Climate Checks Moose Population
Isle Royale, Lake Superior

The isolation of Isle Royale in Lake Superior has led to its relatively simple food web. Here, wolves eat mostly moose, and moose eat mostly balsam fir. Since 1959, scientists have consistently studied the interactions of these three organisms on Isle Royale to understand what factors influence population.

This year, the moose population was measured at 450 individuals: half of what it was in 2003. Unusually warm summers of late have stressed the moose, making them more vulnerable to predation. The effects of this climate change are ringing throughout Isle Royale’s food web. Because the heat-stressed, sickly moose are easier to catch, the wolf population has grown with the increased food supply. Balsam fir is also recovering with fewer moose around to eat it.

Researchers
Rolf Peterson/John Vucetich, Michigan Technological University

Image Credits 
North America/Lake Superior, August 2004 (Blue Marble Next Generation: satellite: NASA Terra, sensor: MODIS)
Isle Royale (satellite: NASA Landsat 7, sensor: ETM+)
Wolf chase (www.isleroyalewolf.org)
Wolf (Gary Kramer/USFWS)
Moose (2) (Donna Dewhurst/USFWS)
Isle Royale shore (EPA)