Behavior and vocalizations of the caura and the yapacana antbirds
1999; Wilson Ornithological Society; Volume: 111; Issue: 2 Linguagem: Inglês
ISSN
1938-5447
Autores Tópico(s)Bat Biology and Ecology Studies
ResumoThe first detailed information on the vocalizations (including the first sound spectrograms) and natural history of the Caura Antbird (Percnostolu caurensis) and the Yapacana Antbird (Myrmeciza disjuncta) are presented. The Caura Antbird was studied in the Serrania de la Cerbatana, edo. Bolivar, Venezuela, where it inhabits humid foothill forest dominated by large rocks. Caura Antbirds specialized in foraging on or beneath rocks, a behavior unusual among the Thamnophilidae. The Yapacana Antbird was studied at a site along the south bank of the Rio Ventuari, edo. Amazonas, Venezuela. These antbirds were locally abundant in a specialized stunted woodland that grows on white sand soils. Based on newly described vocal characters, the closest relatives of P. caurensis appear to be P. leucostigma and P. schistacea, whereas M. disjuncta has no apparent close relatives and probably merits placement in a monotypic genus. Received 9 July 1998, accepted 5 Jan. 1999. Among the least known members of the large antbird family Thamnophilidae are the Caura Antbird (Percnostola caurensis) and the Yapacana Antbird (Myrmeciza disjuncta). Both species are nearly endemic to southwestern Venezuela and have remained relatively unobserved by modem field omithologists. The most extensive collections of both species (36 specimens of P. caurensis and 5 specimens of M. disjuncta) reside in the Colecion Omitol6gia Phelps (COP), Caracas, Venezuela. Single specimens of each species collected near Pica Neblina (edo. Amazonas, Venezuela) in 1984 by Field Museum of Natural History (FMNH) personnel represent the only specimens of P. caurensis and M. disjuncta collected anywhere since 1972 and 198 1 respectively. There is essentially no published information on habitat or behavior of the two species, and nothing is known of their vocalizations (Ridgely and Tudor 1994). In February 1998 I observed the habitats and behaviors and tape-recorded the vocalizations of Caura Antbirds in the Serrania de la Cerbatana, edo. Bolivar, Venezuela, and of Yapacana Antbirds in Yapacana National Park, edo. Amazonas, Venezuela. This is the first detailed information on the natural history and vocalizations of these species and allows a more informed assessment of their possible generic affinities. ’ Los Angeles County Museum of Natural History, 900 Exposition Blvd., Los Angeles, CA 90007. ZCorrespondence address: 1665 Garcia Rd., Atascadero, CA 93422; E-mail: kjzsrz@tcsn.net STUDY AREAS AND METHODS I observed Caura Antbirds lo-15 February, 1998 in the Serrania de la Cerbatana near Hato Las Nieves (6” 34’ N, 66” 12’ W), edo. Bolivar, Venezuela (Fig. 1). The Serrania de la Cerbatana rings a large valley vegetated mostly by a mixture of savanna and tropical dry forest, transected by narrow bands of gallery forest along occasional streams, and dotted with groves of Mauritiu palms in poorly drained areas. Three main rivers, CaAo Las Nieves, Rio Agua Fria, and Rio Danta, drain the valley. The Serrania mountain range rises dramatically from the valley, and on the southern and western borders is covered with humid forest. The south facing slopes of the mountains to the north of the valley are noticeably drier. The tallest peak in the chain is Pica Las Nieves at 2080 m. I studied Caura Antbirds along a 1.5 km trail that began in humid forest at 280 m elevation and extended up the side of a ridge to 400 m. I studied Yapacana Antbirds 22-27 February 1998 along a trail (hereafter the “Picua Trail”) near the settlement of Picua (4” 5’ N, 66” 45’ W) in Yapacana National Park, edo. Amazonas, Venezuela (Fig. 1). Picua is a small settlement of Piaroa and Mako Indians, on the south (left) bank of the Rio Ventuari at about 150 m elevation. The surrounding area contains a mosaic of different soil types that support a patchwork of distinct vegetation types. The Ventuari and its many small tributaries are flanked by bands (of varying width) of tall forest (15-25 m) that grow on yellow clay soils and are seasonally flooded. This varzea forest is characterized by a closed canopy with a fairly open understory and an abundance of vines and lianas. On higher banks above the river the v&rzea grades into a taller transitional forest with a denser understory. Much of the area farther removed from the river is dominated by white sand soils on which grow lower stature woodlands and grassy savannas. The savannas range in size from less than 1 ha to about 1 km*, with scattered shrubs and small trees. Larger savannas in the area contained stands of Mauritia palms. Large, isolated patches of red clay soils support tall (>30 m),
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