Yellowstone Wolf Project biennial report, 1995 and 1996

Phillips, Michael; Smith, Douglas

After 20 years of planning and study, wolves were reintroduced into the greater Yellowstone ecosystem. Fourteen wolves in 1995 and 17 wolves in 1996 were captured in Canada, translocated to Yellowstone, placed in acclimation pens for ten weeks (three pens in 1995 and four pens in 1996), and then “soft” released into the wild. After release, and an exploratory period, all but one released wolf pack settled in the vicinity of their acclimation pens. Wolves unexpectedly bred in the acclimation pens both years, with two litters born in 1995 and two in 1996 (although one of the females that bred in the pen died before giving birth shortly after release in 1996). Three litters were bred and born in the wild in 1996, so population growth exceeded the expectations of the Environmental Impact Statement (EIS). At the end of 1995, there were 21 wolves in three packs, and at the end of 1996, 51 wolves in nine packs. The wolves fed primarily on elk, although moose, deer, a pronghorn antelope, and a mountain goat were also preyed upon. No bison were killed, although wolves tested them on several occasions. Wolf kill rates were generally high, with an elk killed on average by a pack of wolves about every 1.1 to 5.0 days. Wolf depredation on livestock was less than what was predicted in the EIS. Some released wolves were recaptured and placed into captivity for management reasons. Two wolves died during 1995 and nine during 1996. Human activity, including motor vehicle accidents and legal and illegal killing, was the primary cause of mortality.

Yellowstone Wolf Project biennial report, 1995 and 1996

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