AS long as there have been amateur naturalists, the field notebook has been an indispensable tool. Where else to note the abundance of salamanders in a particular summer, or the paucity of bluebirds?

Gradually, binoculars have also become an absolute necessity for birders, and more recently for butterfly-watchers.

The latest technological innovation for the trampers of woods and fields, though, is the interactive online database.

Amateur observers of nature are being recruited by professionals to keep an eye on their natural neighborhoods, to count hawks and other birds, to report butterfly sightings. The nature lover's newest role is collector of data.

''We are in the midst of a sea change in the way people view themselves in relation to the environment,'' said John W. Fitzpatrick, director of the Cornell Lab of Ornithology. ''And technology is making the difference.''

The specific technology he is referring to is the personal computer connected to the Web. Several conservation organizations are promoting a variety of ''citizen science'' projects that make use of amateur observations. One of the first such projects, the Audubon Christmas Bird Count, dates back a century. (This year's begins tomorrow and continues through Jan. 5.) But in the last five years a number of new efforts have been started, all based on the capacity of the Web both to receive data from just about anywhere and to display it quickly and clearly.

A bird-watcher can now enter the sighting of a cardinal at the backyard feeder, or a kettle of hawks over a nearby mountain, directly on a home computer. Analyses of the data are available in tables, maps and other forms, so contributors see how their data is being used. The hope, Dr. Fitzpatrick and others say, is that the ability to share with many others what you have seen and counted -- nuthatch, redheaded woodpecker or tiger swallowtail (a butterfly) -- will be an incentive to go out and look again. The ultimate indoor technology, known to cause eyestrain, headaches and precipitous loss of a good tan, is being used to get people to go outside.

Frank Gill, the director of science at the National Audubon Society, has worked hand in hand with Dr. Fitzpatrick and the Cornell Lab, a membership organization that is affiliated with Cornell University, to create some of these projects.

Dr. Gill said that the cooperation began a few years ago. ''I said, 'Fitz, let's do something together,' '' he recalled. The two organizations created a project for absolute beginners based on the capacity of the Web, the Great Backyard Bird Count. To take part, all anyone has to do is look in a backyard or a nearby park, and then log on and report what was seen. The fifth annual count will take place in February and is open to everybody. The online directions are designed for beginners, with lists of birds likely to be found in specific areas and a question that lets a participant estimate how sure he or she is of the identification. There are also filters that make it unlikely that sightings of Andean condors in Central Park will make it into the compilation of data.

The event has ''motivated people to be outside and connected with birds at home in a way they wouldn't have otherwise,'' Dr. Gill said. What makes participation appealing, he said, is that people can share what they observe with others immediately and see their information become part of the whole.

Suzanne Patterson of Cold Springs, Calif., in the Sierra Nevada, is a great fan of online birding. She is a member of her local Audubon Society chapter but said she never had the time to go on birding outings or take part in the Christmas count.

The backyard count was different. ''The computer made it so easy,'' she said. And she had something exciting to report: 60 to 80 evening grosbeaks each day, something so unusual in her area that it counted as an irruption, an unusual migratory pattern.

Ms. Patterson said she became ''something of a fanatic.'' She ended up trading e-mail with people at the National Audubon Society and would check the count on the Web site to see the changes in distribution maps.