Fires in Brazil's wetlands killed almost 17 million animals in 2020

Ferocious fires across Brazil’s tropical wetlands last year are estimated to have killed almost 17 million animals, with small snakes and rodents thought to be the hardest hit.

Amid a year of historic drought across South America, blazes burned at least a fifth of western Brazil’s Pantanal, a region that includes the largest tropical wetland in the world. The fires are considered the worst in the region’s history.

This ecosystem is a biodiversity hotspot home to many animals, including hyacinth macaws (Anodorhynchus hyacinthinus), jaguars (Panthera onca) and capybaras (Hydrochoerus hydrochaeris).

To estimate how many vertebrates perished, Walfrido Tomas at research institute Embrapa Pantanal in Brazil and his colleagues undertook field surveys in burned areas to see which dead animals were found up to 48 hours after fires. 

They counted 302 carcasses across the surveyed areas. Most were small snakes, birds and rodents, but they also found a tortoise, an anaconda, armadillos and several primates. While they didn’t find any jaguars, some of the big cats were reported to have been killed by the fires.

Extrapolating their findings with data on species populations in the Pantanal, they concluded that a total of 16.9 million animals were killed by the blazes. Tomas and his colleagues say the figure is probably an underestimate because many vertebrates will have died of injuries later, and some may have starved in the aftermath or may be out of sight underground.

Alexander Lees at Manchester Metropolitan University in the UK says the severity of the fires means they will have had a “major impact” on the wetlands’ biodiversity. He says the research gives a notion of that cost to veterbrates, but the estimate comes with “considerable caveats” as it extrapolates from just 302 records and doesn’t account for how the fires would have differed across the Pantanal.

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