The Burmese Python is now firmly established in Florida. As of July, 2014 an estimated 150,000 of the animals lived wild in the state. In an effort to prevent similar problems in the future, the U.S. Fish and Wildlife Service (FWS) added four snakes to a listing of “injurious wildlife species”.

The reticulated python, and three species of anaconda (green, Beni and DeSchauensee’s) can no longer be legally imported into the United States or its territories and snakes already in the country cannot cross state lines.

The decision was made following a public comment period and will take effect on April 10, 2015.

Speaking at an event to announce the rule at the Arthur R. Marshall Loxahatchee National Wildlife Refuge in Florida, FWS Director Dan Ashe said “large constrictor snakes are costing the American public millions of dollars in damage and placing at risk 41 federally and state-listed threatened or endangered species in Florida alone. Today’s action will help prevent humans from contributing to the spread of these snakes,” according to a statement.

The process began in March of 2010 when the FWS proposed listing nine species of large constrictor snakes that are not native to the United States. The northern and southern African pythons, Burmese pythons and yellow anaconda were officially listed in 2012 and public comment began on the remaining species in 2014. Of the nine originally proposed species only the boa constrictor was not listed.

“Although the boa constrictor can be damaging to U.S. wildlife, the circumstances surrounding the species, which include widespread private ownership and domestic breeding, render importation and interstate transport prohibitions less effective,” reasoned the FWS.

Small numbers of green anaconda and reticulated python, the largest snakes in the world, have already been found in the wild in Florida. Some are believed to have escaped, while others were released intentionally. According to the FWS, this puts native wildlife, not adapted to deal with the large predators, at risk.

The DeSchauensee’s and Beni anacondas are not currently known to be in the United States. Nevertheless, the FWS determined that listing the snakes now was the best way to prevent future problems.

Species are added to the injurious wildlife list to protect human safety as well as agriculture, forestry, horticulture and native wildlife species. Factors considered include the animals estimated ability to survive and spread in the wild, resource managers ability to control the species and their potential impact on threatened or endangered species.

According to the FWS rules, most current owners of these animals will not be affected. However new animals cannot be imported into the U.S. nor can breeders sell the snakes across state lines. The laws of the various states govern rules within state borders.

As temperatures warm due to climate change, wildlife officials are becoming more concerned about potential invasive species. Warmer temperatures may allow some plants and animals to survive and establish themselves in U.S. habitats that would not have survived previously.

In recent years, Burmese pythons have become firmly established throughout the Florida Everglades. Despite the removal of more than 2,000 animals by the National Park Service since 2002, the snakes have continued to thrive and their numbers have continued to grow.