- Cacomantis passerinus
18–22 cm (7-8½ in); Generally a small cuckoo with a long tail and a rather thin curved bill.
- Dark grey with blackish wings and tail
- White vent (sometimes also belly)
- White bars and spots on undertail
- Bright rufous above with some black chevrons on wings and mantle
- Rufous tail with no markings
- White below with fine black bars
- No supercilium (see Banded Bay Cuckoo)
- Duller than adults
- Undertail with black and pale bars
Non-hepatic females are rare. They are duller than males and browner.
Partially migratory. Himalayan birds move south, Indian birds are probably resident. Arrives in Sri Lanka in October and leaves again in April.
Sometimes considered conspecific with Plaintive Cuckoo Cacomantis merulinus. The song of both species is very similar, juveniles look the same and their host species are the same too. The split bases on reported sympatry in NE India.
Open woodland, secondary forest, scrubland, parkland, gardens, agricultural areas, towns and villages, also subtropical pine forest. Common in most of its range.
Their diet consists mostly of hairy caterpillars.
Breeds from June to September. Like many other cuckoos this species is a brood-parasitic.
Sings from treetops, frequently changing position and tree. Sings at night and in dim weather at day. Silent in winter.
Recording by Alok Tewari
Mangar Bani Forest, Faridabad-Gurgaon Road, Haryana, India, June-2018.
Calling in a soundscape that has calls of Purple Sunbird, Common Babbler, Common Hawk-cuckoo and Rufous Treepie in the BG.
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2017. The eBird/Clements checklist of birds of the world: v2017, with updates to August 2017. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
- Handbook of the Birds of the World Alive (retrieved July 2015)
- BirdForum Opus contributors. (2021) Grey-bellied Cuckoo. In: BirdForum, the forum for wild birds and birding. Retrieved 11 April 2021 from https://www.birdforum.net/wiki/Grey-bellied_Cuckoo