Birds Lost from a Giant Sequoia Forest during Fifty Years

Not all forest bird species breeding on Redwood Mountain, Tulare County, California in the 1930s are still there in the 1980s. Over the 50 years virgin giant sequoia forest of the saddle and east slope (within Kings Canyon National Park) remains unchanged but has lost the Olive-sided Flycatcher (Contopus borealis). The mixture of old and second-growth sequoias of Whitaker's Forest, where pines and undergrowth were removed and snags eliminated, is missing the Mountain Quail (Oreortyx pictus), Flammulated Owl (Otus flammeolus), Northern Pygmy-Owl (Glaucidium gnoma), Spotted Owl (Strix occidentalis), Hairy Woodpecker (Picoides villosus), and Olive-sided Flycatcher. Though unchanged today, the riparian alders of Eshom Creek on the west slope have lost Swainson's Thrush (Catharus ustulatus). Drastic logging by Sequoia National Forest has driven all of the above from the west slope ponderosa pine forest that surrounds Whitaker's Forest. New birds established at Whitaker's Forest by 1986 are the Common Raven (Corvus corax), House Wren (Troglodytes aedon), and Lincoln's Sparrow (Melospiza lincolnii). Intrusion of Brown-headed Cowbirds (Molothrus ater) has begun without yet affecting two abundant species of vireos. The Pileated Woodpecker (Dryocopus pileatus) is reduced; the Winter Wren (Troglodytes troglodytes) has greatly increased. I attempt to explain avifaunal changes by comparing habitats over the 50-year interval. Disappearance of the flycatcher and thrush from unchanged, prime habitat must be caused by destruction of corresponding forests in Central America, where these birds maintain their winter territories.