Justification of Red List Category
This rather diminutive crow has a very small population, which is subject to a continuing decline in the face of rampant deforestation on its island home. It thus qualifies as Endangered.
The population is estimated to number 1,000-2,499 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 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
This species is suspected to be declining at a moderate rate, through forest loss (and perhaps also brood parasitism by cuckoos).
Corvus florensis is endemic to the islands of Flores and Rinca (C. Trainor in litt. 2007), Nusa Tenggara, Indonesia, where it is known chiefly from the lowlands in the western half of Flores (BirdLife International 2001). It seems likely that it has always been relatively uncommon, although locally frequent in undisturbed habitat. Overall, it is acknowledged to occur only at low densities, with most encounters involving single birds, and appears to have declined.
It inhabits semi-evergreen forest and degraded, moist, deciduous monsoon-forest (especially along watercourses) from sea-level to 950 m, where it generally frequents the canopy or subcanopy; although surveys in 2011 predominantly found it in mature forest (Reeve and Rabenak 2016). In coastal areas it occurs in open bamboo and open monsoon woodland or scrub which constitutes very dry, lightly wooded terrain. It has been recorded in degraded forest (Reeve and Rabenak 2016), and it will feed at the forest edge and in adjacent vegetable cultivation, but its general absence from small, relict forest patches suggests it may not adapt well to habitat fragmentation.
The primary threat is further habitat loss and fragmentation, driven principally by small-scale agricultural encroachment, which is already extensive on Flores, and has presumably resulted in a substantial decline in numbers and contraction of the species's range. Although it appears fairly tolerant of forest degradation, and of drier formations, it is basically forest-dependent. The large tract of lowland moist deciduous forest at Golo Bilas (one of two sites where the species is described as frequent) is also being cleared for firewood and construction materials. An additional minor threat may be posed by cuckoo parasitism, as the species is a host for Asian Koels Eudynamys scolopacea, and probably much less frequently for Channel-billed Cuckoos Scythrops novaehollandiae.
Conservation Actions Underway
Two recent surveys have been conducted on Flores, with C. florensis being a species targeted for study. It has been recorded in the Wolo Tadho Strict Nature Reserve and Wae Wuul Nature Reserve.
40 cm. Medium-sized, forest-dwelling crow. Plumage all black, dark iris. Feathering extends halfway along ridge of bill. Similar spp. Large-billed Crow C. macrorhynchos is much larger with more massive bill. Voice High-pitched, downwardly inflected cwaaa or cawaraa. Also waak repeated 1-3 times, resonant popping or gurgling and wheezing contact call.
Text account compilers
Taylor, J., Tobias, J., Davidson, P., Benstead, P., Westrip, J., Bird, J.
Pilgrim, J., Lehmberg, T., Trainor, C., Butchart, S.
BirdLife International (2017) Species factsheet: Corvus florensis. Downloaded from http://www.birdlife.org on 25/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/11/2017.