LAURA LUNDQUIST, Staff Writer
Although the wolf population in Yellowstone National Park is probably quite different now than it was at the end of 2012, the park’s 2012 year-end report still notes some valuable trends related to packs in the park.
In the recently released Wolf Project Annual Report 2012, biologists detailed how the population had declined 15 percent over the past three years and ended 2012 with at least 83 individual wolves.
That’s near the population size of the late 1990s after wolves were introduced in 1995.
Lead biologist Doug Smith said the population ballooned in the mid-2000s as all animal populations do after entering a new unexploited territory.
The northern range packs expanded quickly due to the over-abundance of elk but now have declined 60 percent since 2007. Packs in the interior of the park didn’t take off as much so they’ve lost just 23 percent of their peak population.
This reduction represents the phase after introduction where the population is finding a more long-term balance.
Five packs in the northern range account for more than a third of the park’s population, and the higher density meant higher rates of disease.
Mites that carry mange have been prevalent in the park since 2009, and seven packs, including the five northern-range packs, were infected in 2012.
Six other packs roam the rest of the park. Around two-thirds of the alpha females had pups in 2012.
Twelve wolves were shot by hunters outside the park, but Smith noted that wolves were also dying because they were competing with other wolves for the reduced numbers of elk in the park.
Seven wolves were confirmed as having been killed by other wolves.
Elk numbers have decreased over several years in the northern range due to a number of factors.
In addition to being hunted by humans, wolves and grizzly bears, elk have also been affected by climate-change factors such as changing spring green-up periods and increased parasite loads.
Still, elk appeared to account for almost two-thirds of the wolves’ diets. Biologists were able to confirm 159 elk kills, almost a third of them calves.
But that’s down from the 267 elk killed in 2011 and 211 killed in 2010.
The report notes that the reduction in elk populations has caused wolves to seek out bison more as a food source. The increasing number of bison available has also contributed as the park population has climbed past 4,000.
Finally, the winter of 2012 was mild so elk were less vulnerable to attack. Also, bison calve earlier than elk so wolves tended to target their young.
The park packs hadn’t hunted bison much before so Smith said the trend could be important.
While wolf packs shrank, the number of people traveling to the park to view wolves has climbed.
In 2012, park staff had more than 12,000 contacts with 27,500 people who observed wolves.
That was up from the 25,000 in 2011, however, it was nowhere near the 2008 peak of 35,000.
Fewer people are willing to make the trip if they can’t have a guaranteed sighting, and fewer wolves meant wolves were harder to find. Wolves were visible for 550 hours in 2012 compared to 830 in 2008.
The park produces the wolf report a year behind due to the time it takes to process the data.