Invasive Species

Burmese pythons can become enormous yet remain remarkably difficult to detect. A 2024 study by Miller et al. developed an environmental-DNA assay capable of distinguishing four invasive constrictors now reproducing in South Florida. The technology could strengthen early detection and monitoring—but a positive DNA sample tells us a snake was present, not how many snakes are there or whether a reproducing population exists.

Reticulated pythons are the world’s longest snakes, formidable predators, and occasionally predators of humans. Drawing on Headland and Greene’s remarkable 2011 *PNAS* study of Agta hunter-gatherers, this article explores human–python ecology, the pet trade, extreme body size, and what it means now that reticulated pythons are established and reproducing in Puerto Rico.

Reticulated pythons are no longer just occasional escapees in Puerto Rico. Evidence from wild adults and neonates, agency records, genetic research, and scientific publications now supports an established, reproducing population—but its size, range, spread rate, and ecological effects remain poorly understood.

How quickly could Burmese pythons spread beyond South Florida? Research on cane toads and invasive snakes shows why invasion fronts can accelerate—and why past rates of spread may not reliably predict the future.

A Burmese python sighting far from the Everglades does not prove range expansion. Because these snakes are extraordinarily difficult to detect, reproducing populations may exist for years before enough observations accumulate for us to recognize them as established.

Two models of the same invasive snake produced remarkably different maps. A closer look at the data and assumptions behind them shows why a precise-looking prediction is not necessarily a reliable one.

How far beyond South Florida could Burmese pythons eventually spread? Climate models can help answer that question, but their predictions depend on assumptions about native ranges, source populations, extreme weather, ecology, and even evolution.

A genomic study comparing 48 Florida Burmese pythons sampled before the 2010 freeze with 49 sampled afterward found rapid genetic change and evidence of natural selection. Michael E. Dorcas examines what changed—and why the freeze may have been only part of the evolutionary story.

In January 2010, one of South Florida’s most severe cold spells killed many Burmese pythons—but many survived. Michael E. Dorcas examines how behavior, refuge use, and inherited variation could allow a single extreme event to alter the evolutionary trajectory of an invasive population.

In 2009, ten Burmese pythons from Everglades National Park were placed in a semi-natural enclosure in South Carolina. Their responses to an unusually severe winter revealed surprising cold tolerance—and the critical importance of refuge use and behavior.