Corvus florensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Corvidae

Scientific Name: Corvus florensis Büttikofer, 1894
Common Name(s):
English Flores Crow
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Endangered C2a(ii) ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Butchart, S., Pilgrim, J., Trainor, C. & Lehmberg, T.
Facilitator/Compiler(s): Benstead, P., Bird, J., Davidson, P., Taylor, J., Tobias, J., Westrip, J.
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.

Previously published Red List assessments:

Geographic Range [top]

Range Description: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.

Countries occurrence:
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:10900
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:6-10Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):950
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: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.

Trend Justification:  This species is suspected to be declining at a moderate rate, through forest loss (and perhaps also brood parasitism by cuckoos).
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:600-1700Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology: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.

Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):7.3
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: 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.

Conservation Actions Proposed
Conduct further surveys in central and eastern Flores (particularly in northern Ende, where moist, deciduous monsoon-forest is reported to be extensive) to establish its current distribution and population size. Conduct ecological research to assess its success in different forest-types and the impact of cuckoo parasitism. Extend Wolo Tadho Strict Nature Reserve and support the establishment of further protected areas in western Flores (including Tanjung Kerita Mese, Golo Bilas and Nanga Rawa).

Amended [top]

Amended reason: Edited Habitats and Ecology Information text. Added new reference, new Contributor and new Facilitator/Compiler.

Citation: BirdLife International. 2017. Corvus florensis (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22705956A110289015. . Downloaded on 16 August 2018.
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