BIOMETRY OF TWO SYMPATRIC SPECIES OF THE GENUS HYPOCNEMIS (AVES: THAMNO- PHILIDAE) IN SOUTHWESTERN AMAZONIA

Abstract

Differences in size and shape between sympatric congener species may affect their dominance interactions. In Amazonia, the Pe- ruvian Warbling-Antbird (Hypocnemis peruviana) is partly sympatric with the Yellow-breasted Warbling-Antbird (Hypocnemis subflava). Here, we investigated whether biometric differences exist between H. peruviana and H. subflava, and whether the species are sexually dimorphic. We measured 10 biometric traits in 52 individuals (24 H. peruviana and 28 H. subflava). From the analyses, we conclude that H. peruviana is slightly larger than H. subflava and that this may reflect a certain competitive dominance of the former over the latter. Some biometric traits were also different between the sexes in both species, which may minimize the competition for resources between the sexes.