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 catastrophic rate that rapid and continuing population declines are suspected.
The population size is preliminarily estimated to fall into the band 10,000-19,999 mature individuals. This equates to 15,000-29,999 individuals in total, rounded here to 15,000-30,000 individuals.
Rates of forest loss in the Sundaic lowlands have been very rapid owing to logging, the spread of agriculture and forest fires. As a result, this specialist of lowland forest is suspected to be declining rapidly.
Caprimulgus concretus occurs on Sumatra, Belitung Island and Kalimantan (Borneo), Indonesia, Brunei, and Sabah and Sarawak (Borneo), Malaysia, where it is locally common, but rarely recorded (BirdLife International 2001). Most recent observations are from South Sumatra (e.g. Way Kambas National Park), East Borneo (e.g. Danum Valley) and South Sarawak (Kubah National Park) (D. Yong in litt. 2012, 2016). it has also been recorded recently near the Barito river in Central Kalimantan (N. Brickle in litt. 2012). This patchiness of distribution at least partly reflects the ease with which it is overlooked, but it does appear genuinely rare at many localities.
It is restricted to lower elevations (one record from 900 m, but usually below 500 m) where it frequents forest, perhaps particularly clearings and edges, heath forest and secondary growth. The true nature of its habitat use is uncertain, although it has been observed foraging from a perch inside forest. Breeding season is potentially from March-May (N. Cleere in litt. 2016).
If this bird is an extreme lowland forest specialist, as appears possible, then it must be in steep decline from habitat loss. Rates of forest loss in the Sundaic lowlands have been extremely rapid (Kalimantan lost nearly 25% of its evergreen forest during 1985-1997, and Sumatra lost almost 30% of its 1985 cover), because of a variety of factors, including the escalation of logging and land conversion, with deliberate targeting of all remaining stands of valuable timber including those inside protected areas. Furthermore, the major fires of 1997-1998 affected c.50,000 km2 of forest on Sumatra and Borneo, damaged at least 17 of Indonesia's parks and reserves and, following previous major conflagrations in 1972 and 1982-1983, accelerated the desiccation of the forest environment that renders regrowth and unburnt adjacent areas more vulnerable to fire and poorer in biodiversity.
Conservation Actions Underway
The species occurs at Way Kambas National Park, Sumatra, Gunung Niut Nature Reserve, Kalimantan and the Danum Valley Conservation Area (Sabah). Further research is likely to reveal its presence at other lowland protected areas in the future.
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
Bird, J., Westrip, J., Benstead, P., Allinson, T, Tobias, J., Taylor, J.
Yong, D., Yong, D., Brickle, N., Cleere, N., Bishop, K., Davison, G.
BirdLife International (2023) Species factsheet: Caprimulgus concretus. Downloaded from http://datazone.birdlife.org/species/factsheet/bonapartes-nightjar-caprimulgus-concretus on 28/11/2023.
Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 28/11/2023.