Justification of Red List category
This poorly known terrestrial forest bird is thought to have an extremely small and declining population, and as such it qualifies as Critically Endangered, although further information might warrant a reassessment of its status.
The population is estimated to number 50-249 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 75-374 individuals in total, rounded here to 70-400 individuals.
The population is suspected to be in decline owing to habitat loss and hunting pressure, although the likely rate of decline has not been estimated.
This species is endemic to the island of Sumatra, Indonesia, where it is only known from eight specimens and a recent series of sightings, the majority of which have come from the Barisan Mountains in the southern half of the island (BirdLife International 2001). Unrecorded since 1916, an individual was trapped and photographed in November 1997 at Bukit Barisan Selatan National Park (BBS) (at 500 m) (Zetra et al. 2002). Subsequent records comprise an unconfirmed sighting in 2000 in the Bukit Rimbang-Baling Wildlife Sanctuary from an area of hilly, open secondary forest with dense undergrowth at 700m (Zetra et al. 2002), a bird photographed by a camera-trap near Kerinci Seblat National Park in 2006 (Anon 2006, Dinata et al. 2008) and a bird caught and brought to conservationists in BBS in 2007 (N. Brickle in litt. 2007, 2008, 2010). Up to five birds have since been seen and heard in the wild near the site of the original trapped bird in BBS; at Way Titias, near Liwa, in central BBS, and another heard calling, and reported by hunters, in an area north of BBS (N. Brickle in litt. 2007, 2008, 2010). Very little is known about its population status. Its close relative, the Bornean Ground-cuckoo C. radiatus, is unobtrusive, which may partly account for the lack of records. However, it seems likely that it is rare and locally distributed.
Information noted on specimen labels reveals that it inhabits foothill and lower montane forest, with records from 300-1,400 m. All recent records are from 800-1,000 m (N. Brickle in litt. 2007, 2008, 2010). Brief habitat descriptions from collecting localities and the site of the recent sightings indicate that it occurs in primary or little-disturbed forest (Anon 2006). All known sites appear to have a relatively dense understorey. It is a ground-dweller, apparently feeding on invertebrates, reptiles and small mammals on the forest floor (based on the range of prey captured and eaten by a captive bird in a semi-wild enclosure) (N. Brickle in litt. 2007, 2008, 2010). Other than this, there is no information on its ecology and behaviour.
Deforestation has been extensive on Sumatra and this is probably the main threat. At least two-thirds to four-fifths of original lowland forest cover and at least one-third of montane forest have been lost, primarily to agricultural encroachment by shifting cultivators, which is currently affecting large areas of lower montane forest, even within protected areas. At the type locality, Gunung Singgalang, forest had been cleared up to 1,800-1,900 m as early as 1917. In addition, being a ground-forager, it is possibly susceptible to bycatch through hunting by use of snares: a recent record was obtained when a bird was captured by a hunter, almost certainly in a snare set for Red Junglefowl Gallus gallus (N. Brickle in litt. 2007, 2008, 2010).
Conservation Actions Underway
There are 20 protected areas in the Barisan Mountains, some of which lie within the current known range of this species. The recent records come from Bukit Barisan Selatan National Park and near Kerinci Seblat National Park. Also, one specimen was collected from within, or close to Kerinci Seblat National Park. Survey effort is likely to increase following the recent recording of its call: knowledge of ground-cuckoo calls has facilitated study of two other Asian species in the past. Efforts to protect habitat and promote tourism are being developed.
55 cm. Large, terrestrial, forest-dwelling cuckoo. Long, full tail. Sturdy green legs and bill. Black crown, shading to green on hind crown. Dull green mantle, upper back, neck sides, wing-coverts and secondaries. Brown lower back with broad greenish-brown bars. Glossy greenish-black wings and tail. Dull green lower throat and upper breast, rest of underparts cinnamon-buff, more rufous on flanks. Green, lilac and blue bare skin around eye. Voice Repeated low whistles (falling then rising in tone: WE-ow-WE), plus issued in a rising series (we-ow-we, we-ow-we, we-ow-we, we-ow-we; each phrase slightly higher than last).
Text account compilers
Benstead, P., Butchart, S., Bird, J., Symes, A., Taylor, J., Tobias, J.
Brickle, N., Bishop, K., Linkie, M.
BirdLife International (2023) Species factsheet: Carpococcyx viridis. Downloaded from http://datazone.birdlife.org/species/factsheet/sumatran-ground-cuckoo-carpococcyx-viridis on 23/09/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 23/09/2023.