Natural Curiosities - Minnesota Conservation Volunteer

Q. Over the past years, there has been a large increase in the number of crows in our area. As a result, it seems, we see very few other birds. Does the DNR monitor the crow population? What's happening?

Mick Justin
Nisswa

A. Although the DNR does not formally count crows, many people have noticed an abundance of these birds in recent years. They're doing so well, says DNR Nongame Wildlife Program supervisor Carrol Henderson, because they are clever and adaptable, and they fit well into the artificial environments we humans create. Where other birds might see development as habitat lost, crows see it as a new source of food (roadkill, dumpsters, parking lot litter, etc.). Crows can cause trouble for other birds; in fact, they've been known to eat baby robins and other songbirds. If you'd like to discourage them from staying in your area, shoo them away from your bird feeders, pick up food trash, and keep garbage cans and dumpsters closed.

Q. Conversation topics at the coffee shop run from A to Z. A couple of weeks ago, the topic of lake flipping came up. It seemed there were as many opinions on how and why lakes flip as there were coffee drinkers. Would you please tell us when, how, and why lakes flip?

Jerome R. Bradford
Monticello

A. Each spring and fall, Minnesota lakes undergo a process called turnover. This natural process is good for the lake because it helps distribute nutrients and oxygen throughout the water, thus improving its ability to support plants, fish, and other living things.

Turnover happens because water is most dense at 39 F. In the fall, the surface of the water cools. As it cools, its density increases and it sinks while the warmer, less dense water below rises. This process continues until the entire lake is about the same temperature. In spring, as the ice on the surface of the lake melts, it produces liquid water that is colder (thus denser) than the water below it. This denser layer sinks, again mixing nutrients and oxygen.

Q. How did "crab" apples get their name?

Lynne Bryant
Maple Plain

A. According to Webster's New World College Dictionary, the "crab" in crab apple is related to the Middle English word crabbe, which means wild apple. The link among the apple, the crustacean, and the moody person is probably that the apple is sour, the crustacean can seem irritable, and the moody person is often both.

Q. While hiking in Lakeville last January we saw about 30 robins in a small depression between two hills. Is this normal? We know robins can stay all winter, but why cluster in a depression, which must be colder than the surrounding hillside?

Jay and Diana Dombrowski
Lakeville

A. In winter robins gather where they can find food, says DNR wildlife educator Jan Welsh. These birds were probably feasting on fruits that become edible after they freeze and thaw—crab apples or berries from plants such as bittersweet, viburnum, or sumac. Cold is relatively irrelevant: Birds that winter here generally can make enough body heat to stay warm as long as they have something to eat.

Q. My father lives on Otter Lake by St. Cloud. He said it is a deeded lake and would like to know what that means. Does he own part of the lake?

Betty Johnson
Edina

A. There is no formal classification known as "deeded lake." However, there are circumstances in which a landowner owns a lake or part of a lake on his or her property.

In Minnesota, lakes that are "navigable" by federal definition and were meandered (traced around) by surveyors in the 19th century are public property up to the natural ordinary low-water level. If a lake is non-navigable and meandered, the lake may be split up by the courts among the surrounding landowners, though this rarely happens. Lakes that are non-navigable and nonmeandered as a rule of thumb belong to whomever holds the deeds to the surrounding land, according to DNR senior hydrologist Ron Anderson. There is an Otter Lake on record in Stearns County that is non-navigable and nonmeandered. Your dad can check his deed or ask a lawyer to see if he owns any or all of the lakebed.

Q. A dog I know has a cunning ability to locate, smear herself with, and eat wildlife defecation. I'm guessing this is her way of masking her predator scent since she is a descendant of wolves. Would you agree?

Myron Salonek
Plymouth

A. No one knows why canids (members of the dog family) roll in dung. According to Jessica Edberg of the International Wolf Center, possible reasons include masking their scent and providing information to others in the group. Eating dung may be a sign of boredom. Check with your veterinarian on that one.