Yellowstone's wolf population dropped by over a quarter last year, from 171 in 2007 to 124 in 2008. While wildlife officials say the decline isn't unusual, they are investigating for potential causes like disease or wolf-on-wolf killings.
"I anticipate over the long term that the numbers will go up and the numbers will go down," (Yellowstone chief of wildlife management Glenn) Plumb said.
Conservation groups are more concerned that the 27-percent population drop could spell eventual trouble for Yellowstone's wolves, which remain a marquee attraction and a popular symbol for America's national parks.
"Using Yellowstone as an example in terms of the number of wolves that have died from disease or from wolves killing other wolves, we're just very worried about management plans that will manage for the minimum, as natural causes can lead to population declines quite easily," said Melanie Stein, the Sierra Club's associate regional representative.
To see more controversy surrounding wolves—this time in Alaska—check out BACKPACKER's "Dogs of War."