Spec-mapping of territories was used to document the restriction of nineteen bird species to thickets of bamboo (Guadua weberbaueri) in lowland forests in southeastern Peru. These species were defined as bamboo specialists. An additional seven species showed a preference for such thickets, but also used other habitats. These results correspond with previous, qualitative descriptions of the habitat preferences of bamboo specialists. At least four specialists are restricted to thickets throughout their entire geographic range (obligate bamboo specialists); another nine specialists may use other habitats sparingly away from southeastern Peru (near-obligate bamboo specialists); the remaining six species are frequent users of habitats lacking bamboo away from southeastern Peru (facultative bamboo specialists). The nonbamboo habitats used by the 13 near-obligate and facultative specialists are predominantly dense habitats with low canopy cover, including treefall gaps and early successional vegetation along rivers. The obligate and near-obligate specialists generally have small geographic ranges centered in southwestern Amazonia; a few have sister taxa in southeastern Brazil that are also bamboo specialists suggesting a common evolutionary history. The facultative specialists are generally mote widespread. Bamboo specialists are more abundant in bamboo habitats than are other bird species in more generalized habitats.