Pythons Eat Everything. Now Scientists Think They're Targeting Everglades Wading Birds

WLRN Public Media | By Jenny Staletovich

Published April 12, 2019 at 5:35 PM EDT

Researchers with the Conservancy of Southwest Florida in Naples pull mating pythons from a burrow in 2016. Source: Conservancy of Southwest Florida

Burmese pythons, the voracious invader of the Everglades blamed for wiping out small mammals, may now be feasting another marsh resident: wading birds.

A new study published this week [APRIL 10] in the journal PLOS One by the University of Florida and U.S. Geological Survey examined DNA in water and found the snakes appear to be congregating around tree islands where wading birds nest. Researchers compared water at 15 nesting islands to water without nesting birds, and found higher amounts of snake DNA near nesting islands.

A second study also showed birds may increasingly be targeted by snakes. In that study, researchers used trail cameras to photograph snakes eating eggs and young birds at a rate five times greater than raccoons, rat snakes and other native predators. That study was published earlier this month in the journal Biological Invasions.

“We already knew that pythons are responsible for eating over 90 percent of the mid-sized mammals in the Everglades," said co-author Peter Frederick. But "this is the first time we have documented pythons foraging on nestlings within densely packed colonies."

In the vast Everglades, tree islands draw herons, egrets, storks and other wading birds during nesting season, sometimes in vast colonies. While the number of islands has dwindled over the years because of flood control, the islands still provide much of the habitat the birds need during the season.

Researchers have long suspected the concentration of birds was also likely attracting the snakes. But collecting evidence in the harsh landscape, or tracking the perfectly camouflaged snakes, was daunting.

DNA in water is a relatively new line of attack but has helped improve python research. A study last year found Burmese pythons could be crossbreeding with Indian pythons to produce a kind of super snake. Another study found Florida's pythons may be evolving to be more tolerant of cold than their Asian cousins.

Given their huge appetite - pythons can eat more than their own body weight and grow up to seven feet long in their first year - researchers worry the snakes now may start wiping out bird populations.

“They aren’t evolutionarily prepared to deal with this kind of predator," Frederick said.