Share this article
Wildlife Featured in this article
- Burmese python
- American redstart
- Sora
- Muscovy duck
TWS2024: Burmese pythons eat their way across the continent
Fecal samples reveal that the invasive snakes’ ecological footprint extends past southern Florida
Voracious Burmese pythons in southern Florida truly have a taste for international food. Fecal analysis showed the snakes are eating birds that have traveled as far away as Canada before meeting their fateful end in the Everglades.
“Burmese pythons are generalist predators—they eat everything and anything they come across,” said TWS member Kate Davis, a biology student at the University of Florida.
Invasive Burmese pythons (Python molarus bivittatus) have spread rapidly through parts of southern Florida where the temperature is suitable. In this area, they eat a wide variety of prey, from birds to small mammals, bobcats (Lynx rufus) and even small alligators (Alligator mississippiensis).
When they eat, the snakes are efficient at digesting—Davis has seen cases where they have swallowed entire deer and only single hooves or teeth passed through their guts.
A feathered passport stamp
But feathers often pass through their systems relatively intact. Because of this, Davis saw an opportunity to use isotope analysis on feathers left behind in Burmese python feces. Isotopes in carbon, nitrogen and other elements leave a signature that can reveal information about birds, like where they fed in recent weeks. “It acts like a passport stamp,” Davis said.
Davis and her colleagues wanted to use this information to find out whether the species that the pythons were eating were local, or if their prey came from farther afield. But she wasn’t sure whether the isotopes would be degraded during digestion or partial digestion.

As a proof of concept, she took Muscovy ducks (Cairina moschata), another nonnative species that has spread across southern Florida, to Steve Tillis, a scientist with Archer Reptile Center who kept captive pythons in the state. Davis and her colleagues examined the hydrogen isotopes of the ducks, then fed them to the snakes, then tested the isotopes again to see whether they changed during digestion.
The tests revealed they didn’t change, Davis stated during a presentation at the 2024 TWS Conference in Baltimore, Maryland.
What birds are on the Menu?
Armed with this knowledge, Davis collected feathers from several species and took them to the Smithsonian Institution’s Feather Identification Lab.
Ongoing analysis there has identified 58 different bird species remains that came from the digestive tracts of Burmese pythons. While most of these were Florida birds, Davis was surprised to find 14 different species of nonpermanent residents. These included some closer neighbors that are residents of northern Florida, as well as birds from much farther north. Two individuals, one sora (Porzana Carolina) and one American redstart (Setophaga ruticilla), came all the way from Canada. The redstart flew over 2,090 kilometers before meeting its ignoble end.
Davis said this study shows that while wildlife managers think of Burmese pythons as a southern Florida problem, it’s really much larger due to the importance of the area for bird migration. “Florida is such an important crossover flyway,” she said.
As a result, she hopes that more agencies—national and international—can collaborate on dealing with Burmese pythons.
“It’s the first study that shows that this problem goes beyond state borders and even national borders,” Davis said. “Animals don’t care about the borders that we created.”
Header Image: Kate Davis inspects fecal samples at the Smithsonian Institution’s Feather Identification Lab. Credit: The Smithsonian Institution Feather Identification Lab