Python problem grows in the Everglades
National Geographic is watching South Florida with a growing sense of unease over the alien monsters eating any creature who wanders into the Everglades:
…[T]his is “the first study to show that pythons are having impacts on prey populations—and unfortunately those impacts appear to be pretty dramatic,” said study leader Michael Dorcas, a herpetologist at Davidson College in North Carolina.
“We started the study after we realized, Man, we’re not seeing a lot of these animals around anymore,” Dorcas said.
But “when we did the calculations, we were pretty astonished.”
For the study, Dorcas and colleagues conducted nighttime surveys of live and dead animals on roads between 2003 and 2011. Such numbers provide estimates of how many animals of a certain species are present in a given area.
The scientists compared these data with similar surveys conducted in 1996 and 1997.
Before 2000 it was common to see mammals such as rabbits, red foxes, gray foxes, Virginia opossums, raccoons, and white-tailed deer on roadways after dark, the team says.
But the 2003 to 2011 surveys—which covered a total of nearly 35,400 miles (57,000) kilometers of road—revealed “severe declines” in mammal sightings, according to the study, published this week in the journal Proceedings of the National Academy of Sciences.
Raccoon observations dropped by 99.3 percent, opossum by 98.9 percent, and bobcat by 87.5 percent. The scientists saw no rabbits or foxes at all during their surveys.
Though sampling roadkill seems like a really clever idea, I do think there’s a problem with their methodology. During the recession, people have been driving around a lot less, especially over the bits of highway that lie between coasts (not so many weekend trips to Naples or Miami Beach). Not so much fewer animals as fewer cars. I wonder if they compensated for that.