From the Jackson Hole News & Guide in Wyoming:
Wolves’ return to the Greater Yellowstone Ecosystem a quarter century ago has been the primary force suppressing local mountain lion populations, a new study has concluded.
That hypothesis was tested and confirmed using data amassed over the 16 years that the Teton Cougar Project tracked 147 cats on the east side of Jackson Hole. It was already known that lion numbers in this area fell by half during the study period, which coincided with wolves reoccupying the landscape. While the new canine competition was suggested as an explanation for the puma decline, until now the connection had never been confirmed with a vigorous analysis.