Justification of Red List category
This species has a large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). The species is considered to be stable and hence does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
The global population size has not been quantified, but the species is described as uncommon to rare (Eaton et al. 2021). However, an accurate assessment on the status of this species is hampered by its identification, particularly due to confusion with A. rhodogaster, but occasionally A. trinotata and Lophospiza griseiceps. Much of its range is also poorly known.
Given this species's occurrence in montane forests, encroachment by agriculture and timber extraction has been minimal in its range. Global Forest Watch (2021) data, using Hansen et al. (2013) methods and data disclosed therein, suggest that forest loss in its range has been minimal (0.2% per annum) and is not necessarily above the rate of natural flux. The population is therefore suspected to be stable, but may decline if forest loss begins to encroach on higher elevation forest.
Accipiter nanus is restricted to Sulawesi, Indonesia where recorded from North, Central, South, and South East Sulawesi provinces (White and Bruce 1986, Berryman and Eaton 2020, eBird 2021). It has been recorded from very few localities, although its similarity to the Vinous-breasted Sparrowhawk A. rhodogaster has possibly resulted in it being under-recorded. All confirmed records are from montane forest above 550 m, with lowland records (e.g. Martin et al. 2018) refuted (Eaton 2018, Eaton et al. 2021).
This is a species of montane and hill forest above 550 m (chiefly above 900 m), with no confirmed records from the lowlands (Ferguson-Lees and Christie 2001, Berryman and Eaton 2020, Eaton et al. 2021).
Forest at middle and higher elevations on Sulawesi is relatively intact at present. However, deforestation is having a major impact at lower elevations and these continue to encroach higher up. The drivers behind on-going deforestation are thought to be rural development and encroachment of settlements, agricultural expansion and logging pressure. As a species of montane areas, it is potentially at risk from the effects of projected climate change on the distribution and extent of its habitats.
Conservation Actions Underway
CITES Appendix II. Occurs in several protected areas.
23-28 cm. A small and compact sparrowhawk, whose plumage is confusingly similar to that of A. rhodogaster, with dark grey upperparts and peachy breast quickly fading to clean white on the belly. Similar spp. A. rhodogaster is very similar and adults are best told by voice or in the hand, where the obscure white outer tail spots of nanus can be seen. The underwing of A. rhodogaster is more strongly mottled on the wing linings and less strongly barred on flight feathers (Eaton et al. 2021).
Text account compilers
Mahood, S., Berryman, A., Martin, R.
BirdLife International (2023) Species factsheet: Accipiter nanus. Downloaded from http://datazone.birdlife.org/species/factsheet/dwarf-sparrowhawk-accipiter-nanus on 29/09/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 29/09/2023.