Natural Curiosities

Q. On many deciduous trees, leaves often persist on the ends of the branches well into the winter. Why don't they drop off like the rest?

Chrystal Dunker
Mountain Lake

A. At the end of summer, deciduous trees normally develop a layer of cells, called the abscission layer, between leaves and twigs. Enzymes eat away the abscission layer, and the leaf separates from the tree. If a fungus or insect kills the leaf before the abscission layer forms, the leaf will remain on the tree, says DNR forest health specialist Susan Burks. The same thing can happen if frost kills leaves before they are ready to fall. The state of keeping withered leaves attached is called marcescence.

Some oaks and other tree species are naturally marcescent. The leaves of these trees drop off in spring.

For information on tree diseases, see Minnesota DNR - Forest Health.

Q. As I walked through the woods on our 50-acre farm along the Elk River, a strange scat caught my eye. It looked like a really large version of house cat scat and had quite a bit of fur in it. Near the river I found what appeared to be an enlarged cat track (no claw marks, not the oblong and pointed pad of a dog but the more oval shape of a cat). It was 4 inches wide by 3 inches long. How does one go about finding a specialist to identify this big cat? And what is the likelihood of its survival, with new housing developments popping up all over the place?

Michael Johnson
Elk River

A. The scat sounds like coyote. Coyotes eat lots of woodchucks, cats, and bunnies, and their scat has lots of fur in it.

Tracks and scat are hard to identify from a written description. Also, the tracks and scat might not be from the same animal. If you see another track from this mystery mammal, take a photo with an object such as a coin or pencil in the picture to help establish the scale and send it to us. We'd be happy to try to identify it.

Q. Sunny, warm September weekends provide a time to journey to one's favorite fishing hole along the exposed rocky shore of the Minnesota River and its tributaries. Tragically, fishing competes with the archaeologist using hammers and chisels to chip away rock along the river. Are studies available as to how fish react to vibrations, particularly manmade vibrations? Are fish attracted or repelled by unusual sounds?

John Manderfeld
New Ulm

A. Fish "hear" by using their lateral lines to sense vibrations traveling through water. Some, such as carp and catfish, can sense sound-particularly very low sound-extremely well. Others, including walleye and trout, are less sensitive. According to Peter Sorensen, University of Minnesota fish expert, whether whatever you're angling for is bothered by the archaeological expedition would depend on a number of factors, including species, distance, pitch, and amount of other background noise. In general, he doubts the hammering would affect your fishing success.

Q. Early settlers in northern Minnesota set out salt blocks to attract deer to make it easier to get their meat. Now highway departments spread salt on roads in winter to prevent ice. In summer they spread a salt solution on gravel roads to prevent dust. Does this cause the deer to gather around the roadways? So many are hit by vehicles.

Dorothy Clairmont
Laporte

A. DNR big game specialist Lou Cornicelli does not know of any research that shows deer tend to gather on roadways to eat salt. Even if they do, it's unlikely that would contribute to the collision problem. Deer licking salt off the road or shoulder would likely be easier to avoid than deer bounding unexpectedly in front of the path of a vehicle.

Q. I have read and heard stories of trappers starving due to lack of protein and nourishment while trying to exist entirely on moose meat. I do not understand this. Deer and buffalo meat sustained explorers such as Lewis and Clark for months. Could you please explain?

Carl Sylvester
Ely

A. University of Minnesota public health nutrition graduate student Kristi Weber, who frequently eats venison, bear, and other game, ran a nutritional analysis of various game meats and found no difference that would explain the situation you're describing. Here's her report: "All of the meats were very lean, which may have something to do with the decreased ability to sustain persons for a long time period, but the fat content of moose meat is really no different than that of the other meats. An extremely low-calorie and/or low-fat diet will be unable to sustain a person, regardless of what the food is, if the dietary intake is not sufficient enough to support daily activity and body processes."