This discussion was first published as part of the 2012 Red List update, but remains open for comment to enable reassessment in 2014.
Matsudaira’s Storm-petrel Oceanodroma matsudairae is known to breed at least on Minami-iwo-jima, and perhaps formerly on Kita-iwo-jima, both situated in the Volcano Islands (=Kazan Retto) (Chiba et al. 2007), and may also breed on the Ogasawara Islands, Japan (Brazil 1991, 2009). When not breeding, birds range widely to the territorial waters of countries in South-East Asia, South Asia, Australasia and East Africa. It is currently listed as Data Deficient on the basis that insufficient information was available for the evaluation of its status against the IUCN criteria. The species is not considered especially rare in the Indian Ocean, thus its population has been estimated at a minimum of 20,000 individuals (Brooke 2004).
The species’s apparent absence from Kita-iwo-jima since World War II could be due to egg predation by black rats Rattus rattus, which were likely introduced before the war (Sato 2001 in Chiba et al. 2007). In contrast, no rats have been detected on Minami-iwo-jima (Tsukamoto 1983 in Chiba et al. 2007). It has been recorded around the Ogasawara Islands and is assumed by some to breed there (Brazil 1991, 2009). However, it has also been suggested that the species is limited to, at most, two islands when breeding (Chiba et al. 2007), thus it may be restricted to the Volcano Islands. If it is restricted to Minami-iwo-jima and Kita-iwo-jima, its total Area of Occupancy during the breeding season will be estimated at only 8 km2.
The main island in the Volcano group, Iwo-jima, is uninhabited apart from the presence of military personnel, and it is unclear whether military activities pose potential threats to the species on Minami-iwo-jima, and perhaps Kita-iwo-jima, either through disturbance or the accidental introduction of alien predators.
Further information on this species is requested to help in the assessment of its threat status. It could qualify as Vulnerable under criterion D2 on the basis that it has a very small range, including only one or two locations, and is susceptible to the introduction of mammalian predators, which could cause the species to qualify as Critically Endangered or Extinct in a short space of time. The species may qualify for a higher threat category if evidence suggests that the population or the area and/or quality of breeding habitat are already undergoing continued declines.
Brazil, M. A. (1991) The Birds of Japan. London, UK: Christopher Helm.
Brazil, M. (2009) Field Guide to the Birds of East Asia. London, UK: Christopher Helm.
Brooke, M. (2004) Albatrosses and Petrels across the World. Oxford, UK: Oxford University Press.
Chiba, H., Kawakami, K., Suzuki, H. and Horikoshi, K. (2007) The Distribution of Seabirds in the Bonin Islands, Southern Japan. J. Yamashina Inst. Ornithol. 39: 1-17.