The unique species, discovered near the Statue of Liberty, is the first amphibian found in the region in 150 years

Introducing Rana kauffeldi, a newly recognized New York City resident. Photo: Feinberg et al., PLOS ONE

There’s a newly discovered vocalist in the Big Apple with a sound unlike any other in the city.

In 2008, Jeremy Feinberg, a graduate student at Rutgers University, was wading around in a wetland on Staten Island when he heard something strange. In a swampy patch less than 10 miles from the Statue of Liberty, he picked up on a peculiar chirp-chirp call that was distinct from the croaks of the known leopard frogs on the island. Investigating that song ultimately led Feinberg and his colleagues to a new species of leopard frog—the first amphibian discovered in New York since 1854, and the first found in the U.S. in three decades. They describe this unexpected find today in the journal PLOS ONE.

The frog’s discovery clears up some long-standing confusion among New York City’s herpetologists. For more than a century, reptile and amphibian experts have been stymied by conflicting descriptions of the city’s two native leopard frogs. Debate, discord and backlash often broke out about what constituted which species, and why so much variation seemed to exist among them. In 1936, local herpetologist Carl Kauffeld correctly proposed that the two species were actually three. But the constant background of bickering and strife meant that the idea was never accepted in the scientific literature.

To finally settle the matter, Feinberg and his colleagues set about netting leopard frogs in the New York area, as well as taking acoustic samples throughout the region. When they compared the frogs they caught to the two known species, they found that the chirpy frog had only slight physical differences. For instance, its vocal sacs were a bit larger, and the backs of its legs were darker. The researchers then sequenced part of the frogs’ mitochondrial genome and compared the data with genetic information from the other two species. The chirpy leopard frog, they found, is indeed genetically distinct from all others. 

You can hear the little guy's calls here: 

The new species’ call is unique enough that it can be used as a proxy for judging whether the frog is present in a particular patch of swamp or wetland. To come up with an estimated population range, the team took acoustic samples up and down the northeast coast. The frog’s calls could be heard along a 485-mile strip spanning seven states, from central Connecticut to northeastern North Carolina. This area—particularly New York City—is “one of the most developed, heavily settled and well-inventoried places on Earth,” the team notes. And yet this leopard frog has managed to largely escape notice for years, demonstrating that even the most densely inhabited parts of the world can harbor some wild surprises.

The team named the new species Rana kauffeldi after Kauffeld, the herpetologist who first recognized the frog’s standing as its own species but whose observation was decades ahead of his time.