Justification of Red List Category
This species has been assessed as Vulnerable on the basis that it occupies a tiny range when breeding, probably on just two islands, and is thus susceptible to stochastic events and the impacts of human activities.
It is described as not especially rare in the Indian Ocean, suggesting that the global population numbers a minimum of 20,000 individuals (Brooke 2004).
The population trend is difficult to determine because of uncertainty over the main threats to the species.
Hydrobates matsudairae is only known to breed on the Volcano Islands (=Kazan Retto), southern Japan. It breeds at least on Minami-Iwo-Jima, and perhaps formerly on Kita-Iwo-Jima (Chiba et al. 2007). It has also been recorded around the Ogasawara Islands and is assumed to breed there (Brazil 1991, 2009), but this requires confirmation. After the breeding season, it is thought to move south across the equator, perhaps to the Timor Sea off north-west Australia, and then west into the Indian Ocean, where it winters mostly in the equatorial belt around the Seychelles and west to Somalia and Kenya. Some birds may winter off north-east New Guinea. There is an unverified record off the coast of Sabah, Malaysia (D. Bakewell in litt. 2012). No quantitative data are available on its population, although it is reported to be locally common in its breeding range, and its abundance in the Indian Ocean has led to the suggestion that the global population numbers a minimum of 20,000 individuals (Brooke 2004).
It is colonial, nesting in burrows on high ground (del Hoyo et al. 1992). Breeding is thought to begin in January, with most fledging taking place in June (del Hoyo et al. 1992). In the non-breeding season it is generally pelagic, occurring far from the coast (del Hoyo et al. 1992).
House rats Rattus rattus became established on Kita-Iwo-Jima apparently following the Second World War, and are considered to have caused local extinctions (Kawakami 2008): there do not appear to be any breeding records of Matsudaira's Storm-petrel from the island in recent decades (Chiba et al. 2007). House rats are likely to be causing continuing mortality to birds attempting to nest on the island. There a real risk of introduction to what may be the only remaining breeding island (Chiba et al. 2007), which would likely have devastating consequences.
Conservation Actions Underway
No targeted conservation actions are known for this species.
Text account compilers
Symes, A., Taylor, J., Crosby, M., Hermes, C., Martin, R., Miller, E., Fjagesund, T., Benstead, P., Peet, N., Stuart, A.
Bourne, W., Bakewell, D.
BirdLife International (2020) Species factsheet: Hydrobates matsudairae. Downloaded from http://www.birdlife.org on 08/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/07/2020.