Large felids (>30 kg) have exclusively carnivorous diets and depend upon medium and large terrestrial prey to fuel high metabolic demands (Sunquist and Sunquist 2002, Carbone et al. 2007). Although some of them commonly use trees for resting, hunting, avoiding predators or competitors (e.g., leopards Panthera pardus ‐ Le Roux & Skinner, 1989 and pumas Puma concolor ‐ Santos et al. 2014), and others may prey on arboreal, aquatic and semi‐aquatic species (e.g., jaguars Panthera onca ‐ Azevedo & Verdade, 2012; and tigers Panthera tigris ‐ Mukherjee & Sen Sarkar, 2013), there are no documented cases of large felids living a primarily arboreal existence for extended periods. Here, we report the evolution of a unique lifestyle for a large terrestrial top predator, in which jaguars live an arboreal and semi‐aquatic existence for 3‐4 months of the year in a completely flooded environment during the annual high‐water season of the Amazon River Basin (Fig. 1).