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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
FIG. 3. Contact calls of Willisornis populations. Nomenclature follows recommendations of this paper. Acronyms for 
recording archives in Appendix. (A) W. v. nigrigula, Jacareacanga, Para, Brazil (ISL BMW 219:065). (B) W. p. 
poecilinotus, Reserva Ducke, Amazonas, Brazil (ISL BMW 131:020). (C) W. p. griseiventris, Prainha Nova, Amazonas, 
Brazil (ISL BMW 196:028). (D) W. p. griseiventris, Explorer’s Inn; Madre de Dios, Peru (ML 35547). (E) W. p. duidae, 
Parque Nacional Natural Chiribiquete, Caqueta, Colombia (ISL MAR 006:033). 
differences were found with regard to elevational 
differences within lepidonotus , even though a 
small sample of higher elevation loudsongs 
tended to be higher pitched and faster. 
Initial notes of griseiventris loudsongs in 
general were lower-pitched than the equivalent 
lepidonotus notes, but loudsongs of the western¬ 
most population of griseiventris , nearest the range 
of lepidonotus , were highest in frequency and 
closest to notes of lepidonotus , suggesting clin- 
ality. We identified no differences in griseiventris 
loudsongs east and west of the Rio Madeira. 
Contact Call. —These calls consist of abrupt 
notes given when flying between perches as well 
as when perched. They differed diagnosably 
between what we termed a twitter, which is found 
only in the repertoires of nigrigula/vidua, and a 
psit, which is delivered only by the remaining 
populations (Fig. 3). The twitter is a short (2-16, 
typically 3-5), high-pitched series of clear, almost 
tinkling, musical notes (Fig. 3A) Each note bends 
slightly downward in frequency; the series 
descends slightly in frequency; and intervals 
between notes with rare exceptions lengthen 
slightly (typically from 60 to 75 millisec, ex¬ 
tremes 34 and 112 millisec). Notes, especially the 
initial note, often start with a small hook 
(Fig. 3A). In contrast, the psit note was shaped 
like an inverted U or V, usually sounding lower- 
pitched and harsher to the human ear than the 
twitter. The psit was typically given singly 
(Fig. 3B and C), but occasionally in short series 
that usually decreased in frequency, sometimes 
dramatically so (Fig. 3D and E). 
The duration of the psit call varied among 
populations. The mean length in northern lowland 
populations (poecilinotus , duidae , and lowland 
lepidonotus) was 0.093 sec (range = 0.071-0.118, 
SD = 0.0120, n = 20; Fig. 3B), whereas the mean 
for highland and southern populations (highland 
lepidonotus and griseiventris) was 0.054 sec (range 
= 0.047-0.063, SD = 0.0051, n = 20; Fig. 3C). 
The difference was diagnosable under our criteria. 
However, when four examples for gutturalis were 
added to the highland and southern populations, the 
mean and variance were slightly larger 0.055 sec 
(range = 0.047-0.069, SD = 0.0066, n = 24), 
narrowly failing our statistical test. 
Chirrs. This call consisted of a short series 
(duration: x = 0.596 ±0.189 sec, range = 0.248- 
1.020 sec, n = 52) of abrupt (5—9 millisec) notes, 
vertical on a spectrogram, repeated rapidly (~5 
