Isle Royale (IR), Michigan is an island National Park located in the northwest corner of Lake Superior and 15 miles from the closest mainland near Thunder Bay, Ontario. The Park is open from April 16th to October 31st and is only accessible by boat during those months. It is the most remote National Park in the lower 48 and was established in 1940 and designated as wilderness under the Wilderness Act of 1964. Many people who spend time on IR, backpacking or paddling its 50+ inland lakes, seek a unique wilderness experience while enjoying the solitude of this remote island. The presence of wolves and moose on the island are a draw for many as they enhance the feeling of wildness. Wolves have inhabited this island since the 1940s and moose since the turn of the 19th century. As many as 2,500 moose and 52 wolves have lived on the island at one time.
Only two wolves and approximately 1,300 moose currently live on IR, and fearing that wolves will soon vanish from the island, National Park Service personnel have committed to augment the current wolf population in order to restore their predation on moose which maintains a balanced moose population. Without predation it is feared that moose will over-browse the island and permanently compromise the health of the ecosystem. For example, in the winter of 1995-1996, moose numbers were at a historic high and wolf numbers had remained low for almost a decade following the outbreak of disease. Moose, particularly on the west end of the island, had denuded the regenerating balsam fir, their primary winter forage. Following a particularly long winter, over 1,000 starving moose died. Use this link to read more about the proposed wolf reintroduction in the National Park Service ‘Draft Environmental Impact Statement’.
We were excited for our 4th winter field season working with the IR Wolf and Moose Project, started in 1958 to study the relationship between wolf and moose predator/prey dynamics and their effect on the island ecosystem. It is the longest running wildlife study in the world. Researchers, Rolf Peterson and John Vucetich from Michigan Tech University, study this system intensively each year during January and February. With pilots Don Murray and Don Glaser, they focus on counting moose in 91 study plots for
estimating moose population size, and locating wolves in order to estimate their numbers, record their activities and movement patterns, and find their kills for estimating kill rates.
As the ground crew, Lisa and I are responsible for collecting moose fecal pellets and urine by following fresh moose tracks in the snow and collecting balsam fir samples.
This year, moose pellets were analyzed in a process called microhistological analysis to determine diet composition of the moose. In this process, pellets are ground up, washed in solution, and then viewed through a microscope to identify the species of plant material in the diet. Results show that moose on IR feed predominantly on Balsam fir, Eastern white cedar, and numerous hardwood browse species. Chemical analysis of urine reveals how healthy a moose is by determining its urea nitrogen to creatinine ratio. A high ratio suggests a moose is food stressed and is metabolizing its own muscle for energy. The ratio of glucuronic acid to creatinine in urine tells us how much energy a moose is putting into detoxifying the plant material that it consumes. In their defense to moose herbivory, we are finding that previously browsed firs concentrate Plant Secondary Metabolites (defense toxins) into their new annual growth. The concentration of defensive toxins in fir samples help us understand why moose choose certain trees to browse on. It’s hard to imagine that a plant can defend itself from a moose!
We were on the 45 mile long island for 28 days, half of our time spent on the west end in an area called Windigo, and the other half on the east end near the Daisy Farm campground. Windigo is one of the visitor centers in the park and here we stay with the other researchers and pilots in one of the employee bunkhouses where we draw water from a hole in the ice on Washington Harbor, heat with wood, and use a generator for electricity. At Daisy Farm, Lisa and I live in a 12’ x 24’ ranger cabin situated only 20’ from the lake where we heat, cook, and light our cabin with propane fuel and draw water from Rock Harbor.
For more information on the wolf moose study click on this link www.isleroyalewolf.org and and click ‘Winter Study”.