History of Moose on Isle Royale
1949-1980
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Moose came to the island in the early 19th century. Their population has never been constant, always going up and down. From 1959-1969, the moose population doubled from 500 to 1,000, and by 1980 the moose population increased to 1,500 and the wolf population jumped to 50.
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1980-1989
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In the early 1980s the wolves were on the rise and moose were on the decline. As wolves were increasing they were killing moose faster and more often. But in a couple of years the wolf population dropped from 50 to 14 from disease. The moose population instantly began to shoot up.
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1990-1999
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The moose were at the highest than ever before in their population numbers. Nearly 2,500 moose were recorded on the island, but this posed a problem. The moose overharvested heavily on the trees and shrubs that they eat. In the winter of 1996, the moose population dropped from 2,500 to 500 from lack of food sources, mainly the balsam fir ("All About Moose").
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2000- Present Day
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Moose began to slightly increase after the winter of 1996, but wolves were also increasing for a new wolf that came to the island. This caused more moose to be killed and would decrease the moose populations to the lowest levels ever seen on the island. Moose were below 500 in the early to mid 2000s and it looked very bad for them. But then wolves began to decline again in 2006, and ever since then the wolves have been decreasing and moose have been increasing.
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What effects the Moose Population?
Balsam Fir Tree Density Study
Thomas Brander, an ecologist studying balsam fir on Isle Royale, set up nine locations on the island where balsam fir quantities and saplings were high. In six of nine locations, balsam fir was damaged so badly that the trees had no chance of growing back. At the other three locations, the saplings and balsam fir trees were not damaged as bad and could regrow following the next spring and summer. This study showed that when the predator (wolf) declined in population it affected the prey (moose) as their population rose and caused overharvesting of balsam fir on the island. This study happened in 1990, while the moose population was rising to its all time high of 2,500 and before the crash of the moose population in 1996.
(Brander)
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Balsam Fir Tree
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The Moose Struggle in the 1990s
This scenario above describes was happened to the moose population during the 1990s. The wolf population was starting to increase during the 1990s, and the already high moose population was suffering from overharvesting. As the wolves increased in population, the predation increased because wolves were killing more moose. This caused the moose population to decrease (“The Population Biology of Isle Royale Wolves and Moose: An Overview”).
This scenario above describes what happened to the moose population during the winter in 1996. As the moose population rose, they overharvested, which caused a food shortage during the winter. It weakened them, making them more vulnerable to be attacked by wolves. This increased the predation rate, and decreased the moose population (“The Population Biology of Isle Royale Wolves and Moose: An Overview”).
Current Status On Moose
Currently the moose population is rising on the island, and is about 1,100. With there only being three wolves on Isle Royale, the predation rate is very low. The moose population will continue to rise on the island, unless the wolf population can make a comeback ("About The Project: Overview").