Cougars, like Wolves and Bears will kill members of their own species...........Reasons for these intraspecific conflicts include "outsiders" intruding on home territories and to eliminate youngsters of another male(to bring resident female back into breeding readiness).........In the case of Cougars, infanticide has been documented as well as killing of older animals. In New Mexico, infanticide has been reported as high as 44% of all kittens, and 100% of juvenile deaths and 52% of adult deaths were caused by other cougars. It appears that adult males are most probably carrying out most of these intraspecific killings (Logan and Sweanor 2000)...... Similar findings of intraspecific killing were reported in a study of a density cougar population on Vancouver Island (Hahn 2001).............In Florida, where there are roughly 100 Cougars surviving, January through May of this year has already recorded 17 fatalities--3 deaths specifically from intraspecific fighting

Panther found dead, killed by another panther in fight

 The Florida Fish and Wildlife Conservation Commission reported this afternoon that biologists found an endangered Florida panther dead in Bird Rookery Swamp in northern Collier County.

The male panther, estimated to be about 1 year old, was killed in a fight with another panther, biologists reported.
The carcass was found about a mile west of the stretch of Immokalee Road that turns north toward Corkscrew Swamp Sanctuary.
So far this year, 17 panthers have been found dead, six of them in collisions with vehicles and three in fights with other panthers.
Another four panther kittens were killed in the wildfire that swept through Big Cypress National Preserve in May, and one cuase of death is listed as unknown. Three deaths are still under investigation.