Predator-Prey: Isle Royale

Isle Royale's moose and wolf populations: a classic predator-prey case study!

Isle Royale National Park on a remote island was established in 1940, and designated a wilderness area in 1976. Moose first arrive at Isle Royale around 1900. The moose population tends to increase in years with mild winters, early spring green-up, abundant winter forage, low wolf numbers and low levels of tick infestations. Wolves first arrived at the island on an ice bridge from Canada in 1940. Disease has also influenced the wolf population. Between 1980 and 1982, the wolf population experienced a sharp decline due to the canine parvovirus. The data table and graph below shows the population sizes for the moose and wolves of Isle Royale from 1959-2006. 1. What was the greatest wolf population, and when did it occur? 26 wolves, 1966 40 wolves, 1978 45 wolves, 1995 30 wolves, 2006 What was the wolf population when the moose population was the greatest? 14 wolves 16 wolves 22 wolves 40 wolves What causes the moose population to decrease? CHOOSE ALL THAT APPLY. increased wolf population harsh winters early spring green up low numbers of parasites What happens to the wolf population when the moose population decreases? The wolf population increases because there is more competition for food. The wolf population decreases because there is more competition for food. The wolf population increases because there is less competition for food. The wolf population decreases because there is less competition for food. Why is this interaction between predator-prey called a cycle? Because the populations are constantly fluctuating based on their relationship with each other. Because the populations remain steady based on their relationship with each other. Because the number of prey has no impact on the number of predators. Which factors would decrease the size of the wolf population? CHOOSE ALL THAT APPLY. a large moose population a low moose population canine parvo virus hunting on the protected island What would happen to the moose population if the wolves were removed from the ecosystem? It would remain the same. It would overpopulate, and then decrease due to competition for resources. It would decrease, and the moose would go extinct. Is the relationship between predator-prey density dependent or density-independent? Density-dependent, because population sizes directly impacts the moose and wolves. Density-independent, because there is no relationship with the population size.