We conducted ground surveys along line transects to estimate the first-order impact of the 2020 wildfires on vertebrates in the Pantanal wetlands, Brazil. We adopted the distance sampling technique (Burnham et al 1980) to estimate the densities and the number of dead vertebrates in the 39,030 square kilometers affected by fire. We covered 123 transects scattered in the floodplain, up to 72 hours after the fires, mostly within 24 or 48 hours. We recorded the perpendicular distance between each carcass found in the field and the line transect. The carcasses were identified at least at Order level, down to species level when possible. The surveys were conducted from August to November 2020.