Burmese pythons help mice invade Florida

Invasive Burmese pythons kill many of the rats' natural predators, allowing them to multiply and invade the Everglades.

Burmese python and cotton rat. Photo: Rhona Wise/Danita Delimont — Burmese python and cotton rat. Photo: *Rhona Wise/Danita Delimont*

Burmese pythons are helping rats dominate parts of the Florida Everglades by wiping out many of their traditional predators, according to a study published in the journal Mammalogy. The surge in rats could disrupt an already fragile ecosystem and increase the risk of disease transmission to humans, Live Science reported on June 5.

The Burmese python ( Python bivittatus ) was discovered in Everglades National Park in 1979. Its population skyrocketed in the 1980s and 1990s. Today, tens of thousands of pythons live in the Everglades. Over the past 40 years, they have decimated many native animal populations, including bobcats, rabbits, and foxes.

However, small mammals did not appear to be affected by the presence of Burmese pythons, including cotton rats ( Sigmodon hispidus ). To investigate the impact of Burmese pythons on these species, the researchers caught 115 rats and fitted them with transmitters, 34 in areas with few pythons and 81 in areas with many pythons. They monitored the rats every two days and videotaped the predators involved when any rats died. In cases where rats were likely swallowed, the team analyzed rat DNA in their feces and regurgitated carcasses.

The team’s findings showed similar mortality rates in both areas. Although the pythons killed six tagged cotton rats, they did not significantly impact the overall rat population. But because pythons severely impact populations of large mammals like bobcats and foxes, this creates an ecological niche for rats to invade. As a result, in areas with high python populations, cotton rats are taking over communities, according to study author Robert A. McCleery, associate professor of wildlife ecology and conservation at the University of Florida.

The collapse of large and medium-sized mammal populations in the Everglades affects important ecological processes such as nutrient cycling and scavenging. Rats cannot replace the roles of missing mammals. Their dominance also has the potential to spread disease to humans. Cotton rats are reservoirs of viruses that can infect humans, such as Everglades virus (EVEV) and hantavirus.

An Khang (According to Live Science )

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