Bob Reed: ‘Giant snakes are here now, doing ecological damage’

Bob Reed: In South Florida, the Burmese pythons have been found with everything from house wrens to white tailed deer in their stomachs.

Bob Reed is a wildlife biologist. He’s talking about one of several species of giant snakes, imported to Florida as exotic pets, that now threaten natural ecosystems here in the U.S. Reed is co-author of a 2009 USGS report assessing the potential risks of these snakes.

Bob Reed: Our report covered four species of python, four anacondas, and the boa constrictor. These include the four true giants, which are snakes that can reach or exceed six meters, or about 20 feet in total length.

Reed said Florida is a hub of importing and breeding for many exotic snake species, because warm temperatures allow reptiles to be bred in outside enclosures. He said that snakes might have escaped or been released into the wild, or it’s also possible that Hurricane Andrew, in 1992, freed many snakes.

Bob Reed: From an ecological standpoint, it really doesn’t matter how they got into natural habitats. The point is, they’re there now, and they’re reproducing, spreading, and they’re doing some ecological damage.

Reed said scientists are currently most concerned about South Florida ecosystems – such as the Everglades, where Burmese Pythons now threaten vulnerable native species. But because these snakes can tolerate different conditions, he said, they could eventually spread through the southern U.S. Reed told EarthSky that in the past 30 years, just under one million individuals of the species considered in the USGS report have been imported, with captive breeding multiplying that number. He told EarthSky that three of the nine snake species have established permanent populations in South Florida.

Bob Reed: As they expand, they’re likely to find habitats that are suitable.

He said the threat to humans is relatively small. Even though the snakes have been in the wild in Florida for over a decade, no human causalities have been reported there.

Bob Reed: We consider the primary risks to be ecological. For some native species, a population of predatory giant snakes could tip the balance against their survival.

Reed added that scientists are working on developing tools to control the snakes’ spread, and preventing other snake species from becoming invasive.He said that two pythons had apparently swum from the mainland to the island of Key Largo, where they were found to have eaten three endangered Key Largo wood rats. Only 200 of these species remain.

Bob Reed: When you’ve got two snakes that have eaten 1.5% of the population, and you know that you’re not catching all the snakes that are out there, that’s cause for concern. Especially when you talk about continued invasions from the mainland and the population potentially establishing on Key Largo. So you’ve got not only individuals coming over, but females breeding, and lots of babies coming out.

Reed gave the case of the brown tree snake as an example of the long term impacts on ecosystems.

Bob Reed: After World War II, the brown tree snake was accidentally introduced to Guam. Within about 40 years of its establishment, it had wiped out 9 of 11 bird species on the island, numerous lizards, and one of the bats. That caused a massive decline in pollinators, and a massive decline in the animals that disperse seeds. That’s changing the forest structure on Guam. So the overall ecosystem impacts go well beyond just the loss of the species that were consumed by the snakes. They have lots of downstream effects in terms of what’s going on with all the plants and animals on the island over time.

Reed said there is no “silver bullet” to controlling or eradicating snake populations once they are established.

December 14, 2009

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