However, I employed moderate playback later, to improve my chances to take pictures. The bird on the photo (same individual as in figure 2 of main page) is responding to this playback.To top of page
(A) Sound given by a Bicoloured Hawk that flew over me, reacting to playback, at a distance of several hundred meters from the nest mentioned before. The variing amplitude of the vocalization, first increasing and then decreasing, probably reflects the changing distance between the flying bird and the microphone, and not real changes in the loudness of the song. The two notes in the highlighted area are shown in detail in (B).
(B) Details of highlighted area of (A). The song of Accipiter bicolor has a strange, squawking-like timbre. The physical correlate of this are the many pronounced harmonics over a wide frequency range, in this example from 600-800 Hz (fundamental) to over 14 kHz.
Spontaneous song given by a Bicoloured Hawk (very probably the individual in figure 1), when I approached its nesting site. The bird was apparently alone at the nest, and vocalized 3-4 times during the 15 mins or so that I stayed in the vicinity. Song h1759 was given while the hawk flew from one tree to another.
Sounds produced by a Bicoloured Hawk in response to playback. I was walking on a trail at a distance of 150-200 meters from the nesting site, which at this moment was still unknown to me. The hawk flew over me, apparantly looking for the presumed conspecific, and repeatedly gave these calls. The sonogram shows the first two (labels c1 and c2) of the four notes in recording h1698. I suppose that these vocalizations, which I also heard on several occasions, are contact calls.
In the background, Pachyramphus polychopterus, Tolmomyias flaviventris, Vireo olivaceus, and possibly Hemitriccus margaritaceiventer.