|Red List Category & Criteria:
||Butchart, S. & Symes, A.
||Bourne, W., Croxall, J., Lavers, J., Oka, N., Sato, K., Sato, M., Takeishi, M., Uematsu, S. & Watanuki , Y.
||Ashpole, J, Butchart, S., Calvert, R., Ekstrom, J., Moreno, R., Newton, P., Symes, A., Taylor, J.
The prevalence of threats from introduced predators on the species's main breeding grounds in Japan and additional factors such as fisheries bycatch and human disturbance suggests that the species is in overall decline. It is therefore precautionarily classified as Near Threatened as it almost meets the requirements for listing as threatened under criteria A2abe+3be+4abe. Further data are required from across its range to quantify the trend.
|Previously published Red List assessments:|
- 2016 – Near Threatened (NT)
- 2015 – Near Threatened (NT)
- 2012 – Least Concern (LC)
- 2009 – Least Concern (LC)
- 2008 – Least Concern (LC)
- 2004 – Least Concern (LC)
- 2000 – Lower Risk/least concern (LR/lc)
- 1994 – Lower Risk/least concern (LR/lc)
- 1988 – Lower Risk/least concern (LR/lc)
|Range Description:||This species is found in the western Pacific, breeding on the coast and on offshore islands of Japan, Russia, and on islands off the coasts of China, North Korea and South Korea. It migrates south during winter, being found off the coasts of Vietnam, New Guinea, the Philippines, Australia, southern India and Sri Lanka (del Hoyo et al. 1992, Praveen et al. 2013). The global population has been estimated to number c. 3,000,000 individuals (Brooke 2004). In Japan, where it is thought that the majority of the species’s world population breeds, there are 11 islands that are each thought to be inhabited by more than 10,000 breeding pairs (Oka 2004). A recent survey on the island of Nakanokamishima estimated the population at 5,566 individuals and 2,783 nests (Yamamoto et al. 2015). According to islanders, the species appears to have been declining rapidly on Mikura-jima, but quantitative data are not available (S. Uematsu in litt. 2012). The prevalence of threats from introduced predators suggests that the species is in overall decline; however, further data are required from throughout the species’s range to assess the current population trend.|
Australia; Brunei Darussalam; China; Guam; Indonesia; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Malaysia; Micronesia, Federated States of ; Northern Mariana Islands; Palau; Papua New Guinea; Philippines; Russian Federation (Eastern Asian Russia); Solomon Islands; Taiwan, Province of China; Thailand; Timor-Leste; Viet Nam
India; Israel; Jordan; Maldives; Sri Lanka; United States
Present - origin uncertain:
Marshall Islands; Nauru; New Caledonia; Norfolk Island; Vanuatu
|♦ Continuing decline in area of occupancy (AOO):||Unknown|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||45800000|
|♦ Continuing decline in extent of occurrence (EOO):||Unknown||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Continuing decline in number of locations:||Unknown|
|♦ Extreme fluctuations in the number of locations:||No|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Brooke (2004) estimated the global population to number c.3,000,000 individuals, while national population estimates include: c.100-10,000 breeding pairs, c.50-1,000 individuals on migration and c.50-1,000 wintering individuals in China; c.100,000-1,000,000 breeding pairs, c.10,000 individuals on migration and c.10,000 individuals on migration and c.50-1,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).|
Trend Justification: The population is suspected to be in decline, owing primarily to predation by introduced mammals (S. Uematsu in litt. 2012); however, the rate of decline has not been quantified.
|Current Population Trend:||Decreasing|
|♦ Continuing decline of mature individuals:||Unknown|
|♦ Extreme fluctuations:||No||♦ Population severely fragmented:||No|
|♦ Continuing decline in subpopulations:||Unknown|
|♦ Extreme fluctuations in subpopulations:||No||♦ All individuals in one subpopulation:||No|
Some level of negative impact from introduced rats Rattus species can be expected on at least three of the Japanese islands occupied by the species (M. Sato in litt. 2011). It appears to suffer significant impacts from rats on Mikura-jima, which is populated by c.300 people and is popular with tourists, thus making an eradication programme problematic and the subsequent reintroduction of rats more likely (Oka et al. 2002, J. Croxall in litt. 2011). Feral cats may also be inflicting increasing mortality on the Mikura-jima population, through predation on chicks, young birds and adults (N. Oka per M. Sato in litt. 2012, S. Uematsu in litt. 2012). Both Black Rats Rattus rattus and Brown Rats R. norvegicus are potentially affecting a colony of c.150,000 individuals breeding on Okino-shima Island (M. Takeishi per M. Sato in litt. 2011). On Sasudo, South Korea, the species is threatened mainly by predation by R. norvegicus (Lee 2010). Rats, cats and human disturbance may threaten the species on Socheong Island (Birds Korea 2010). In addition to these threats, the species is also susceptible to fisheries bycatch (Birds Korea 2010, J. Croxall in litt. 2011). Global climate change may be affecting the distances travelled to feeding sites, potentially impacting whole colonies, but further research is required (S. Uematsu in litt. 2012). Research suggests the Fukushima nuclear accident may have had negative impacts on birds breeding on Mikura Island, with reduced vitamin A levels detected in chicks (Uematsu et al. 2014). The researchers suggest that additional negative impacts may be expected in the population in the future.