Out of the darkness: the first comprehensive survey of the Critically Endangered Anjouan Scops OwlOtus capnodes

Abstract

SummaryAlthough birds are among the best studied taxa, many of the globally threatened species lack the information required to fully assess their conservation status and needs. One such species is the Anjouan Scops Owl Otus capnodes which was presumed extinct until its rediscovery to science in 1992. Based on the limited extent and decline of the moist forests in the highlands of Anjouan in the Comoro Islands, a population size of only 100–200 pairs was estimated and the species was classified as ‘Critically Endangered’. The current study is the first comprehensive survey ever conducted on this species, and aimed to establish the current distribution and population size. Point counts with distance sampling were conducted across the agroforestry and forest zones of Anjouan in both a dry and wet season. A niche suitability model predicted the species distribution to be wider than expected with owls observed as low as 300 m altitude and in highly modified agroforestry habitats. However, the encounter rate in natural relatively undisturbed forest was significantly greater than in other habitats. The wider than expected geographic range of O. capnodes supports a possible downlisting of this species on the IUCN Red List to ‘Endangered’. Population size was found to be far greater than previously thought, at approximately 3,450 individual owls in the dry season and 5,450 in the wet season. These results show the importance of investing in robust surveys of poorly known and cryptic bird species, and provide up to date and important information for landscape scale conservation planning in the Comoros Islands.

The recently discovered Principe Scops-owl is highly threatened: distribution, habitat associations, and population estimates

“…1972), which has been shown for other insular owl populations, such as the Anjouan Scops-owl, Otus capnodes (Gurney, 1889), with 55–87 individuals/km 2 (Green et al . 2014), and the Grand Comoro Scops-owl, Otus pauliani Benson, 1960, with 27.04 individuals/km 2 (Ibouroi et al . 2019).…”