The title, Winter Study, refers to an actual ongoing study of wolves and moose, a a 50 year predator/prey study. Go here to Isle Royale, the National Park where this story takes place and read about it.
Park Ranger Anna Pigeon is sent to Isle Royale in Lake Superior to learn about managing and understanding wolves, as her home base of Rocky Mountain National Park might soon have their own pack. The team is housed in the island’s bunkhouse along with two scientists from Homeland Security, who are assessing the study, thinking to end the 50 year study in order to open the park in winter so that the border with Canada can be watched. The whole anti-terrorist thing. Soon after Anna’s arrival, the 3 wolf packs begin to act strangely. Giant wolf prints are found, and Anna sees what she believes is an extra big wolf from the team's plane. The team comes to believe that perhaps a wolf/dog hybrid has been introduced to the island. Then one of the team members is savaged.
With all the mystery and action you could want, this is a great read right up to the end. I hated one part, which describes how one of the people was hurt and leaves you with NO sympathy for the bad guy. If you read this you'll see what I mean.