BirdLife Species factsheet for Romblon Boobook: http://datazone.birdlife.org/species/factsheet/romblon-boobook-ninox-spilonotus
Romblon Boobook, Ninox spilonotus, is a recently-split hawk-owl endemic to the Philippines. It is found in primary and taller secondary forest on the islands of Tablas and Sibuyan, with unconfirmed reports of the species on Romblon (Allen 2006, König and Weick 2008, Rasmussen et al. 2012). Its habitat, on both islands where it is known to occur, is under threat as a result of logging, with Sibuyan also being affected by gold mining (Goodman and Ingle 1993, del Hoyo et al. 2009, M. Wallbank verbally 2009 to D. Allen, in Rasmussen et al. 2012, D. Allen in litt. 2013). Thus, the species has been considered to be in decline.
Given this decline, the species is currently listed as Vulnerable under criterion C2a(i) as the total population size has been thought to fall in the range of 1,000-2,4999 mature individuals, with <1,000 mature individuals per sub-population (see BirdLife International 2017). It has been suggested, however, that this may be an overestimate and each island may only contain 100-200 mature individuals given the amount of cover on the islands (R. Hutchinson in litt. 2016). Congeners can have range sizes up to 206 or even 307 ha (Olsen et al. 2011, Pryde and Green 2016), and bird density can be low on Sibuyan (D. Allen in litt. 2013) and so it is plausible that sub-population sizes may be this low. If this was accepted the overall population size would be <500 mature individuals, and so would fall into the range of 250-999 mature individuals, with <250 mature individuals per population. This, combined with an inferred continuing decline would mean that the species would warrant listing as Endangered under criterion C2a(i). We therefore request any comments and further information regarding the potential population size of this species to see whether it does warrant uplisting to Endangered.
Allen, D. 2006. New records and other observations of birds on the island of Tablas. Forktail 22: 77-84.
BirdLife International. 2017. Species factsheet: Ninox spilonotus. Downloaded from http://www.birdlife.org on 07/04/2017.
del Hoyo, J.; Elliott, A.; Christie, D. 2009. Handbook of the Birds of the World, vol. 14: Bush-shrikes to Old World Sparrows. Lynx Edicions, Barcelona, Spain.
Goodman, S. M.; Ingle, N. R. 1993. Sibuyan Island in the Phillipines-threatened and in need of conservation. Oryx 23: 174-180.
König, C.; Weick, F. 2008. Owls of the World. Second Edition. London, UK: Christopher Helm.
Rasmussen, P.C., Allen, D.N.S., Collar, N.J., DeMeulemeester, B., Hutchinson, R.O., Jakosalem, P.G., Kennedy, R.S., Lambert, F.R. and Paguntalan, L.M. 2012. Vocal divergence and new species in the Philippine Hawk Owl Ninox philippensis complex. Forktail 28: 1-20.