Black-bellied Malkohas (Phaenicophaeus diardi diardi) are very approachable in the field and I watched this one forage in thick foliage.
While hunting for prey it uttered a low frequency (2-3 kHz) single call, repeated every 1-3 seconds; I counted 36 per hour.
There was a soft response call in the distance and after a short while the partner turned up later to forage together. I suspect these are the common calls, used as contact calls while foraging.
This is one of a pair foraging nearby and keeping in contact with the calls I mentioned above.
Above shows the sonogram and waveform of the calls. A call recording can be heard here: https://www.xeno-canto.org/607155
Amar-Singh HSS (Dato’ Dr) – Ipoh, Perak, Malaysia
Location: Ipoh, Perak, Malaysia
Habitat: Broken primary forest with secondary growth
Date: 23rd November 2020
Equipment: Equipment: Nikon D500 SLR with Nikon AF-S Nikkor 500mm f/5.6E PF ED VR, handheld with Rode VideoMic Pro Plus Shotgun Microphone