Sept 22, 2014, the National Park Service has published its annual report about the numbers and health of reintroduced wolves in Yellowstone National Park.
There were at least 95 wolves in 10 packs and one group (8 breeding pairs) living primarily in Yellowstone National Park during December 2013.
Pack size ranged from 2 to 18 and averaged 8.6 wolves. Nine of 10 packs, plus one lone female, had pups. At least 41 pups survived to the end of the year.
2013 Wolf Territories in Yellowstone
Yellowstone Wolf Populations from 1995 - 2012
Staff detected 269 kills probably made by wolves in 2013, including 193 elk, 16 bison, 13 mule deer, and a few other species. Elk kills were calves and yearlings (43%), followed by cows (33%) and bulls (14%). Some kills could not be identified to age or sex. Bison kills included nine calves, two yearlings, two cows, two bulls, and one adult of unknown sex.
Other research involving wolves during 2013 included population genetics, population regulation, disease, hunting behavior, spatial analyses of territory use, pack leadership, multi-carnivore-scavenger interactions, breeding behavior, dispersal, and observations of wolf, grizzly bear, and bison interactions in Pelican Valley.