Nictitating membrane: It's like a third eyelid, only horizontal, opening and closing like an elevator door. It lies beneath the main eyelids. Birds blink with the nictitating membrane to moisten and clear the eye. They tend to close their true eyelids only when sleeping.

Book in brief

"Owls of the North" (Stoneridge Press, $16.95) is a slim handbook on one of the most compelling bird families found in Minnesota.

Author Dave Benson, a Duluth naturalist, gives you a rainy-afternoon's worth of owl information that's clearly written and crisply offered. There also are plenty of photographs, an index, a bibliography and suggestions for additional reading.

Chances are there is an owl of one kind or another in your neighborhood. Benson offers you a well-crafted opportunity to become better acquainted with that neighbor.

JIM WILLIAMS

Lure the birds

Offering a variety of seeds improves your chances of attracting more birds and bird species. Having separate feeders for each kind of seed also helps attract birds because it lessens competition among birds for feeder space. Ask your bird store for suggestions on standards or poles from which to hang the feeders.