A recent study in the Florida Everglades shows that invasive Burmese pythons have become the dominant predator of the region, at least in some areas. Researchers from the U.S. Geological Survey and the University of Florida tagged and radio tracked marsh habits in a section of the everglades. Of the rabbits that died, almost 80 percent were consumed by pythons. A year after the study was complete, the study area showed no rabbit population at all.
This is the first empirical evidence that Burmese pythons are causing reductions in marsh rabbit populations. Researchers suspect that the snake is also responsible for the decline in other mid-sized animal populations.
Current estimates suggest that tens of thousands of Burmese pythons now populate the Everglades. Putting an accurate number on the population is difficult however. The animals are nocturnal, sleeping most of the day in carefully chosen hiding spots. Additionally, populations are generally counted by tagging animals that are found and re-releasing them and, in Florida, captured pythons are not returned to the wild.
While researchers have long believed that the pythons were preying on native animal populations. However, until now they haven’t had have hard evidence until now to show the pythons could cause severe population declines or local extinction, according to Robert McCleery, a University of Florida assistant professor in wildlife ecology and conservation who led the study.
In a 2012 study, researchers compared mammal populations from the 1990s, prior to the python population explosion, to similar wildlife surveys conducted between 2003 and 2011. That study showed that the python population was increasing and the local mammal population was declining. However correlation does not automatically mean causation and the previous study didn’t directly link the two population shifts.
“Previous studies implicated pythons in mammal declines in the Everglades, but those studies were largely correlative. This new study moves us from correlation to causation in terms of the impact of invasive pythons on native mammals,” said Bob Reed, a USGS research herpetologist and study co-author in a statement.
For the current study, researchers found 31 marsh rabbits living outside of the park. They moved them into selected areas inside the park. They also 15 rabbits in the Loxahatchee National Wildlife Refuge and 49 rabbits into 49 in Fakahatchee Strand State Park where there is no known python population to use as control groups. All of the rabbits were equipped with radio collars.
The researchers tracked the rabbits and found that 77 percent of the rabbits that died in the everglades were eaten by Burmese pythons. There is now no rabbit population at all in the Everglades test areas. In the control areas the rabbit population is large and thriving.
They also found that the warmer and wetter the weather, the faster the pythons ate the rabbits.
The study was published online in the journal Proceedings of the Royal Academy B.
To date all attempts to control or eradicate the population have failed, proving impractical or ineffective.
In 2013, the Florida Fish and Wildlife Conservation Commission held a month long “Python Challenge”, offering bounties for snakes. Because of the elusive, nocturnal nature of the animals the event resulted in only 68 captured pythons by 1,600 participants.
As of 2012 it is illegal to import Burmese pythons into the United States.
