Burmese pythons blamed for mammals' decline
A Burmese Python in captivity
A study in the Florida Everglades National Park has blamed the dramatic rise in numbers of Burmese Pythons – believed to have first been introduced to the Everglades in the form of abandoned pets – for the equally dramatic drop in numbers of mammals in the park. Sightings of rabbits, opossums, white-tailed deer, bobcats and raccoons have all dropped in areas where pythons are known to be prevalent. Coyote sightings slightly rose when compared to earlier studies, but overall sightings remain low. No rabbits or foxes were found at all in the most recent survey, and opossum sightings had dropped by 99%.
The Everglades National Park covers approximately 25% of the Florida Everglades, which were swampland gradually drained and reclaimed for human use over the previous century. Pythons were first recognised as being established in the Park in 2000, but intermittent sightings were recorded over twenty years prior to that date. It has now become apparent that the pythons are firmly established across a region of thousands of square kilometres, although no reliable figures as to their total numbers are available due to the impracticalities of searching large areas of swampland.
"You are only seeing a small fraction of the numbers that are actually out there," said Professor Michael Dorcas from Davidson College in North Carolina, one of the study's authors. "They are a new top predator in Everglades National Park - one that shouldn't be there. We have documented pythons eating alligators, we have also documented alligators eating pythons. It depends on who is biggest during the encounter." he added.
Secretary of the Interior Ken Salazar announced earlier this month that the US Government was shortly to approve a ban on importing Burmese pythons. However, the proposed ban has already drawn criticism from observers, who argue that it is too late for such a ban to have any meaningful effect.
Professor Dorcas has proposed that more research should be undertaken to assess the impact of such large declines in the local mammal population. "It's not unreasonable to assume that any time we have major declines in mammals like this it's going to have overall impacts on the ecosystem. Exactly what those are going to be, we don't know. But it's possible they could be fairly profound." he said.
The BSAVA has opened submissions for the BSAVA Clinical Research Abstracts 2026.
