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Natural Curiosities

I was fishing for bass in Lake Beltrami on a rainy day when I noticed a large fish head sticking out of the water. The fish skimmed along the surface for about 10 yards before submerging. It looked as if it were trying to breathe. It resembled a large largemouth bass or even a dogfish. What was this fish and what was it doing?

Riley Lealos
East Grand Forks

DNR aquatic education specialist Roland Sigurdson thinks you were observing a bowfin (also known as dogfish). Bowfins come to the surface to fill their swim bladders with air. They can use that air as a source of oxygen to supplement what they extract from the water with their gills. According to Sigurdson, longnose and shortnose gar do this as well.

Four wolves visited my field in Lutsen for about four days last August. It appeared that mange had affected the group: One was completely bald, one about half bald, and the other two were somewhat affected. What is mange? How will it work out for these wolves? Is there something I could have done to help them?

John Wolf

Mange is caused by a tiny invertebrate called a mite, says DNR wolf biologist John Erb. Mites burrow into the skin (and also lay eggs), which causes irritation, scratching, and probably secondary infections. Animals with mange typically lose a lot of hair, and their skin becomes very thick and wrinkly. Mange spreads mainly through direct contact, though it also might be transmitted when animals use dens where an infected animal lived. Animals with mange often die of hypothermia, starvation, or secondary infections. There are treatments for pets with mange, but there is no easy way to treat wild animals.

What causes flowing spring water, and why do people think this is very good drinking water?

Eugene E. Studt

Springs occur across Minnesota, says DNR regional groundwater specialist Jeff Green. They range in size from those producing a few gallons per minute to those discharging thousands of gallons per minute from caves in southeastern Minnesota. A spring is fed by an aquifer (layer of rock or soil that yields water to a well). Water moves through an aquifer and eventually discharges into a stream, river, or lake. When it comes out in a concentrated flow, we call it a spring.

Some people think spring water is good for you because it contains minerals. Unfortunately, it can contain other things too. Spring water that discharges from fractured rock may contain bacteria and may not be safe to drink because fractures don't filter water very well. A number of cities in southeastern Minnesota used springs as their original water source but later abandoned them in favor of wells because of contamination concerns.

I saw a sparrow following a robin on Grand Avenue in St. Paul. Every move the robin made, the sparrow followed a few hops behind. Finally the robin leaned down and the sparrow took something out of the robin's beak, then the robin flew away. What was happening here?

Jennifer Adam
St. Paul

DNR nongame wildlife program supervisor Carrol Henderson suspects the "sparrow" was actually a young brown-headed cowbird. Cowbirds lay their eggs in other birds' nests; and when the young hatch, the adoptive parents care for them as their own. "Blended family of sorts," Henderson says.

The last couple of years a small, light green treefrog has made its home on my window well or under a ledge to the door of the root cellar. Do frogs return each year to the same place?

Brian Olson

Your visitor is probably a gray treefrog (Hyla versicolor), according to DNR amphibian and reptile specialist Carol Hall. Gray treefrogs' large toe-pads help them climb trees, where they feed on insects and  take shelter in  cavities.  They also climb buildings and feed on insects attracted by lights.  Gray treefrogs emerge from ponds as tiny green frogs, less than an inch long. As they grow, they develop a mottled pattern and their color  shifts between green  and gray.  They overwinter in leaf litter and tolerate cold  temperatures  by making their own antifreeze.  Frogs can live for many years, so it could indeed be the same one coming back each summer to visit your door. 

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