Introduction

Rarity is the hallmark of the Kirtland’s Warbler. It has always been regarded as one of America’s rarest songbirds since its discovery on 13 May 1851 when a migrating male was taken on the farm of Jared P. Kirtland near Cleveland, Ohio. Rare in absolute numbers, it is difficult to find in its breeding range, on its wintering grounds, and in migration between the two. Formally described by Spencer F. Baird (1852), another half century passed before its nesting ground was discovered in northern Lower Michigan in 1903. In the meantime, five more specimens were taken in migration in Ohio and Michigan, and at least 71 in the Bahama Islands in winter, establishing these islands as the winter home. Its rarity is a consequence of its small and specialized breeding habitat—young jack pine (Pinus banksiana) forests—and perhaps its narrow requirements on its nonbreeding grounds. In addition, brood parasitism by Brown-headed Cowbirds (Molothrus ater) severely reduced its breeding success in this century until recent control efforts reduced cowbird numbers on the nesting grounds. This is a well studied warbler; Huber (1982) cites 800 published works on the species, Stone (1986) 300 listings and maps.