We do a lot of trout fishing in southeastern Minnesota as well as in the Black Hills of South Dakota, and have always wondered why trout flesh can vary in color from pink to white. We'll catch fish from the same spot on the same day that will vary drastically in color, so it seems suspect that it can be purely diet—but there seems to be no correlation to size or type of trout either. We've heard it has something to do with being wild (pink) versus hatchery-raised (white).
Mike and Vanessa Butenhoff, Savage
Flesh color in trout is related primarily to diet, says DNR aquatic education specialist Roland Sigurdson. The flesh is normally white, but a diet high in crustaceans, such as scuds and freshwater shrimp, causes it to become pink. These crustaceans contain a carotenoid compound called astaxanthin, which has an orange-yellow color.
Why the difference among fish from the same stream? The availability of food organisms varies along any stream stretch. In addition, individual trout are highly selective about what they eat. Some prefer crustaceans, while others might target an organism that does not contain astaxanthin. Many trout raised in the Minnesota DNR hatchery system are fed a diet that contains natural carotenoids for five to six months before stocking to color the flesh. Fish that have achieved sexual maturity have more vivid skin and flesh colors than those that have not matured. Males are more brightly colored than females.
While snowshoeing, it's easy to spot porcupines up in the trees. How long do they stay holed up in their den, or how often do they have to come out to eat? I notice they seem to alternate between white pines and hardwood trees. Is this due to their dietary needs?
Craig Larson, Bemidji
Porcupines stay active all winter rather than hibernate. Several porcupines may share a den. They are a lot like squirrels (and many of us humans), says DNR wildlife educator Jan Welsh—they come out when it's warm and hole up when it's cold. They are mainly active at night. In winter, porcupines only forage in a two-acre area around their den site. While white pine is a preferred food, they'll eat bark from any tree in this small range. In summer, they eat a wider variety of herbaceous and woody plant material.
Last June a mother duck proudly presented her new family to residents on Swan Lake in Pengilly. This mom had 18 ducklings under her care. How did this happen? Did she take on other families? How many eggs could a duck possibly lay, much less sit on until they hatch?
Sue Patterson, Pengilly
The basic issue here is that ducks can't count, says DNR wildlife educator Jan Welsh. Ducks like woodies and goldeneyes are often victims of dump nesting: A female will lay her own eggs, then when she flies out of her nest box, other hens stop by to drop an egg in there too. Before you know it, the hen is incubating 30 eggs and presto . . . a giant batch of babies. If you're putting up nest boxes, it's a good idea to mount them back to back on posts so the birds won't see each other leaving and get ideas.
My dad caught this fish on Lac qui Parle Lake. He usually fishes for walleyes, but in early spring he was fishing for crappies. He says that about two years ago he caught one of these, but this year he has caught three or four. Could someone tell us what type of fish this is? He said that it had teeth.
Paul Hodge, Hanover
How about three kinds of fish? DNR fish experts who looked at your photo think it's a hybrid sunfish, possibly a "trybrid." The cream-colored margins on its fins are indicative of the green sunfish and the reddish margin on the opercular cover indicates some pumpkinseed genes, while the overall look is of a bluegill. Bluegill, pumpkinseed, and green sunfish often hybridize. Some fisheries biologists speculate that habitat degradation has caused the different sunfish species to gather in high numbers in suitable spawning areas, thus increasing the likelihood that hybridization could occur.
Why would an owl kill a rabbit in our yard, then leave it dead and not take it for its meal?
N. Golubski, Pine City
DNR wildlife educator Jan Welsh suspects the owl was frightened away by something, perhaps a dog or a yard light, right after it made its kill. Owls are not very comfortable on the ground in the open, so they will readily give up a meal if something startles them.
