Introduction

The Green-tailed Towhee remains one of the more poorly known North American birds, despite being fairly common throughout much of its range. Lack of knowledge of the basic life history and ecology of this species may be the result of its secretive nature, and the fact that individuals spend much of their time on or near the ground in thick, shrubby habitats. While Green-tailed Towhees are often difficult to see, they give their presence away with characteristic ascending, catlike Mew Calls, and breeding males become conspicuous when singing their diverse Song, which consists of short phrases of jumbled notes and trills.

Breeders prefer species-rich shrub communities within shrub-steppe habitats, and disturbed and open areas of montane forest, often created by forest fires. The bulky nests of this species are concealed in shrubs, but often are prone to predation. Pairs may renest as many as 4 times a season following nest failure, initiating clutches as late as mid-July. In winter, individuals are common in dense mesquite (Prosopis spp.) scrub habitat along desert washes. Here they associate with other species in flocks, often feeding using their characteristic bilateral scratching technique.

Across its breeding range, the Green-tailed Towhee appears to be most common in northwestern Colorado, northeastern Utah, the central Sierra Nevada, and montane southern California (Price et al. 1995). The species may be poorly sampled by Breeding Bird Survey methods, however, and may be equally abundant in other areas. Breeding Bird Survey data suggest that populations have been stable overall since 1966, with no significant broad trends. Conflicting impacts of humans on towhee breeding habitat, including negative effects of fire suppression but potentially positive effects of logging, may influence the stability of towhee populations overall. Despite this general stability, towhee populations may be both decreasing in central Colorado, and increasing in western Colorado (see Demography and populations).

The Green-tailed Towhee remains an understudied but characteristic species of desert, shrub-steppe, and disturbed montane forest areas—widespread habitat types—of western North America, making it a unique candidate for a variety of studies. Most of our knowledge regarding the natural history of the Green-tailed Towhee comes from anecdotal observations, and even these are limited in the ornithological literature. Detailed studies of breeding biology, from northeastern Utah and the Mogollon Rim, Arizona, provide important insights into reproductive success (Martin and Li 1992, Martin 1993b), as well as good information on basic life history, including phenology, nests, nesting-cycle periods, young birds, and parental behavior and care (Dotson 1971, Martin and Li 1992, Martin 1995). Breeding-season habitat requirements are understood well (Wiens and Rotenberry 1981, Sedgwick 1987, Knopf et al. 1990), while important data on nest sites and microhabitat come from Martin (1993a, 1996, 1998). Future investigation of migration and winter ecology, behavior, and habitat associations will fill major gaps in our knowledge of this species.