Isler and Whitney • SPECIES LIMITS IN AN ANTBIRD COMPLEX 
7 
Time (sec) 
FIG. 4. Chirr and raspy calls of Willisornis populations. Nomenclature follows recommendations of this paper. 
Acronyms for recording archives in Appendix. (A) Chirr W. p. griseiventris, Humaita, Amazonas, Brazil (ISL BMW 
219:081). (B) Raspy call W. p. poecilinotus , Iwokrama Forest Reserve; Guyana (ISL BMW 158:003). (C) Raspy call W. p. 
griseiventris, right bank Rio Jiparana opposite Palmeiras, Rondonia, Brazil (ISL BMW 208:020). (D) Raspy call W. v. 
vidua, Caxiuana, Para, Brazil (ISL BMW 180:048). 
notes in 0.1 sec), and typically descending in pitch 
(e.g., apex of notes ~ 5 mHz descending to 
~4 mHz) (Fig. 4A). Chirrs have been recorded 
for all populations. No diagnostic differences in 
chirrs were found among Willisornis populations, 
although the duration of chins of nigrigula and 
vidua overlapped only slightly. Average chirr 
duration in nigrigula recordings was 0.728 ± 
0.209 sec, range = 0.420-1.020, n = 10), whereas 
that of vidua was 0.399 ± 0.053 sec, range = 
0.322-0.444, n = 6). Difference in means met 
student’s r-test at 99%. At times chirrs were 
combined with contact calls. 
Raspy Series. —Notes in raspy series were 
typically repeated 2-4 times but were sometimes 
given individually or in longer series. Typical 
poecilinotus calls had “U” shaped notes (Fig. 4B); 
the series descending slightly in pitch, sounding 
like “cheery, cheery, churry, churry.” The call of 
griseiventris typically had the initial part of the 
note truncated, making it look like a “J” in a 
spectrogram, and the base of the notes typically 
rose slightly in frequency (Fig. 4C). Few calls were 
available for duidae, lepidonotus, and gutturalis , 
but they suggested intermediacy between poecili¬ 
notus and griseiventris and, consequently, differ¬ 
ences among these five subspecies were not 
considered diagnostic. We suspect that analysis 
of larger samples may detect diagnostic differences 
in raspy series among these populations. Note 
shapes in raspy series of vidua and nigrigula, in 
contrast, differed consistently from those of other 
