The Python Hunters tackle the debate over how the Burmese pythons came to be established in the Everglades. National Geographic rides along with these expert hunters as they uncover the mystery behind how these creatures came to roam the land.

As a cold front hits the state of Florida, the frigid temperatures kill thousands of animals of all species. The Python Hunters head out braving alligators, venomous snakes and the relentless cold to determine how the weather has affected the population of Burmese pythons.

The Python Hunters perform a necropsy on a Burmese python killed by cold weather to see whether or not it was a healthy predator. Then, the hunters head to the edge of a sawgrass marsh to explore through knee-deep waters in search of pythons. National Geographic joins the team as they trek through mud and water hoping to find this magnificent snake.

It's a new season of hunting, and the guys are back in the Everglades to see if a bitter winter has put a dent in the Burmese python population. From Green iguanas and Nile monitors, to rock pythons and the biggest nasty of them all - the 12-foot Burmese python - alien invaders have infested the Florida Everglades. And now an elite squad of hunters is fighting back. Patrolling one of the most beautiful and delicate environments on the planet, the Python Hunters are determined to get these invasive species under control. It's a high-stakes, adrenaline pumping conservation mission, and if they fail, one of the most important eco-systems in America may never recover.

The team is branching out, and starts hunting the elusive Nile monitor lizard. Their first stop is an infested Cape Coral canal. It's a high-stakes, adrenaline pumping conservation mission, and if they fail, one of the most important eco-systems in America may never recover.

The guys head to Louisiana to conduct some research on invasive reptile species, many of which escaped there in the wake of Hurricane Katrina. From Green iguanas and Nile monitors, to rock pythons and the biggest nasty of them all - the 12-foot Burmese python - alien invaders have infested the Florida Everglades. And now an elite squad of hunters is fighting back.