Red List assessment of the jaguar in Brazilian Amazonia Amazonia is the most important biome for the long-term survival of the jaguar in Bra-zil due to its relatively well preserved state and continuous area of adequate habitat. In the Brazilian portion of Amazonia the jaguar’s present extent of occurrence EOO continues to encompass the whole area of the biome, but the continued loss of habitat in the east and southeast limits of this biome, an area known as the “arch of de-forestation”, has resulted in a significant reduction and fragmentation of the jaguar’s area of occupancy AOO. Based on data from camera trap surveys we assumed an average density of 1-2 jaguars/100 km 2 for the majority of the biome, with the exception of well-preserved floodplain forest areas where the species is more abundant. Considering this average density, the effective population size to total population size ratio proposed by Frankham (1995, 2009), and the total remaining area of the biome, we estimated the present effective jaguar population size for Amazonia in Brazil to be < 10,000 individuals. In addition the jaguar population is likely to be decreasing in this biome as a result of habitat loss, direct persecution and depletion of prey population. In our evaluation the jaguar should be classified as Vulnerable C1.