The thing that strikes you immediately about the exhibit of "Art Depicting Birds" opening this weekend at the National Collection of Fine Arts is that every one of the 47 artists represented is an expert on his subject. The artistic skills are awesome, but are overshadowed by the obvious authenticity of the birds and their habitats.

One of the museum guards, a lifelong outdoorsman, marveled at a sculpture of a wood duck as it was being carried through the halls to the exhibition rooms. It must, he suggested, have been freeze-dried immediately after it was shot, and taken to a superb taxidermist. He had to touch it before he could accept that it was a wood carving.

Many of these artists are primarily ornithologist -- Owen J. Gromme, who contributed a marvelous oil titled "Marshland Elegy," was formerly curator of birds and mammals at the Milwaukee museum; every birder knows Roger Tory Peterson, here represented by a painting of puffins; Don Richard Eckelberry, here with "Bobolink Field," is a fellow of the American Ornothologists' Union and is best know for his 1,250 illustrations for Pough's three-volume "Audubon Field Guide." Eckelberry, incidentally, will lecture at the Collection Saturday at 2 on wildlife art techniques.

The 47 works at the show came from last fall's annual invitational show at the Woodson Museum in Wausau, Wisconsin, and it is to be hoped that this will become an annual followup.

It could be argued that the sculpture in the show is, of necessity, too realistic -- verite -- to qualify as high art, but not so the paintings. None of these is birdwatcher-guidebook; all are masterful representational creations, some even impressionistic. Kenneth Carlson's "Teton Winter -- Trumpeters" has to rank with the time-tested masterworks eleswhere in the National Collection. The birds are on exhibit through May 6.