Nearly half of the Pantanal’s jaguar population was directly affected by the fires that devastated the region in 2020, according to a study by Brazilian scientists. The impact may have been even greater in the Pantanal environmental reserves where Brazil’s largest carnivore lives.
The calculations are worrying because the Pantanal is one of the last great refuges of the species in the country, next to the Amazon – in other Brazilian ecosystems, populations of jaguars are rarely found. In addition to the deaths of big cats caused directly by fire, the destruction of areas that previously had ideal conditions for their survival can indirectly lead the animals to death or prevent them from finding mates to reproduce.
“In addition to evaluating the impact of fire on jaguars in the Pantanal in a comparative way over the years, the research also analyzes how this impact can be negative for the species if it occurs in an uncontrolled way, with high frequency and intensity”, he told the Sheet the first author of the research, Alan Eduardo de Barros, doctoral student at the Department of Ecology at the Institute of Biosciences at USP.
The work of Barros, who signs the study together with his advisor, Paulo Inácio Barros, and other researchers from Brazil, the USA and Paraguay, has just appeared in the scientific journal Communications Biology. The team combined satellite data on the 2020 Pantanal fires with information on the jaguar population in the region and on the movements of the animals across the territory.
These details come from studies done in the years before the fire disaster. As it is not possible to carry out a census, counting each individual of the species head by head, one of these works made estimates based on camera traps, devices that record the presence of an animal at certain points thanks to cameras with motion sensors. In addition to camera traps, this study also took into account the presence of vegetation cover considered adequate for jaguars, among other factors.
In fact, says Barros, “they slightly underestimate the population density in the Pantanal, for two reasons.” First, the previous study proposes that, at most, there would be 7 ounces per 100 kmtwo in the region. “But more recent research shows areas this size with almost 13 individuals,” he says. In addition, the work assumes that the cats would be more numerous in areas of dense forest, which is not true in the case of the more open Pantanal, but with an abundance of resources for jaguars.
Taking all this into account, it is estimated that there would be 1,668 individuals of the species in the Pantanal. Of these, 48 jaguars have been tracked over the years using GPS collars and their home ranges have been defined, that is, the territory they travel through frequently in search of food, shelter and partners.
The combination of all this information showed that the regions that would be the habitat of 45% of the Pantanal jaguars — or 746 individuals — were directly impacted by the 2020 fires. It is considerably more than the total area of the Pantanal that was affected then ( about a third). This is three times greater damage than the average for areas affected by fires in the ecosystem in the previous 15 years.
Worse still, of the 48 jaguars monitored by GPS, 38 had their home ranges, which should be their main refuges, directly affected by the burning of vegetation and soil. And more than half of the reserves under environmental protection that are part of these living areas also suffered the effects of fires.
There are still no indications that the monitored jaguars have died, although this was the fate of two animals of the species that were rescued with burns in 2020. It is very likely that this is just the tip of the iceberg. A recent estimate suggests that 17 million vertebrates may have died in that year’s disaster.
“I believe that the greatest impact of fire on the jaguar population was the need to look for new areas with more resources”, explains the USP researcher.
She explains that jaguars are not always totally solitary hunters. When there is an abundance of food — this is the case in the Pantanal normally, when it is not burning — there is some overlap of territories between adult animals. The region is where the largest individuals of the species are found.
However, if fires like these recur frequently, the situation can get very ugly.
“The fight for green areas, for the proximity of water and for females, as well as the animals’ own energy expenditure, can intensify very quickly”, he analyzes. “If the environment recovers, the population would tend to return to the equilibrium point, but otherwise, it could change, supporting a smaller number of individuals.”
Avoiding this type of imbalance is likely to get more complicated in the coming decades, as the human-induced climate crisis has increased the number of extreme weather events, including major droughts, that facilitate fires. The scale and locations of fires in the Pantanal in 2020, however, indicate that, for the most part, they were caused directly by humans, such as rural landowners in the region.