I often hear the advertising calls of the Greater Coucal (Centropus sinensis bubutus) in the early mornings 7-9am and occasionally duets (responsive calls) with a partner. Some details/comments about their calls.
The above image shows the posture of birds when they are making the calls. They usually lean a little forward with the head slightly bent and the neck/throat feathers quite distended. The beak is closed during calls. Occasionally I see them pointing the beak skywards (have an image).
The above sonogram/waveform has, what I consider, the more classical or common advertising calls that are made with no response from a partner but may have a distant response from a ‘rival’ male (presumed). The calls are made in a cluster of 6 notes (Well 1999 says 3-4 notes, but I suspect the first note is easy to miss unless you see it on a sonogram/waveform). These calls are spaced intermittently but often 6-7 seconds apart (sample of 10 calls: 12, 9, 14, 6, 7, 6, 7, 7, 9, 6 sec apart). A sonogram/waveform also shows that the calls are made in a crescendo – decrescendo scale. Wells (1999) describes the notes made as “bup”, while HBW 2018 terms them as “hoop”. Although the edited recording of the calls (see Sound Cloud link: https://soundcloud.com/amar-singh-hss/greater-coucal-centropus-sinensis-classical-calls) appears to be loud (directional mike used), in the field these are very low intensity calls as can be seen from the sonogram (sound frequency not exceeding 4 kHz).
The above is a sonogram/waveform of the less often heard duets or responsive calls with a partner. For this recording, both partners looked like mature adults, there was no physical contact and they were both high at the crown of a Rain Tree (Albizia saman) about 3-4 meters apart. The calls made are similar, low frequency calls but can go on for 10-12 seconds, comprise 15-30 notes and ‘rise and fall’ in volume. The two bird/partner’s calls can merge together (synchronise) as one at times (edited recording of the calls in Sound Cloud link: https://soundcloud.com/amar-singh-hss/greater-coucal-centropus-sinensis-mixed-or-responsive-calls).
The above is an image of the second bird calling, the partner.
Amar-Singh HSS (Dato’ Dr)
Ipoh, Perak, Malaysia
Location: Fringe of Ipoh City, Perak, Malaysia
Habitat: Semi-urban environment
Date: 12 &17th December 2018
Equipment: Nikon D500 SLR with Tamron SP 150-600mm f/5-6.3 Di VC USD, handheld, Rode VideoMic Pro