livescience.com Yahoo News 14 Oct 09;
In a new report, the U.S. Geological Survey (USGS) assessed the ecological risks that nine giant non-native snake species would bring if they were ever established in the United States. The result: Five of them pose a high risk and four pose a medium risk.
The nine species, including non-native boa, anaconda and python species, are invasive or potentially invasive in the United States. However, the authors write in their report that "at present, the only probable pathway by which these species would become established in the United States is the pet trade."
Among the high risk species are Burmese pythons, northern and southern African pythons, boa constrictors and yellow anacondas. These species put larger portions of the U.S. mainland at risk, constitute a greater ecological threat, or are more common in trade and commerce. Medium-risk species, including the reticulated python, Deschauensee's anaconda, green anaconda and Beni anaconda, constitute lesser threats in these areas, but still are potentially serious threats.
Both Burmese pythons and boa constrictors have been documented as reproducing in the wild in South Florida, with population estimates for Burmese pythons in the tens of thousands, although there has been some debate about whether or not the pythons will migrate out of this habitat.
The high risk snakes "mature early, produce large numbers of offspring, travel long distances, and have broad diets that allow them to eat most native birds and mammals," which increases their risk to ecosystems, the authors wrote.
In addition most of these snakes can inhabit a variety of habitats and are quite tolerant of urban or suburban areas, they said. Boa constrictors and northern African pythons, for example, already live wild in the Miami metropolitan area.
The authors also note that native U.S. birds, mammals, and reptiles in areas of potential invasion have never had to deal with huge predatory snakes before - individuals of the largest three species reach lengths of more than 20 feet and upwards of 200 pounds.
USGS researchers used available science data to forecast areas of the country most at risk of invasion by these giant snakes. Based on climate alone, many of the species would be limited to the warmest areas of the United States, including parts of Florida, extreme south Texas, Hawaii, and America's tropical islands, such as Puerto Rico, Guam, and other Pacific islands. For a few species, however, larger areas of the continental United States appear to exhibit suitable climatic conditions. For example, much of the southern U.S. climatic conditions are similar to those experienced by the Burmese python in its native range. However, many factors other than climate alone can influence whether a species can establish a population in a particular location, the report says.
Individuals of some species may also pose a small risk to people, although most snakes would not be large enough to consider a person as suitable prey. Mature individuals of the largest species - Burmese, reticulated, and northern and southern African pythons -have been documented as attacking and killing people in the wild in their native range, though such unprovoked attacks appear to be quite rare. The snake most associated with unprovoked human fatalities in the wild is the reticulated python. The situation with human risk is similar to that experienced with alligators: attacks in the wild are improbable but possible.
The report also notes that there are no control tools yet that seem adequate for eradicating an established population of giant snakes once they have spread over a large area. Making the task of eradication more difficult is that in the wild these snakes are extremely hard to find since their camouflaged coloration enables them to blend in well with their surroundings.
"This report clearly reveals that these giant snakes threaten to destabilize some of our most precious ecosystems and parks, primarily through predation on vulnerable native species," Dr. Robert Reed, a coauthor of the report and a USGS invasive species scientist, said in a statement.
The Fish and Wildlife Service and the National Park Service will use the 300-page report to assist in further development of management actions concerning the snakes when and where these species appear in the wild. In addition, the risk assessment will provide current, science-based information for management authorities to evaluate prospective regulations that might prevent further colonization of the U.S. by these snakes.
Report: 5 foreign snake species threaten US
Tamara Lush, Associated Press Yahoo News 13 Oct 09;
MIAMI – Watch out, animals of South Florida: It's a wild world out there. There are five species of foreign snakes just waiting to eat you.
More troublingly, according to a U.S. Geological Survey report released Tuesday, nonnative snakes like the Burmese python could slither their way north from the warm, humid conditions of South Florida.
The big snakes threaten native species and ecosystems because they mature and reproduce quickly, travel long distances and can eat almost anything in fur, feathers or scales, experts say.
The 302-page report could be a step toward a ban on importing constrictor-like snakes into the U.S., said Ken Warren, spokesman for the U.S. Fish and Wildlife Service's South Florida office. The FWC will now evaluate the report and seek public comment before recommending such a ban.
"In many aspects, the report confirms what we already knew: that these snakes are a problem and that they do pose some risk," Warren said.
The report analyzed nine kinds of snakes. Five — Burmese pythons, northern and southern African pythons, boa constrictors and yellow anacondas — are of "high risk" to the ecosystems of the U.S., especially in Florida.
Four others — the reticulated python, Deschauensee's anaconda, green anaconda and Beni anaconda — are considered medium risk to ecosystems.
Scientists are already studying where Burmese pythons can survive in the U.S. Seven are being studied in a natural enclosure in South Carolina to see if the tropical natives can live through colder winters.
The number of invasive pythons in South Florida and throughout Everglades National Park has exploded in the past decade to potentially tens of thousands, though wildlife officials aren't sure exactly how many are out there.
Scientists believe pet owners have freed their snakes into the wild once they became too big to keep. They also think some Burmese pythons may have escaped in 1992 from pet shops battered by Hurricane Andrew and have been reproducing ever since.
Officials say the constrictors can produce up to 100 eggs at a time. Dr. Robert Reed, a research biologist with the U.S. geological survey, said everything from small wood storks, alligators and bobcats have been found in the stomachs of dead pythons.
Reed said the native animals of Florida aren't used to living near super-predatory snakes, and in time, entire wildlife populations could be wiped out.
"The fear is that something will happen akin to the situation with brown tree snakes on Guam," said Reed. "There, within 40 years of arrival, the snakes wiped out 10 of 12 bird species on island."
Reed was quick to point out that these free-range snakes pose a "minuscule" threat to people.
"All of the known fatalities involving giant snakes are from pet snakes, and usually to the owners," he said.
In July, an 8-foot pet python strangled a toddler in Central Florida.
Officials have tried to crack down on the invasive species; this summer, the Florida Fish and Wildlife Conservation Commission announced that the state would allow a few permitted snake experts to begin hunting, trapping and killing the nonnative pythons in an effort to eradicate them. Hunting the snakes is not allowed in Everglades National Park.
Between Jan. 1 and Oct. 5, some 270 Burmese pythons have been removed from the park.
"It's just very difficult to eradicate them," said Linda Friar, a park spokeswoman. "The snakes are very difficult to locate."
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U.S. Geological Survey report: http://www.fort.usgs.gov/Products/Publications/pub(underscore)abstract.asp?PubID22691
Alien Giant Snakes Threaten to Invade Up to 1/3 of U.S.
Ker Than, National Geographic News 14 Oct 09;
Nine species of giant snakes—none of them native to North America and all popular pets among reptile lovers—could wreak havoc on U.S. ecosystems if the snakes become established in the wild, according to a new study by the U.S. Geological Survey (USGS).
Two of the giant snakes are already at home in Florida. One of them, the Burmese python, has the potential to infiltrate the entire lower third of the U.S., the study says.
Mature individuals of the largest of the nine giant snake species—the Burmese, reticulated, and northern and southern African pythons—have been known to attack and kill people. But attacks on humans are rare, and scientists think the snakes pose minimal risks to humans.
Some of the snakes can grow longer than 20 feet (6 meters) and weigh more than 200 pounds (90 kilograms).
All nine giant snakes are considered invasive or potentially invasive, meaning they could live and reproduce in parts of the U.S. The snakes mature rapidly, produce large numbers of offspring, are not picky eaters, and can survive in a variety of environments.
The report names five giant snake species as high risk, saying they "put larger portions of the U.S. mainland at risk, constitute a greater ecological threat, or are more common in trade and commerce": the Burmese python, northern and southern African pythons, boa constrictor, and yellow anaconda.
The other four species—the reticulated python, Deschauensee's anaconda, the green anaconda, and the Beni anaconda—are considered medium risk.
Thousands of Giant Snakes Already in U.S.?
The giant snakes are native to a variety of countries in Africa, South America, and Asia.
For the study, USGS scientists examined the potential for each of the nine species to thrive in regions of the U.S. that match the reptiles' native habitats.
Two of the species—the Burmese python and the boa constrictor—have been confirmed to be breeding in parts of Florida. The other seven species are not as established but are considered potential threats.
While the possible ranges for some of the giant snakes are limited to parts of Florida and Texas, other species could spread more widely. The Burmese python, for example, could spread across the lower third of the country, the study concludes.
Scientists estimate that there could be tens of thousands or even hundreds of thousands of these giant snakes already living wild in the United States. However, due to the snakes' camouflage, humans rarely notice them.
"For every snake that you see," said study co-author and USGS biologist Bob Reed, "there could be a thousand snakes that you didn't see."
Giant Snakes Spell Death Sentence?
Most of the giant snakes found in the wild were once pets that either escaped or were released by humans after they had proved too difficult to care for, the report says.
While humans may think they are doing their pets a favor by releasing them, freedom for the snakes could be a death sentence for many North American ecosystems.
"If you want to be good to Mother Nature, do not under any circumstances let [your snake] go," said study co-author and USGS zoologist Gordon Rodda. "You'd be better off euthanizing it than releasing it."
And though some of the species occasionally attack humans, Rodda added, "the main damage that we see from these snakes is ecological."
For example, the post-World War II invasion of brown tree snakes on the U.S. territory of Guam has decimated the South Pacific island's native wildlife populations.
Many of the mammals, birds, and lizards that the tree snake—a native of Australia, Papua New Guinea, and the Solomon Islands—preys on pollinate the island's trees and flowers, so Guam's native plants are also on the decline.
A similar loss of species diversity is possible in parts of North America, where many small animals are unaccustomed to the hunting styles of huge predatory snakes, the scientists warn.
"Our native animals don't have an evolutionary history with giant sit-and-wait snakes," Reed said.
Freeing Giant Snakes: Antisocial Act
The authors of the new study "didn't leave anything unturned," said Ken Krysko, a senior herpetologist at the Florida Museum of Natural History in Gainesville, who was not involved in the study.
"No one can dispute anything they wrote down in there."
The new study will be reviewed by the U.S. Fish and Wildlife Service (FWS) and National Park Service. The findings will be taken into consideration when determining options for controlling the snakes' spread, said FWS spokesperson Ken Warren.
One possible action, Warren said, is to declare the snakes as injurious to humans and the environment. This would prohibit importing the snakes into the United States and transporting them across state lines.
However, such an action would not make it illegal to own or sell the snakes.
It will also be important to educate the public on the ecological dangers posed by freeing giant snakes, said USGS's Rodda.
"It has to be understood as an antisocial act," Rodda said. "Just as friends don't let their friends drive drunk, friends don't let their friends release giant snakes."
