Bird-watching doesn't take much in the way of equipment or costs.

If you're not yet, it's easy to get started with birding.

Whether you're curious about who's showing up at your bird feeder or if you'd like to be involved in a more active form of bird-watching, "The Sibley Guide to Birds" (Knopf, $35) should be in your reference collection.

David Allen Sibley's book is notable for his truly astonishing illustrations Ñ nearly 7,000 in all. The guide is also well-organized and easy to use. Every beautiful, informative page in this book is a delight, a masterly work by one of the nation's top painters of wild birds.

"Of a Feather: A Brief History of American Birding" by Scott Weidensaul (Harcourt, $25) is another must-read for the would-be birder. The story of how birding grew in America from the days of the Pilgrims to today is as compelling as a good novel.

You'll also want to consider participating in the Cornell University Lab of Ornithology's Project FeederWatch (www.birds.cornell.edu/pfw/index.html). The Audubon Society's Christmas Bird Count (www.audubon.org/bird/cbc) started on Dec. 14, but you can keep an eye on the progress on the Web site (through Jan. 5, 2008).

These two winter projects have been running for years now and let "citizen scientists" do their good deed for the birds of the world and those who study them.