Data Zone
Justification of Red List category
This species qualifies as Vulnerable because it is restricted to low-lying forest in a region where this habitat-type is being cleared and degraded at such a rate that rapid and continuing population declines are suspected.
Population justification
On Sumatra, if it is truly confined to the eastern coastline (sensu Eaton et al. 2021), as seems likely, the population may be very small as little suitable habitat remains. Recent records come from only Way Kambas National Park (Olah and Simay 2007, eBird 2023) and the Kampar Peninsula (RER 2017) where there is unlikely to be enough suitable habitat to support more than 1,000 mature individuals. On Borneo, it is evidently rare (and much-depleted), although the area of suitable habitat in Kalimantan remains comparatively large (Mann 2008) and even if the species occurs at a low density as records suggest, the population probably numbers in the thousands. Precautionarily, a population size of 10,000-19,999 is suspected, but such a value represents little more than a best guess, and requires urgent survey attention.
Trend justification
Caprimulgus concretus is thought to be declining rapidly in response to extensive forest cover loss across its range. In the absence of population data, forest cover loss is used as a proxy to estimate the rate of reduction over the past three generations (11.1 years: 2012-2023), however doing this accurately relies on robust knowledge of the species' distribution when forest cover was more extensive. There is, however, much uncertainty on how widespread it was historically, and its precise habitat requirements (e.g. its persistence in plantations/degraded forest) remain poorly elucidated. Under a range of scenarios, forest cover loss in the species' mapped range is thought to have reduced by 20-41% over the last three generations (Global Forest Watch 2023, based on data from Hansen et al. [2013] and methods disclosed therein). Precautionarily, towards the upper limit of these losses (30-40%) is accepted here given the species' apparent confinement to specialised habitat. This rate of loss is also suspected to occur into the future, with comparatively little of the species' range circumscribed by protected areas (UNEP-WCMC and IUCN 2023), and most of it accessible for exploitation.
The species is endemic to Borneo and Sumatra. On Borneo, it occurs in Brunei Darussalam (see, e.g., Grafe et al. 2022), Malaysia and Indonesia. On Sumatra, Indonesia, it appears to now be highly localised, with almost all records from Way Kambas National Park and the Kampar Peninsula (RER 2017, eBird 2023). Its distribution in Sabah is difficult to determine: There are no records from Sabah, with those listed in Mann (2008) considered erroneous (Eaton et al. (2021).
The exact habitat requirements are improperly known. It appears to be confined to primary, secondary and heath forest below 500 m (Eaton et al. 2021), although very rarely it has been reported from plantations (RER 2017), but this at a site adjacent to pristine peatswamp, such that observations in plantations may refer to wandering/feeding individuals. A nest (the first ever documented) found in March 2022 in Brunei was in heath forest (kerangas) on the edge of a freshwater swamp (Grafe et al. 2022).
Forest destruction in the Sundaic lowlands of Indonesia and Malaysia has been extensive, for timber and conversion to agriculture. In particular the rapid expansion of oil palm has driven the conversion of the majority of remaining lowland forest in the region. Between 2011 and 2022, tree cover was reduced in its range by 19–41% (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein). Associated with the forest loss has been an increase in fire frequency, extent and severity, particularly during strong El Nino events (as in 1998).
Conservation Actions Underway
This species occurs in a handful of protected areas on Borneo, in all range states, however the majority (>80%) of suitable habitat remains unprotected (UNEP-WCMC and IUCN 2023). It occurs in the Kampar Peninsula, which is subject to protection and passive monitoring (see RER 2017).
21-22 cm. Medium-sized, cryptically patterned, forest-dwelling nightjar. Male has brown upperparts, spotted chestnut and lacking nuchal collar. Dark brown wings with feathering tipped and spotted chestnut and buff. Dark scapulars broadly fringed pale buff. White submoustachial stripe and throat. Brown underparts barred chestnut, becoming buff with brown bars on belly and flanks. White tips to outermost tail feathers. No white in wing. Female similar, but only rarely has any white in tail. Voice Strange, low, mournful wa-ouuu, the second note descending in pitch, given mainly at dawn, dusk and on moonlit nights.
Text account compilers
Berryman, A.
Contributors
Allinson, T, Benstead, P., Bird, J., Bishop, K.D., Brickle, N., Cleere, N., Davison, G., Taylor, J., Tobias, J., Westrip, J.R.S., Yong, D. & Yong, D.
Recommended citation
BirdLife International (2024) Species factsheet: Bonaparte's Nightjar Caprimulgus concretus. Downloaded from
https://datazone.birdlife.org/species/factsheet/bonapartes-nightjar-caprimulgus-concretus on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.