Behavior and vocalizations of the Caura and the Yapacana Antbirds

The first detailed information on the vocalizations (including the first so und spectrograms) and natural history of the Caura Antbird (Percnostola cau rensis) and the Yapacana Antbird (Myrmeciza disjuncta) are presented. The C aura Antbird was studied in the Serrania de la Cerbatana, edo. Bolivar, Ven ezuela, where it inhabits humid foothill forest dominated by large rocks. C aura Antbirds specialized in foraging on or beneath rocks, a behavior unusu al among the Thamnophilidae. The Yapacana Antbird was studied at a site alo ng the south bank of the Rio Ventuari, edo. Amazonas, Venezuela. These antb irds were locally abundant in a specialized stunted woodland that grows on white sand soils. Based on newly described vocal characters, the closest re latives of P. caurensis appear to be P. leucostigma and P. schistacea, wher eas M. disjuncta has no apparent close relatives and probably merits placem ent in a monotypic genus.