November 2014

The DNR communications team works with agency experts to develop the weekly questions and provide the answers. This feature addresses current DNR issues, interesting topics, or the most frequently asked questions from around Minnesota.


Q: I noticed the DNR eagle cam is back online. Do bald eagles in Minnesota migrate for the winter, or do they stay on their summer nests?

A: Many Minnesota bald eagles do not migrate. As long as they have access to open water, they can and do stay here all year. In fact, with the installation of the eagle cam, we have learned that eagle nests are rarely vacant. Eagles are bonded to their nesting territories, and staying around ensures that it will not be taken over by another eagle or pair of eagles.

The eagles along the Mississippi River and Hawk Ridge near Lake Superior during spring and fall are mostly migrating eagles. Most of the eagles come from Canada and use the Mississippi flyway to travel south to their wintering grounds.

Lori Naumann, DNR nongame wildlife program specialist


Q: What is the process for donating deer to a food shelf?

A: Minnesota’s venison donation program, established by the state Legislature in 2007, allows hunters to donate legally-harvested deer to a participating meat processor. There is no cost to you (the hunter), and the processor is reimbursed for each deer they send to the food shelf. The deer must be properly field-dressed with the hide intact and identified with a DNR harvest registration tag. For a list of processing locations, visit


- Leslie McInenly, DNR big game program leader


Q: Which tree species are most abundant in Minnesota?

A: Our most abundant tree species in Minnesota is the quaking aspen with an estimated population of more than 3.5 billion. The next most abundant species (in order) are balsam fir, black spruce, black ash, paper birch, tamarack, red maple, northern white cedar, sugar maple and balsam poplar.

Curtis Vanderschaaf, biometrician, DNR Forestry Division, resource assessment



Q: How can I tell when a lake has turned over in the fall, and do most fish go deeper after turnover?

A: A lake has turned over when water temperatures are the same from the surface to the bottom. The process can take days or even months to complete, depending on lake shape and depth, and air and water temperatures. The only way to conclusively know when a lake has turned over is to measure the temperature at the surface of the lake and at the bottom; if they are roughly the same temperature (within a few degrees), the lake has turned over. During the process of turnover water clarity may decrease, decaying organic material can be seen suspended in the water and there can be a sulfurous odor.

Before lakes turn over in the fall, temperature and oxygen may vary across depths. In these lakes, the waters below a certain depth may become oxygen-deficient during the summer. When this happens, fish cannot use this habitat and are squeezed into waters near the surface. After the lakes turn over, the oxygen levels are consistent from the surface to the bottom, and fish can use depths that were uninhabitable during the summer. Studies of walleye, northern pike, muskellunge, and cisco that were tagged with depth sensors have verified that these species use deeper depths after turnover.

Andy Carlson, DNR fisheries research scientist


DNR Question of the Week Archive