Justification of Red List category
This species is classified as Endangered since it has a very small range and population size, occurring at only one location, an active volcano where clearance of forest for agriculture by the island's large and increasing human population is causing a continuing decline in the area of suitable habitat, and thus its extent of occurrence, area of occupancy, and population.
Surveys in 2018-2019 estimated that about 133 km2 of suitable habitat exists for this species, in forests between altitudes of 800 m and 2,000 m. The average population density was estimated to be c.27 individuals/km2, and the global population was estimated to be 3,452 total individuals (Ibouroi et al. 2019). This is roughly equivalent to 2,300 mature individuals.
This species's population is inferred to be declining due to ongoing habitat loss and degradation within its range. Data from Global Forest Watch (2020) suggests the species's range has experienced a rate of forest loss of 2% over the 10 years between 2009 and 2019. Similarly, Global Forest Watch data suggests that 0.54% of forest was lost between 2016-2019. If this rate is projected forward over 10 years, it equates to a suspected rate of decline of 1.8%. While habitat loss is considered the primary threat, this species is also threatened by competition from invasive species, and as such may be declining at a rate higher than just forest loss alone. The suspected rate of decline has therefore been placed in the band of 1-19% over ten years.
Otus pauliani is found only on Mt Karthala, an active volcano on Grand Comoro (= Ngazidja), in the Comoro Islands. Models by Ibouroi et al. (2019) estimate the extent of suitable habitat to be 133 km2.
This species has been reported from 650 m upwards to the tree line (Louette et al. 2008), although a more recent survey gave a lower limit of 800 m (Ibouroi et al. 2019). It is territorial, occurring in primary, montane, evergreen forest, favouring areas with old hollow trees, but is also found in "pioneer forest"; (forest that grows on rocky soils [Louette et al. 1988, 1990]) and regenerating forest dominated by Psidium cattleianum (Safford 2001), although it is not clear whether it occurs in similar densities in such degraded habitat. It shows a preference for edge habitat: either edges along the upper limits of the forest where it is replaced by giant heath Philippia, edges along old lava-flows, or edges of open areas within the forest itself (Louette et al. 1988). Its feeding and breeding ecology are unknown.
Since 1983 intact forest may have declined by over 25% as agriculture, on all but the poorest soils, has advanced steadily up the slopes of Mt Karthala toward the habitat of O. pauliani (Safford 2001). There is large clearance for road construction on the western side above Mvouni, relatively intensive logging for plank production using chainsaws in the south, above Kourani, and cattle grazing on the Phillipia heaths in the highlands (K. Green in litt. 2012). Secondary forest in the agricultural belt on the mountain is dominated by exotic plants, particularly strawberry guava Psidium cattleianum (Safford 2001), which could spread into and degrade remaining native forest. Commercial logging occurs in a 50 km2 concession on the south-western slopes (Safford 2001). Pioneer forest, although unsuitable for agriculture and of little value for logging, is susceptible to fire and may be burnt to provide grassland for cattle (Louette et al. 1990). Grazing is increasing - even at high altitudes - and could prohibit forest regeneration (Louette et al. 1988; Louette and Stevens 1992). Introduced rats and Common Myna Acridotheres tristis may act as competitors or nest predators (Safford 2001). If plans to build a road to Mt Karthala's crater are resurrected, exploitation and fragmentation of the forest, and the spread of exotic species, could be accelerated (Safford 2001). The most recent survey by Ibouroi et al. (2019) conclude that the main threats are habitat disturbance and conversion of natural forest into agricultural land.
Conservation Actions Underway
CITES Appendix II. A protected area (national park, biosphere reserve or resource management area) on Mt Karthala has been suggested, but has not yet materialised (Louette and Stevens 1992; Safford 2001). Protected area planning was underway for the Karthala forests in 2012 (K. Green in litt. 2012).
Conservation Actions Proposed
Restore forest and secure corridors in the Karthala remnant forest, avoid the conversion of secondary forest into agricultural land, use existing agroforestry for plantation development, and involve a broad community of local individuals and entities in their conservation and management (Ibouroi et al. 2019). Previous proposals included: research the ecology of this species to aid conservation plans. Create a protected area on Mt Karthala to encompass the remaining native forest, and develop a land-use strategy (Louette and Stevens 1992; Safford 2001). Encourage locally-organised ecotourism as an alternative source of income for inhabitants of the Mt Karthala area (Safford 2001). Develop an environmental education programme on the island (Louette and Stevens 1992).
20-22 cm. Small owl. Only one colour form: greyish-brown, heavily barred, streaked and vermiculated. Bright yellow eyes. Voice Whistled toot given at one-second intervals.
Text account compilers
Ashpole, J, Bird, J., Butchart, S., Doulton, H., Ekstrom, J., Green, K., Louette, M., Marsh, C., Pilgrim, J., Safford, R., Shutes, S., Symes, A., Warren, B. & Westrip, J.R.S.
BirdLife International (2023) Species factsheet: Otus pauliani. Downloaded from http://datazone.birdlife.org/species/factsheet/grand-comoro-scops-owl-otus-pauliani 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.