Name: __________________________________ Period: _____ APES ACTIVITY - The Moose and Wolves of Isle Royale A Study of Population Change Isle Royale is a small, isolated island in Lake Superior, lying between Michigan, Wisconsin, Minnesota, and Ontario, Canada. It is a U.S. national park and wilderness preserve and remains relatively untouched by outside influences. The moose and wolves of Isle Royale have been studied for more than five decades, the longest continuous study of any predator-prey system in the world. Moose first arrived on the island in the early 1900’s, when a small herd swam there from Minnesota. Their population grew relatively unchecked until the arrival of a single breeding pair of wolves, crossing the ice from Ontario in the winter of 1949. The graph below shows the wolf and moose populations of Isle Royale from 1959 to 2010. What is not included on the graph is the growth of balsam fir trees on the island, which constitute the major food source for the moose population. Please add the balsam fir tree data on the opposite page to the graph above. You may want to translate the scale of “low, below average, average, above average, high, very high” into relative values for graphing. Add axes or other descriptors as necessary. YEAR 1960 1965 1970 1975 1980 1985 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 MOOSE POPULATION 637 773 1522 1462 861 968 1216 1313 1590 1879 1770 2422 1163 500 699 750 850 900 WOLF POPULATION 22 28 18 41 50 22 15 12 12 13 17 17 22 24 14 25 29 19 BALSAM FIR GROWTH RATE average above average low low average very high average high below average average average below average below average average average average average average Answer the following questions. 1. In what year did the wolf population peak? What impact, if any, did this have on the other two organisms? Provide a possible explanation. 2. In what year did the moose population peak? What impact, if any, did this have on the other two organisms? Provide a possible explanation. 3. After the initial colonizations, the island populations of wolf and moose remained isolated from the mainland for many generations. Given what you know about genetics and population biology, how would expect the health of the island wolf and moose populations to compare to similar populations on the mainland? Explain. (The answer may be different for wolf versus moose populations.) 4. In 1980-81, canine parvovirus was brought to the island by a park visitor’s dog. What was the impact on the organisms in the island ecosystem? Provide a possible explanation. 5. The winter of 1996 was the harshest winter on record for the island, and that spring saw a severe outbreak of moose ticks. What was the impact on the organisms in the island ecosystem? Provide a possible explanation. 6. During the winter of 1997, a single male wolf was able to cross the ice from the Canadian mainland to the island, where he began to breed with the island wolves. Some naturalists believe that this altered the balance of the moose-wolf relationship. a. Why would this be? b. What evidence, if any, do you see for this in the data above?
