Yellowstone wolf population is hit hard this year. Reasons not certain-
Back in 2005 after years of major population growth tapering off to stability, the Yellowstone wolf population suddenly crashed when all but 20% of that year’s wolf pups died. While the cause was not determined for sure, most think it was due to canine distemper.
The next two years, however, saw a rebuilding of the wolf population with high wolf pup survival rates. 2008 began with what appeared would be more growth with reports of very high pup counts, e.g., 24 pups in the Leopold Pack.
The first signs of trouble came, however, from the Slough Creek Pack which had a number of pregnant female wolves, but only one pup was seen. As the summer wore on, many packs seemed to have lost all of their pups and most at least some. Currently only the Gibbon Pack has a large number of pups left — ten — and it is the largest wolf pack inside the Park with 25 or more members. Despite its size it is not commonly seen. Its territory is not close to the Park roads.