Olive Long-tailed Cuckoo Cercococcyx olivinus Scientific name definitions

Olive Long-tailed Cuckoo is very similar to sympatric Dusky Long-tailed Cuckoo and best separated by voice, but furthermore has slightly paler upperparts, narrower barring on the underparts, and less rufous on the undertail.

32–34 cm; 65 g. Adult dark olive-brown above , crown greyish, remiges and coverts often unbarred, tail long, rectrices broad, tipped white or pale rufous; wing about 82% of tail length; whitish below , with black barring; iris dark brown, eye-ring and skin around eye greenish yellow, bill slate, lower mandible greenish with slate tip, mouth yellow, feet yellow. Juvenile tawny with rufous feather tips above, throat pale, streaked below, rectrices pointed.

Sierra Leone (Gola Forest) and S Guinea to S Ghana, then intermittently E through S Nigeria, Cameroon, N Congo and N DRCongo to W Uganda; also in the Kasai zone (NE Angola, SW DRCongo) (1 Dean, W. R. J. (2000). The Birds of Angola. An Annotated Checklist. B.O.U. Check-list 18. British Ornithologists’ Union, Tring, UK. Close ) and S Congo (Mayombe); NW Angola; NW Zambia.

Forest , mainly unbroken mature forest, also small patches of forest, secondary growth, and gallery forest.

Insects, mainly hairy caterpillars . Forages in middle and upper strata of forest and in crowns of trees; accompanies mixed-species flocks of foraging birds.

Vocal Development

No information. There are no observations of fledglings being fed by host parents, and thus begging call has not been described. At the start of the next breeding cycle, all birds sing the stereotypic adult song (without having been in close contact with their biological parents).

Vocal Array

Like many other Old World cuckoo species, Olive Long-tailed Cuckoo has 2 main vocalizations: a short phrase repeated incessantly (Song) and a long note series typically only uttered once (Long call). Both vocalizations are very stereotypical.

Song. A short phrase of three whistled notes that is repeated many times at a rate of 3‒4 phrases/10s wip-tew-tyew....wip-tew-tyew...... First note is shortest, next two are louder and downslurred, and frequency typically between 1.5 and 2.2kHz. Quite similar to Red-chested Cuckoo (Cuculus solitarius) but slower-paced.

Long call. A long series of drawn-out disyllabic notes toowoo...toowoo..toowoo.. Notes have a duration of 0.5‒0.7s, are rather flat-pitched between 1 and 2kHz, and are given at a pace of 1.0‒1.5notes/s. The series usually starts rather faint and gradually swells in amplitude becoming emphatic, going on for 15s or more.

Geographic Variation

Has not been studied in detail, but sound recordings indicate there is very little (if any) variation in both vocalizations over the wide range of this species. Even small disjunct populations in Angola and northwestern Zambia sing identically.

Phenology

Can be heard most of the year, but there are regional fluctuations, likely influenced by weather and breeding cycle of the host species, apparently more vocal during the early rains (2 Dowsett-Lemaire, F., and R. J. Dowsett (2014). The Birds of Ghana: An Atlas and Handbook. Tauraco Press, Liège, Belgium. Close ).

Daily Pattern of Vocalizing

Mainly vocal during early morning and late afternoon. During the height of the season, may sing intermittently for hours. Also sings at night (2 Dowsett-Lemaire, F., and R. J. Dowsett (2014). The Birds of Ghana: An Atlas and Handbook. Tauraco Press, Liège, Belgium. Close ).

Places of Vocalizing

Typically sings from high in the canopy, and is notoriously difficult to see (unless birds are lured in with playback). In Angola, said to prefer perches in the upper canopy, higher than sympatric Dusky Long-tailed Cuckoo (Cercococcyx mechowi) (3 Ripley, S. D. and G. H. Heinrich (1966). Additions to the avifauna of northern Angola II. Postilla 95:1–29. Close ).

Sex Differences

Little information. One could speculate that the Long call is a female vocalization (analogous to Cuculus cuckoos), but Song and Long call can be uttered by the same individual.

Social Context and Presumed Functions of Vocalizations

Little information. Song is far carrying and uttered for long periods. It likely plays a role in mate attraction and possibly also has a territorial function. Birds readily approach a playback source. Long call is often uttered in combination with Song.

None documented.

Not globally threatened. Population levels unknown, but species said to be uncommon in Nigeria. Like C. mechowi, however, this is a shy and secretive species, noticed only when calling in tops of tall forest trees.