February 2008

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.






Humans and fish are similar in that they rely on the senses of taste, smell, sight, hear and touch to live and cope with their surroundings. However, fish also have a sixth sense. What is it?

Fish have a built-in motion detector called the lateral line, a row of tiny holes that run along each side of the body. The sensitive hairs inside each hole help detect the location and direction of vibrations in the water. This is especially important to anglers. The sound and movement of bait in the water attracts attention. Once at an anglers lure, fish will use their other five senses to determine if the bait is something that sounds like, feels like, looks like, smells like and tastes like something they might usually eat. While the lateral line helps fish find a meal, it keeps them avoid becoming one, too. The lateral line also enables a school of fish swim together without bumping into each other.

- Jenifer Matthees, DNR aquatic education supervisor


Not every bird species migrates from Minnesota to warmer climates down south before winter sets in - some stay behind. Is there anything that can be done to help these birds survive winter?

A good way to provide the nutrition birds need in the winter is to provide three main choices of food - large seeds such as black oil sunflower, small seeds, and suet or peanut butter mixes.
Black-oil sunflower seeds have the greatest appeal to the broadest variety of winter birds and contain a high-energy content. In addition, water is a critical ingredient of a winter-feeding program. There are birdbaths with heating elements and thermostats available from bird feeding supply stores. The heated water is primarily for drinking. People should not worry about birds freezing if they bathe on a cold winter day because native song birds are smart enough not to immerse themselves in the water when the wind chill is 40 below. For more information on winter bird feeding, check out the DNR Web site at mndnr.gov.

- Lori Naumann, DNR Nongame Wildlife Program


I recently noticed open water on my normally ice-covered lake. What is the cause?

My recollection is that there are periodically similar reports, lakes where areas of open water show up where they haven't occurred in previous years. I think the most logical explanation is a large influx of groundwater, probably associated with periods of above normal precipitation. Ground water is warm enough (about 50 degrees F) and if the inflow is sufficiently large, the "warm" groundwater plume will rise all the way to the lake's surface before it cools to 40 degrees F (as long as the water is above about 40 degrees F, it is the least dense layer in the lake and will tend to rise). If the "warm" ground water plume reaches the surface, the plume either erodes the ice or keeps it from forming.

- Dave Wright, aquatic ecologist, DNR Ecological Resources


Our snowfall totals this winter have made cross-country skiing ideal for the first time in years. What sort of skiing opportunities are available throughout Minnesota?

The DNR supports more 150 cross-country ski trails statewide, totaling more than 1,800 miles. These trails are a great way for people to see the unique natural environments of Minnesota - from the prairies to the northern hardwood forests. Skiers are required to purchase and possess a ski trail pass before skiing on state or grant-in-aid trails. Ski passes cost $5 for the daily, $15 for the annual, and $40 for the three-year pass. Most state parks and some trailheads sell daily passes, but not all of them do, so it is recommended that skiers pick up their passes at any of the more than 1,800 DNR electronic licensing agents statewide or on the DNR's Web site. The DNR Web site has an updated list and information on every state and grant-in-aid ski trail in the state: mndnr.gov/skiing.

- Andrew Korsberg, DNR Trail Program coordinator


DNR Question of the Week Archive