Introduction

During the historic Lewis and Clark expedition, Meriwether Lewis wrote on 20 July 1805, “I saw a black woodpecker (or crow) today… it is a distinct species of woodpecker; it has a long tail and flys a good deal like the jay bird” (sic, Thwaites 1905). Subsequent observations of flight and vocalization reminded him of the Red-headed Woodpecker (Melanerpes erythrocephalus) he knew from his home in Virginia. A few years later the ornithologist Alexander Wilson, working with skins that Lewis and Clark’s expedition had provided, described this species in his American Ornithology and named it Lewis’s Woodpecker in honor of his fellow naturalist (Snow 1941, Farrand 1992, Mearns and Mearns 1992).

Since then, Lewis’s Woodpecker has continued to intrigue ornithologists. Using slow wing-beats, it frequently engages in prolonged glides and complex aerial maneuvers in pursuit of flying insects. It is opportunistic in its feeding habits, eating mostly insects in summer but switching in winter to acorns and other nuts, which it often stores in bark crevices for later consumption. Aggressive encounters, sometimes over stored food, are well documented between Lewis’s Woodpecker and its congeners the Acorn Woodpecker (M. formicivorus) and the Red-headed Woodpecker.

Distributed in the United States west of the Great Plains, Lewis’s Woodpecker favors open forests, ranging in altitude from low-elevation riparian areas to higher-elevation burns and pine forests. Like all other woodpeckers, it requires snags (standing, dead or partly dead trees) for nesting, although it is not anatomically specialized for excavating in wood and the trees it selects for nesting are generally well decayed.

Key studies of this species include comprehensive research on its ecology and behavior in California (Bock 1970). In addition, important information exists on habitat use (Raphael and White 1984, Vierling 1997), behavior during the nesting and winter seasons (Hadow 1973, Linder 1994), flight performance and anatomy (Tobalske 1996), plumage (Pyle and Howell 1995), phylogenetic relationships (Tennant 1991), and population trends (Sorensen 1986, Siddle and Davidson 1991).

Nonetheless, many aspects of the biology of Lewis’s Woodpecker remain poorly known or known from only limited geographic areas. The sporadic distribution and relatively uncommon status of this species within much of its range present a serious challenge for existing local-scale censusing methods. Broad-scale population trends indicate that numbers have declined markedly throughout the species’ range since the 1960s, and several examples of local reductions in distribution have been reported. Possible reasons include loss of suitable habitat, presence of pesticides in the environment, and competition for nest holes or general disturbance by the European Starling (Sturnus vulgaris).