November is a good month for nature observations.

To wit:

• There is plenty of natural food for furry animals.

• Trees are silhouetted against blue skies and fantastic cloud formations.

• Dried grasses such as reed canary, brome and big bluestem stand tall, as do herbs like common milkweed, New England aster and bull thistle.

• And winter birds such as northern cardinals and blue jays are colorful, beautiful sunsets enchant us, and new ice appears.

Excitement follows the first new ice on ponds and small lakes. So does the need for discovery, the need for skating, the need for fishing — and the potential of big danger. It takes at least 4 inches of new, solid ice in contact with stationary water for safe skating, walking and ice fishing. You don't want to fall through the ice; cold water saps body heat 25 times faster than air of the same temperature. In 32-degree water, a person will last about 15 minutes before losing consciousness.

Ice near streams flowing into or out of lakes or near springs is especially dangerous. Test the thickness of the ice first. As you do, remember that ice seldom freezes or thaws at a uniform rate. It can be 6 inches thick in one spot and only an inch thick 10 feet away.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.