Q. How do you tell the sex of a fish?
A. Not very easily, says DNR aquatic education specialist Roland Sigurdson. Female fish are generally larger than male fish of the same age and species--so if you catch a really big fish, chances are it's a female. In some species, such as sunfish, males are more colorful than females, particularly during the breeding season (April-June). For species such as walleye and channel catfish, the only real clue is if the fish is round with eggs.
Q. Growing up in the Cambridge area in the 1960s, my friends and I spent endless summers on the Rum River, fishing, swimming, boating, chasing crayfish, and diving for clams. A couple of times, we found a large, jellylike object attached to branches of submerged trees and about the size and appearance of a large pineapple. Any ideas what it was?
A. It likely was a colony of bryozoans, says DNR aquatic invertebrate biologist Gary Montz. These microscopic animals make jellylike tubes and attach them to sticks, rocks, and other submerged objects. They connect their tubes together into colonies that can be as big as a volleyball. The animals themselves live in the tubes and extend their tentacles out to capture even smaller microscopic organisms for food.
Each fall the bryozoans begin to die off, but create overwintering "eggs" that will form new colonies the next year. When the colony is dying, gas produced by decomposition may cause it to float loose, sending gelatinous globs floating down the river.
Montz says bryozoans are quite common in many Minnesota waters, ranging from large rivers to lakes to small ponds. They are not toxic, venomous, or harmful. They don't really seem to cause problems for people, except for the "ick" factor and occasionally clogging underwater screens or pipes.
"Just another of the really strange life forms that are in our waters that most people don't even know exist," Montz says.
Q. While checking our cabin on Upper Red Lake, we noticed two dead pine grosbeaks on the deck. Apparently they struck the glass patio door. Is there anything we can do to prevent this? The area has high wind, so anything free hanging will not stay. Last summer we put a reflective film on the doors to minimize heat transfer in the hot months. This may have made a mirror effect from the outside.
Mike and Nancy Melin
A. The reflective film probably is a problem--remove that if possible, since birds can't distinguish the real outdoors from a reflection. Here are some other things you can try:
- Add falcon silhouettes or other stick-ons to the inside of the window to break up the reflection and add a scare element. (Some folks have even had luck with a suction-footed Garfield doll.)
- Hang pieces of white string every five inches across the window.
- Use a bird screen or other commercial devices. A Web search using the key words "bird screens" will get you to some vendors.
Q. Three summers ago while working in our heavily wooded yard, my husband and I were dive-bombed by a pileated woodpecker. The bird continued its noisy assault until we went indoors. Three pileateds have since taken up residence year-round. They play on our bird feeder and suet blocks like a trapeze. We love having them around, but wonder what we can do to protect ourselves from their dive-bombing. Are they likely to actually attack us? They do seem serious about their dislike of us.
A. Folks around here are pretty envious of you. Pileated woodpeckers are usually quite skittish and avoid human contact. That said, it's not uncommon for some bird species to dive-bomb invaders (you) who enter their territory during their courtship and nesting seasons. Although she has never heard of a case of humans being attacked by pileated woodpeckers, DNR wildlife educator Jan Welsh recommends you wear a hat (or a hockey helmet) in the yard if you are concerned. She suspects the birds may begin to tolerate your presence as time passes.
Q. My boyfriend tells me that when tomatoes ripen, chipmunks will eat holes in the bottoms to get the juice. Is this true? He wants to set traps for them. Is there some other way to keep them away from the plants?
A. It's true--chipmunks love tomato juice. Try placing a large basket made from 1/2-inch hardware cloth around each plant, digging it into the soil a bit so the chipmunks can't crawl underneath. For more advice on controlling wild critters, see DNR - Living With Wildlife.