Data Zone
Justification of Red List category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Population justification
The global population is estimated to number c.1,000,000-2,000,000 individuals (del Hoyo et al. 1996). National population estimates include: c.100-10,000 breeding pairs and c.1,000-10,000 wintering individuals in China; c.100-10,000 breeding pairs and c.1,000-10,000 wintering individuals in Korea; c.100-10,000 breeding pairs and c.1,000-10,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 wintering individuals in Russia (Brazil 2009).
Trend justification
In North America, the population trend is decreasing (based on BBS/CBC data: Butcher and Niven 2007). The global population is also suspected to be in decline owing to predation by invasive species.
The Ancient Murrelet can be found from the Yellow Sea (islands off China and Korea), through the Russian Pacific coast and the Aleutian Islands to the Haida Gwaii archipelago of British Columbia (Canada), where about half of the world population breeds. It can be found as far south as the southern coast of California (U.S.A.) (del Hoyo et al. 1996).
Habitat This species if found offshore and along rocky sea coasts. It breeds on islands with dense vegetation. It forages mainly in offshore waters to the edge of the continental shelf, but may also be found inshore, where oceanographic processes concentrated food near the sea surface. It winters well offshore, often off the shelf break, but also over inshore waters, where food concentration is high. Its distribution is determined largely by concentrations of planktonic crustaceans and small fish.
Diet Its diet is comprised mainly of planktonic crustaceans and small larval fish, with the specific prey species varying both geographically and temporally. Feeding usually occurs in small flocks by diving.
Breeding Individuals arrive in the vicinity of colonies a month before laying, from early spring to mid-summer depending on the locality. It is colonial, but occurs at low densities, and is often associated with other alcids. It is nocturnal at colonies, nesting in burrows excavated in soil, but also in rock crevices and cavities and occasionally in holes dug by other subterranean nesters (del Hoyo et al. 1996).
Climate change probably poses the greatest threat to the species. The 1997–1998 El Niño Southern Oscillation (ENSO) event had a strong effect on breeding success, reducing the number of chicks per pair from more than 1.4 to below 1, mostly caused by desertions before incubation began. Gaston and Smith (2001) found a positive correlation between May sea surface temperature (SST) and the slope of the regression of chick mass at colony departure on a particular date for a given year. Climate change is thought to be driving declines or fluctuations, yet further changes in SST and more frequent ENSO patterns in the future could accentuate the risk to the species.
Invasive species are present in parts of the range, exerting negative impacts on local populations through predation. Breeding populations have been declining on both islands where rats Rattus spp. are present; the Lyell Island population declined by 22% over a 10-year period, and the one on Kunghit Island declined by more than 50% over seven years and appeared to be completely extirpated by 2004. Estimates of breeding populations in three rat-free colonies suggest stable or increasing numbers over 18- and 11-year periods (Regehr et al. 2007). The suggestion that racoons Procyon lotor have been responsible for many seabird losses over the last decades is supported by changes in predation levels recorded between years and corresponding seabird population trends. Predation levels were similar in 1990 and 1991, in the presence of raccoons, but declined by 80% in 1992, following the removal of three raccoons. Raccoon predation represents a conservation threat of international significance, because the Queen Charlotte Islands contain the majority of the world's Ancient Murrelet population, as well as substantial populations of several other burrow-nesting species that are also susceptible to raccoon predation (Hartman et al. 1997).
Text account compilers
Fjagesund, T., Butchart, S., Martin, R., Ekstrom, J., Calvert, R., Miller, E.
Recommended citation
BirdLife International (2024) Species factsheet: Ancient Murrelet Synthliboramphus antiquus. Downloaded from
https://datazone.birdlife.org/species/factsheet/ancient-murrelet-synthliboramphus-antiquus on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.