A population of exotic invasive Cuban treefrogs has been discovered in New Orleans, more than 430 miles (700 kilometers) from the nearest known population in Florida, making this the first known breeding population in the mainland United States outside that state, reports a new study by the U.S. Geological Survey.
Scroll down to hear and download calls of Cuban treefrogs and two native treefrogs.
Cuban treefrogs can drive out native frogs and be a nuisance to homeowners. Native to Cuba, the Bahamas, and the Cayman Islands, Cuban treefrogs have successfully bred in Florida since at least 1951. Established populations of the treefrog species have also been found on Puerto Rico and the U.S. Virgin Islands.
“Homeowners may be familiar with the nuisance species as they have noxious skin secretions, lay their eggs in bird baths and fish ponds, and they can clog plumbing and cause power outages by short-circuiting utility switches where they seek refuge,” said USGS Research Ecologist Brad Glorioso, the lead author of the study. “Cuban treefrogs grow much larger than native treefrogs, have been known to displace native treefrogs, and will even eat smaller frogs, often of their own species. A decline in native treefrogs could have consequences, since frogs act as both predator and prey in food webs.”
The invasive species may have hitched a ride on palm trees imported from Lake Placid, Florida, and planted in the Elephant Exhibit at the Audubon Zoo in March 2016. Elephant keepers noted the presence of unusual treefrogs soon thereafter.
According to Glorioso, the tight spaces at the base of palm tree fronds provide an ideal hiding spot for the treefrogs as they are inadvertently transported to distant places. Palm trees are frequently imported from Florida in large numbers to recently disturbed areas, including New Orleans following Hurricane Katrina in 2005.
“They often end up in places with unsuitable climates, but in south Louisiana, Cuban treefrogs appear capable of withstanding seasonal cold spells by seeking appropriate refuge,” said Glorioso.
In late 2016, reports of at least eight Cuban treefrogs of varying sizes on the grounds of the Audubon Zoo in New Orleans gave concern that a population may be establishing. Following additional reports in 2017 of suspected Cuban treefrog tadpoles and recently metamorphosed juveniles in Riverview, a part of Audubon Park between Audubon Zoo and the Mississippi River, the USGS began investigating the likelihood of an established population.
Between mid-September and mid-November of 2017, USGS scientists captured 367 Cuban treefrogs in just four surveys. In addition, in late October, approximately 2,000 Cuban treefrog tadpoles were removed from two pools of water in Riverview. The pooled water was then drained to eliminate any possibility of survival of overlooked tadpoles.
It is not yet known how the Cuban treefrogs have impacted Louisiana’s native treefrogs, but USGS scientists did note a lack of native species during their surveys. No native treefrogs were captured at Riverview, where the highest density of Cuban treefrogs were found.
Cuban treefrogs are not a harmless invasive species, says Glorioso, and eradicating the recently discovered population in Louisiana is improbable.
“Right now, the hope is that the Cuban treefrogs do not reach and become established in the large tracts of public land, including the Barataria Preserve of Jean Lafitte National Historical Park and Preserve, just across the Mississippi River,” said Glorioso.
The study has been published in Biological Invasions, and can be accessed online at https://rdcu.be/Meqv .