Archived 2018 topic: Coral-billed Ground-cuckoo (Carpococcyx renauldi): revise global status?

Coral-billed Ground-cuckoo is restricted to Thailand, Laos, Vietnam and Cambodia, where it inhabits lowland forest, scrub and second growth, to 900 m and exceptionally 1,500 m (Payne and de Juana 2018).

It is currently classified as Least Concern on the basis that it is not thought to approach the thresholds for listing in a threatened category under any of the Red List Criteria. However, sightings are seldom reported from anywhere outside of Khao Yai National Park (Thailand), and although its secretive ground-dwelling lifestyle makes it difficult to find and it may be under-recorded, it appears increasingly likely that it is genuinely very rare and decreasing. In particular, the potential threat from hunters using cable-snaring means that, although data are lacking, the species may well now qualify for a threatened category (J. W. Duckworth, S. Mahood and R. J. Timmins in litt. 2016, 2017, 2018).

It is extremely patchily distributed in northern Cambodia, based on the distribution of semi-evergreen forest (S. Mahood in litt. 2016). Snaring is not currently thought to be a major issue here but the total population must nevertheless be very small. In the south of the country in the Cardamom Mountains the status is uncertain. The amount of habitat remains large and must have held a large population of the ground-cuckoo, but snaring of animals such as civets and porcupines has apparently increased and may well now be affecting the species (S. Mahood in litt. 2016).

Its status in Laos and Vietnam is now thought to be very poor due to the impacts of industrial drift-fence cable snaring which has been in widespread use since the 1990s, and it has been suggested that rates of decline over the past three generations in those countries may have exceeded 80% (J. W. Duckworth in litt. 2016, 2018).

In Thailand the species continues to be regularly recorded within Khao Yai NP in the south of the country, but recent records from elsewhere in the country seem to be extremely sparse. The extent of cable-snaring in the country is unclear.

In addition to the threat from snaring, the species may also have been affected by the reduction in large mammal and primate populations, as it apparently forages in areas disturbed by these animals (S. Mahood in litt. 2016).


Assessment against Red List Criteria

Criterion A – It is extremely difficult to ascertain the likely population trend given the lack of data on the species and the uncertainty over the proportion of the population within the different range states. Although the impact of snaring in Laos and Vietnam may have driven declines of over 80% in three generations (13 years) in these countries, it is assumed that the rate of decline in Thailand is much lower, while the situation in Cambodia is unclear. It is possible that the overall rate of decline might lie within the range 30-49% in three generations (13 years), in which case the species would warrant listing as Vulnerable under criterion A2cd+3cd+4cd. If available evidence suggested the overall rate of decline could be as high as 50-79% in 13 years it would warrant listing as Endangered under the same criterion.

Criterion B – The species has an extent of occurrence (EOO) of 816,000 km2 as measured according to IUCN guidelines. Please note that this is the area of a minimum convex polygon around the known range, and does not equate to the extent of suitable habitat for the species. It therefore does not meet the threshold for listing as Vulnerable under criterion B1. The global area of occupancy (AOO) has not been calculated, but given the EOO, the AOO likely exceeds the threshold for Vulnerable under this criterion (2,000km2). Therefore, the species likely does not warrant listing as globally threatened under this criterion.

Criterion C – the global population size has not been estimated but it is possible that it is now approaches the thresholds for listing under this criterion.

It would warrant listing as Endangered under criterion C2a(i) if the total global population is estimated to number <2,500 mature individuals with ≤250 in each subpopulation, and an inferred continuing population decline.

It would warrant listing as Vulnerable under the same criterion if total population was <10,000 mature individuals with ≤1,000 in each subpopulation, and an inferred continuing population decline (or if the total population was <2,500 mature individuals with 250-1,000 in the largest subpopulation).

Criterion D – The range is too large, and the population is assumed to still be too large, to warrant listing this species as Vulnerable under this criterion.

Criterion E – To the best of our knowledge, no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.

Therefore, in the absence of any further information Coral-billed Ground-cuckoo may warrant listing as globally Vulnerable or Endangered under criterion A2+3+4 and.or criterion C2a(i), depending on best estimates of the global population trend over a 13 year period, and its likely overall population size and subpopulation structure. Comments and further information on the potential population size and trend are welcomed.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the information that is sought, or about the species’ Red List status.


Payne, R. & de Juana, E. (2018). Coral-billed Ground-cuckoo (Carpococcyx renauldi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 14 February 2018).

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5 Responses to Archived 2018 topic: Coral-billed Ground-cuckoo (Carpococcyx renauldi): revise global status?

  1. Thomas Gray says:

    The Cardamom Rainforest Landscape, SW Cambodia supports the largest extent of available habitat for coral-billed ground cuckoo in Cambodia.

    Recently much of this landscape <600-m has been camera-trapped (see summary focusing on mammals in Gray et al. 2017 Status and conservation significance of ground-dwelling mammals in the Cardamom Rainforest Landscape, southwestern Cambodia. Cambodian Journal of Natural History 2017 (1) 38-48) with no detection of this species. Almost all other comparably sized terrestrial species present in the landscape (including pheasants, peafowl, partridges, pittas, Malayan night heron, whistling and orange-headed thrushes) have been detected multiple times in this camera-trap data-set.

    IF <600-m represents high quality habitat for the species AND there is no evidence that detectability is lower than other birds from camera-traps THEN it seems likely that coral-billed ground cuckoo is extremely rare in this landscape.

    As such (caveats above not-withstanding) it appears likely that the species has suffered a significant decline perhaps meeting the Vulnerable criteria at least within the Cardamoms. Snaring is super-extensive throughout the Cardamoms (see e.g. Gray et al 2017 The wildlife snaring crisis: an insidious and pervasive threat to biodiversity in Southeast Asia. Biod. Cons. 27:1031-1037) and whilst civet snares are set in a way in which capture of ground-cuckoo is unlikely many of the snares set for ungulates would likely catch ground-cuckoo. And snaring levels might be sufficient to cause significant declines of a low density, wide-ranging species such as a ground-cuckoo.

    Snaring is probably a little less at higher elevations (particularly in the more remote Central Cardamoms) and the only recent records of the species in the landscape seem to be (heard) during bird tour visits to Aural Mountain. Therefore larger populations may remain in the more mountainous areas of the Cardamoms.

    I have more limited evidence from elsewhere in the species' range but no records from Cambodia's Eastern Plains where there is some suitable evergreen forest and there has been extremely intensive camera-trapping. I almost not aware of recent camera-trap records from Vietnam or Laos (certainly in projects I have been involved in) suggesting (again) either very low detectability from camera-traps or genuine rarity.

    Given this evidence of rarity across Indochina – which is presumably due to snaring and not genuine natural scarcity – then declines triggering Vulnerable seem reasonable and would the population size criteria.

  2. Simon Mahood says:

    Regarding status in the rest of Cambodia, there are a few recent records from semi-evergreen forest patches such as Phnom Kulen NP and nearby Community Forests, as well as suitable habitat within Preah Vihear Province. However, semi-evergreen forest is targeted for logging and clearance for agriculture (better soil) so I would agree with Tom that Vulnerable is a more appropriate status (although it would be good to have better data).

  3. Yong Ding Li says:

    The species show regularly at well-visited Khao Yai NP, and survey records show it to occur widely across the protected areas of the wider Khao Yai-Dong Phayayen Forest Complex. In Laos, there are few recent records (although some from the south may have escaped notice) However, I fully agree with the concerns of Simon and Tom with regards to its situation in Cambodia, where deforestation (and possibly incidental snaring?) could be a major issue. Vulnerable seems to reflect the situation across its broader range.

  4. Rob Martin (BirdLife International) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2018 Red List would be to list this species as Vulnerable under criteria A2cd+3cd+4cd.

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  5. J. W. Duckworth says:

    Maybe VU is inappropriate. In Lao and Vietnam, the wide spread of camera-trapping in the last decade has found this species at few localities and, mostly, only rarely. One camera-trap survey stands out as anomalous – in the middle Nam Ngiap catchment in about 2015 Coral-billed Ground Cuckoo was camera-trapped at a high proportion of camera-trap stations, commonly at some. Habitat nor style of camera-trapping there are not anomalous in any obvious way from many other camera-trapped areas in Lao. This suggests therefore that where it remains common, Coral-billed Ground Cuckoo is readily camera-trapped and that low camera-trap encounter rates in other areas are typically a faithful indication of poor local status. But the middle Nam Ngiap had not by then (for a variety of reasons) received any industrial snaring; a host of ground-dwelling snare-sensitive species also had high camera-trap encounter rates. Coral-billed Ground Cuckoo is, when present, easily found by call during a few months of the year; extensive surveys across Lao in the 1990s found it widespread and locally abundant. The camera-trapping in the last 10 years overlapped well with what we know from the 1990s is apparently suitable habitat for the species, although rarely if ever was in the same spots as the 1990s direct-observation surveys. It is a reasonable inference that the Lao population has collapsed since the 1990s, driven by the rapid expansion of industrial snaring. The assessment window under A2 is 13 years: 2005-2018. Much of the population loss in Lao since the early/mid 1990s had probably already occurred by 2005, but many big tracts of suitable habitat remained to be heavily snared; it is also likely that the rate of loss rose considerably between the late-1990s and the late 2000s. A Lao-specific categorisation of CR under A2 (and also, given likely future trends, under A3 and A4 – see my comments under Crested Argus) would be plausible. Population trend in VN over the last 13 years probably echoed that in Lao – there is also good overall picture of camera-trap prevalence for this species there, based on tracking of camera-trap results by the Saola Working Group, among others. In Cambodia, now, the information and opinion of the previous commentators indicates a low population and while the 2005 population is difficult to determine, if the species has not declined much in Cambodia since then, the proportion of the global population in Cambodia would be too low in 2005 to have much bearing on the global trend; and if it had been widespread and common in 2005 then losses in Cambodia would be broadly consistent with Lao and VN in terms of their effects on applying Red List categories and criteria. Thailand I find harder to build in. There isn’t any evidence given in other commentators’ replies above that the species is widespread and widely common there, but for people not familiar with its call, it is easily overlooked; I have no idea of the proportion of suitable CbGC habitat in Thailand that has been visited by people familiar with this species’s call, and in the calling season. It is vital to understand the proportion of the global population in Thailand in 2005 (for application of A2) and now (for A3) because so far as I am aware – and I stand at risk of correction from people with a clearer knowledge of Thailand than mine – industrial snaring in most of Thailand has not yet reached anywhere near the epidemic proportions in Lao and Vietnam, so snaring-driven declines in Thailand may be much less serious than in Lao and Vietnam, and while there will have been enormous habitat-loss-driven declines in Thailand, these took place very largely prior to 2005 so have no bearing on the current Red List category. If the proportion of the global population in Thailand in 2005 was about a quarter, and one assumes relative population stability there since versus 80% loss in Lao, Vietnam and Cambodia (i.e. at starting point 75% of the global population), this would imply (if I’ve done the maths right) a global average population loss of 60% in the last gens – solid EN territory. In the absence of any solid data on actual population change since 2005, categorisation of this species under A2 is going to have to take an approach of what the data would show did they exist (as indeed is always the case with A3, future declines, and in fact for the vast majority of tropical species even under A2). Unless Thailand was supporting a much higher proportion of global population in 2005 than I’ve guessed above, VU probably underportrays the global population loss of this species since 2005. Concerning the assignment of relative stability in Thailand since 2005 in the assumed near-absence of industrial snaring – during surveys in Lao in the early-mid 1990s, in areas not yet industrially snared, this species remained common, even in some rather fragmented habitat, despite decades of heavy ‘ordinary’ hunting. It seems peculiarly sensitive to industrial snaring.

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