Bioacoustics of Scytalopus opacus

Distribution and habitat. S. o. androstictus inhabits the East Andes south of the Río Zamora in southern Ecuador , and the Andes of northernmost Peru north of the Río Marañón, on the eastern flank of the Huancabamba valley. It occurs in treeline scrub at elevations ranging from 3000 to 3650 m , locally down to 2600 m along exposed ridges. On the eastern slopes it is replaced below and in taller and more bamboodominated vegetation by S. parkeri Krabbe & Schulenberg and also meets the (as yet unnamed) eastern form of S. latrans Hellmayr , which locally ascends the slopes through disturbed humid forest. On the western slopes it is replaced below in drier, more open scrub by S. latrans subcinereus Zimmer. Vocalizations. The distinctive calls of S. o. androstictus are described above and shown in Fig. 3 . In spite of this taxon’s long genetic isolation and markedly different call, its song does not differ appreciably from that of S. o. opacus ( Table 3 ; Figs. 1–2 ), except by lacking the 1–3 churring introductory notes found in 16 of 21 recordings of opacus ( Fig. 5 ) and by sometimes being delivered without pause for two minutes or more, much longer than any recorded song of S. o. opacus . Usually, however, the song is 4–12 s long, as in nominate S. opacus . When S. o. androstictus in rare cases gives an introductory note, i.e. pauses after the first note, the note is of the same pitch and quality as the following notes. In vocalizations of both forms of S. opacus as well as in S. canus , the second, occasionally the first harmonic is loudest, and several more harmonics are often audible.