Voice
A whistled series of accelerating calls falling in pitch and volume 'pwee pwee pwee pee-pee-pee-pee' or 'tee-tee-tee-tee-tita-tita-tita-tita-tee', a mournful, speeding and rising 'tay-ta-tee tay-ta-tee' and a harsh screeching 'tchree-tchree'.
Plaintive Cuckoo (Cacomantis merulinus) [XC815834]
by Lim Ying Hien from Stapok area of Batu Kawa, Bahagian Kuching, Sarawak, Malaysia (song)
Plaintive Cuckoo (Cacomantis merulinus) [XC655610]
by Bram Piot from Bestari Jaya, Selangor, Malaysia (song)
Nest
None. Egg(s) laid in that of the foster parents. The most common species are cisticolas, prinias and tailorbirds.
Subspecies
Grey-bellied form passerinus sometimes recognized as a distinct species on basis of reported sympatry in north-eastern India, but songs of passerinus and merulinus are the same, their juvenile plumages are similar, and the host species of passerinus appear to be the same as for subspecies querulus and merulinus, indicating a similar ecological role too. Situation unclear in eastern Nepal, where subspecies querulus was reported twice in 1980's, during Feb.
The following 5 subspecies are recognised:
passerinus (Scopoli, 1786) - India and Pakistan. Winters to Sri Lanka. Considered by some authors to be a distinct species, Grey-bellied Cuckoo (Cacomantis passerinus).
querulus Heine, 1863 - Assam and Lower Bengal east to southern China (including Hainan), and south through Myanmar, Thailand, Laos and Vietnam to northern Peninsular Malaysia; some migrate south to peninsular India and south-eastern Asia.
threnodes Cabanis & Heine, 1863 - Southern Peninsular Malaysia, Sumatra and Borneo.
lanceolatus (Müller, S, 1843) - Java and Sulawesi.
BirdLife International Species Factsheet