The disappearance of the favourite prey of Puma concolor cougar—the white-tailed deer is a major factor in the early decline of the eastern cougar. As contact with humans and livestock grew it was subsequently hunted to near extinction especially in eastern USA and Canada. Farmers perceive at it as a threat and will attempt to kill pumas through hunting or poisoning carcasses as pumas are known to return to kills.
As the habitat of P. c. cougar fragments due to the construction of railroads, highways and cities, the cougar is threatened from increasing inbreeding, with individual lions becoming very isolated. While attempting to find a home range, young cougars may roam widely in search of unoccupied territory. This is when cougars are most likely to conflict with humans.
Puma concolor cougar is considered as "Presumed Extinct" by the IUCN.