Invasive albino kingsnakes are expanding throughout the Canary Islands, representing a huge threat to biodiversity, say experts who met this week to try to figure out how to stop the reptile.
With no natural predators, the kingsnakes—which are native to California—are growing bigger and badder, decimating local animal populations, including juvenile Gran Canaria giant lizards, which live only on the Canary Islands (map), a territory of Spain.
“Where the snakes are, most of the [young] lizards are missing,” said Robert Fisher, a U.S. Geological Survey (USGS) researcher who’s taking part in the discussions on the Canary Islands. (Read more about invasive species.)
With its offspring absent, Fisher now calls Gran Canaria giant lizards “the living dead”—a population doomed to extinction.
Albino kingsnakes originally came to the islands as pets about 10 to 15 years ago and either escaped or were set free by their owners.
But there is hope: The reptiles aren’t yet entrenched in the environment, Fisher said, and governments are actively trying to find a solution. “You often don’t get that level of commitment until it’s too late,” he said.
As the world warms, the spread of such invaders is becoming increasingly common. For instance, adaptable species—including many weeds and pests, as well as cold-sensitive, invasive species like the Burmese python in Florida—are expanding their ranges, said Peter Alpert, a program director in environmental biology at the U.S. National Science Foundation (NSF).
Here are some more invaders that have gripped other parts of the globe.
Brown Tree Snakes
Guam’s native species had no snake predators before these Southeast Asian and Australian snakes were inadvertently introduced to the Pacific island after World War II.
The reptiles have since eaten over half of Guam’s native species of birds and lizards and brought two-thirds of the bat species close to extinction, according to the USGS Institute for the Study of Invasive Species. (Related: “Drug-Filled Mice Airdropped Over Guam to Kill Snakes.”)
NSF’s Alpert calls it a “silencing of the forest.” To learn more about this altered ecosystem, NSF funds the Ecology of Bird Loss Project to study ways in which the absence of birds is affecting the rest of the ecosystem. For example, scientists want to know what happens to the plant life of the forest without the birds that once dispersed most of its seeds.
Cheatgrass came to the U.S. from Eurasia in packing materials in the mid to late 19th century. Its short life cycle and copious seed production make it able to spread quickly.
Sharon Gross, invasive species program manager for the USGS, said that cheatgrass and buffelgrass have altered ecosystems and fire dynamics in the American West.
“Cheatgrass is a very good fire fuel, and is often the first species to come back after a fire—in many cases preventing other native species from becoming reestablished,” she said.
This beauty is a beast. Native to the Indo-Pacific, lionfish were accidentally set loose in the Caribbean and waters off the southern U.S. in 1992 after Hurricane Andrew.
The fish have quickly become a problem for native animals: “It’s much bigger than the native reef fish and actively pushes them off the reefs,” Gross said. (Related pictures: “Sharks Taught to Hunt Alien Lionfish.”)
Plus, the fish have venomous dorsal fins and no known predators—besides, perhaps, humans. (See “Lionfish: Gotta Eat ‘Em to Beat ‘Em.”)
Four species of carp—bighead, grass, black, and silver—fall under the label of Asian carp, which were introduced into U.S. waters in the 1970s to control weeds and parasites, according to the U.S. National Park Service.
Some got into the Mississippi River, and they’ve been on the move since, muscling out native fish, lowering water quality, and injuring people by jumping out of the water (as seen in this video) when startled by boat noise. (Related: “Invasive Asian Carp Found Breeding in Surprising Location.”)
Gross said the USGS and other agencies have been trying to develop a chemical capsule coated with an enzyme that is only digested by, and is toxic to, the invasive silver carp. The method would target the carp without delivering fatal substances to other species.
Instead the toads became the pests, secreting poison through their skin, thwarting would-be predators, and spreading their population westward. (See “Australia’s ‘Road Warrior’ Toads Get Arthritis.”)
“That’s the one that comes up in the textbooks of why it’s not always a good idea to introduce a non-native to kill another non-native,” Gross said.
Tell us: How would you handle invasive species?