Cougars are ambushing and killing wolves—and no one knows why

They hungry.

Seriously though some predators do sometimes preemptively kill rival species as part of resource competition.

Its likely habitat loss and ecological collapse means it's no longer big enough for the both of them. That could explain why it's in specific areas.

Cats are one of the few mammals that kill for sport aside from humans. I’m sure it’s something aside from that and we’re the root cause, but it’s something to think about.

To eat I would presume? They're pretty territorial too though

They're in a dark alliance with the killer whales!