Short-tailed Albatross (Phoebastria Albatrus)
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements and Literature Cited
- Biographical Summary of the Report Writer and Authorities Consulted
Population Sizes and Trends
At the beginning of the 20th century, the Short-tailed Albatross declined in numbers to near extinction, primarily as a result of hunting at the breeding colonies in Japan. Albatross were killed for their feathers and their bodies processed into fertilizer and fat; the eggs were also collected for food (Austin 1949). Although pre-exploitation worldwide population estimates of Short-tailed Albatrosses are not known, the total number of birds harvested may provide the best estimate, since the harvest drove the species to near extinction. Between approximately 1885 and 1903, an estimated five million Short-tailed Albatrosses were harvested (Austin 1949). Harvest continued until the early 1930s, except for a few years following the 1902 volcanic eruption on Torishima. By 1949, there were no Short-tailed Albatrosses breeding at any of the historically known breeding sites, including Torishima, and the species was thought to be extinct (Austin 1949, Kenyon 1950).
However, the species persisted, and in 1950 nesting of the Short-tailed Albatross was again reported on Torishima, where over 100 000 had nested during the height of exploitation (Cochrane and Starfield 1999). These were presumably birds that had been wandering the North Pacific during the final years of slaughter. In 1987 nesting was confirmed on Minami-kojima in the Senkaku Islands. There are no historical records of nesting densities from this population. There are currently an estimated 267 nesting pairs on Torishima, and 40 pairs on Minami-kojima (Hasegawa 2002, in litt.). The total global population of Short-tailed Albatross is likely around 1600 individuals (Hasegawa 2002 in litt.), as derived from estimates of the numbers of breeders and nonbreeders present in the colonies and the number of fledglings recorded since 1954 (adjusted according to the estimated survival rate). The overall population trend is one of steady increase, with breeding populations increasing, on average, at a rate of 7.5% annually on Torishima, and 11% on the Senkaku Islands (P. Sievert pers. comm. 2003).
This current growth rate is likely due to the extremely low population size compared with historical abundance. As the populations increase, density dependence could impact many of those demographic rates included in this report. For example, age of first breeding may increase, or fledging rates may decrease. However, it is likely to take many years for populations to reach these levels (Cochrane and Starfield 1999).
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