- August 30th, 2011
- in Yachting
A Frog You Don't Want to Kiss
“Our tiger was outside playing with a huge frog,” my boyfriend Richard said as he came through the door holding our new kitten Axl under his arm. A few minutes later when we sat down to dinner, Axl cried to be let out again.
“Go play with your new friend,” I said as I opened the door for him.
After a few more bites of palak paneer, we heard a chirping noise that Richard thought was a weird bird. The noise expanded into the loud, persistent cry that I associate with a cat indicating it has prey in its mouth. I went outside to find Axl beside the patio rain gutter batting at the frog but clearly in pain, so I picked him up and held him away from the amphibian, so it could escape. Instead of hopping away, the frog leapt towards us and landed on Axl’s stomach before I sort of flung it away. We brought Axl into the kitchen where he began foaming at the mouth and retching. Panicked, especially after my own experiences with consuming local toxins (manchioneel), I quickly looked up “cat poisoned by toad” on Google and learned that we should rinse his mouth out with water, wash off the gluey substance that was stuck to his whiskers, nose, paws and belly with soap and water, and give him some milk. We did, and he quickly recovered, but we were definitely freaked out. I hadn’t thought there were any toxic reptiles or amphibians in the BVI.
Friends told me that Axl’s encounter had been with a Cuban tree frog, and I soon discovered that these small amphibians are an invasive species in the BVI that secrete a toxic mucus when threatened. Scientist Clive Petrovic gave me some history about the frog, saying that they probably first arrived in the BVI in the 1980s at the JR O’Neal Botanical Gardens. This made sense, he said, based on his own experience owning a landscaping business when he would ship exotic plants all over the world. He noted, at the time, that diverse species, native and non-native, of “insects, snails, spiders, frogs” would hide in the plants, and if they didn’t escape, they’d be shipped to distant countries. “In most countries,” he said, “those containers are fumigated,” but that’s not the case in the BVI. A 2005 article in Herpetological Review agrees that most Cuban tree frogs are brought in on horticultural materials and cites Cane Garden Bay business owner Elvet Meyers as saying that the frogs were shipped in on pallets from Florida. In The Cuban Treefrog in Florida, Dr. Walter Meshaka reported an introduction to Necker Island “associated with nursery shipments from Florida.” Once they arrived in the BVI, the frogs traveled on vehicles—cars, heavy construction equipment, boats, barges—to other parts of the island and other islands, including smaller islands like Guana and Mosquito, but Jost Van Dyke has remained free of the invasive frog.
Recently, the USVI has been having a problem with animals being poisoned by cane toads—the invasive species that has been both intentionally and unintentionally introduced all over the planet. The July 26, 2011 cover story of the Virgin Islands Daily News featured an article about a foot-long cane toad poisoning a 100-lb dog, causing it to be “unconscious and paralyzed when it was found by its owner.” Luckily for us, the BVI does not have a cane toad population. Clive credited that to the fact that we don’t have the habitat for them to breed—freshwater pools or ponds. Cuban tree frogs, on the other hand, with their sticky frog feet, can climb and get into cisterns to breed. Cane toads can’t climb. So while we’re safe from cane toads, we still have cisterns full of Cuban tree frog tadpoles.
Once the tadpoles mature, they’ll eat “anything they can swallow,” according to Clive, but most of their diet consists of medium-sized insects. They are also known to eat vertebrates—frogs, anoles and geckos. The Herpetological Review article states, “interviews with BVI residents indicate a decline in native frog populations as the CTF [Cuban tree frog] increases in numbers.” To Clive, this makes sense “because they’re attracted to lights upon houses, and so are the coquis, geckos and anoles.”
Additionally, Cuban tree frogs don’t eat small insects, like mosquitos; instead, they eat the mosquitos’ predators. “As the population of Cuban tree frogs increases, so does the mosquito population because the small, whistling frogs eat mosquitos … but mosquitos are a bit too small for the Cuban tree frog, so they’d rather eat the little frogs.” Unfortunately, few things eat the Cuban tree frog. My kitten is evidence as to why. “I have had a number of reports and [have] seen photographs of the Virgin Islands boa catching and eating Cuban tree frogs,” Clive said, but during his own feeding trials on the snakes, he was not able to get them to eat the frogs, even after withholding food for a week.
Like mosquitos, the best way to control the population is to get them where they breed, so this means making sure the adult frogs cannot get into cisterns to lay their eggs. Spouts should be covered with screens to keep out the frogs (as well as mosquitos), and if a cistern is found to have tadpoles inside, Clive recommends draining it, finding out how they got in and correcting the problem, cleaning the cistern, and filling it back up. He said that he’s spoken with people who simply poured bleach in their cisterns to kill the tadpoles, but then you’re stuck drinking dead tadpole water. Yuck. Another way to prevent Cuban tree frogs from taking over is by fumigating containers and pallets that are shipped in from Florida or other zones known for invasive species.
I was relieved when Dr Walter Meshaka Jr, senior curator of Zoology and Botany at the State Museum of Pennsylvania and author of The Cuban Treefrog in Florida, informed me that the frog probably wasn’t attacking my cat, like I had assumed it was doing based on its behaviour; rather, it was more likely that it had accidentally jumped on Axl while “trying desperately to get away,” he said. “No Kamikaze tree frogs,” he added, “just ones whose escape directions get bollixed up.” Clive came to the same conclusion when I explained what I saw and suggested that my cat hopefully learned to avoid them, saying that “most animals only need one nasty encounter to develop such avoidance behavior.” I don’t know about Axl, but I have definitely learned from this experience.