Yellowstone Wolf Project Annual Report
August 29, 2017
There were at least 108 wolves in 11 packs (7 breeding pairs) living primarily in Yellowstone National Park (YNP) through December 2016 (figures 1& 2). Breeding pairs are defined as an adult male and an adult female with two pups that survive through the end of the year. Overall, wolf numbers have fluctuated between 83-108 wolves and 6-9 breeding pairs from 2009 to 2016. Pack size in 2016 ranged from 3 to 18 (table 1), averaging 9.8 in size. Park-wide, 36 pups survived to year end, 16 in northern Yellowstone and 20 in the interior of the park, with an average of 4.0 pups per pack surviving for 9 packs with confirmed reproduction.