|Scientific Name:||Brachyramphus brevirostris|
|Species Authority:||(Vigors, 1829)|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Contributor(s):||Day, R., Hodges, J., Irons, D., Kirchhoff, M., Kissling, M., Kuletz, K., Piatt, J. & Vincent-Lang, D.|
|Facilitator/Compiler(s):||Benstead, P., Bird, J., Calvert, R., Lascelles, B., Symes, A. & Taylor, J.|
This species has been downlisted from Critically Endangered because the rate of population decline that it is experiencing is suspected to be less rapid than previously thought. It is now listed as Near Threatened because it is nevertheless suspected to be undergoing a moderately rapid decline. Further studies are required to quantify the overall rate of decline and identify the most significant threats to the species.
Brachyramphus brevirostris has a distribution that is geographically centred on the Bering Sea, where it is rare and patchily distributed in both Russia and the USA. In Alaska (where it has been estimated that c.70% of the total population occurs [K. Kuletz in litt. 2002]) it is found from just east of Cape Lisburne south to the Aleutian Islands and east to LeConte Bay. In Russia, it is limited to the eastern Chukotskiy Peninsula in the Chukchi Sea west to Cape Schmidt and south to Anadyr Gulf, as well as Shelikov Bay in the northern Sea of Okhotsk (Day et al. 1999).
The global population has been estimated at 30,900-56,800 individuals (U.S. Fish and Wildlife Service 2010), but when factoring in the potential proportion of birds not counted in surveys, the total population may number c.48,000-82,000 individuals (M. Kirchhoff in litt. 2014).
Surveys in much of the Alaskan range indicate that populations may have declined by 80-90% in c.15 years since the early 1990s (Piatt et al. undated). In Prince William Sound, the population declined by 84% between 1989 (6,436 birds) and 2000 (1,033 birds) following a possible longer-term decline since 1972 when the population was estimated at 63,000 individuals (K. Kuletz in litt. 2002, Kuletz et al. 2003). The rate of decline in Prince William Sound between 1989 and 2004 has been estimated at 63% (5% per year) (Kuletz et al. 2011b). In the Malaspina Forelands, numbers declined by 38-75% between 1992 and 2002. Total abundance in Icy Bay, Alaska, was estimated to be 1,725-2,372 birds in 2002, suggesting a decline of 59% over a three-year period (Kissling et al. 2006). Some more recently published studies also report local declines in this species. An analysis of survey data from the Kenai Fjords, Alaska, suggests that a 90% decline occurred between 1989 and 2002; however, this analysis is hampered by changing survey methods over time, few years of survey effort and low population numbers (Arimitsu et al. 2011). In the Lower Cook Inlet, survey data suggest that the breeding population declined by 84% (26% per year) between 1993 and 1999 (Kuletz et al. 2011a). Anecdotally, the apparent recent absence of the species from LeConte Bay may indicate a change in its range in south-eastern Alaska, where the species’s abundance and distribution appears to be influenced by changes in icefields, raising concerns over its future in the region (Kissling et al. 2011).
In Glacier Bay, density estimates declined by 89.1% between 1991 and 2000, with c.2,200 birds estimated there in 1999-2000 (K. Kuletz in litt. 2002). Subsequent surveys and analysis suggest a decline of 85-90% between 1991 and 2008, with an annual trend of between -10.7% and -14.4% (Piatt et al. 2011). However, Kirchhoff et al. (2010) recorded an increase in the on-water density of the species in Glacier Bay between 1993 and 2009, from 2.07 birds/km2 to 3.55 birds/km2, although this change is not significant. This apparent stability in the population suggests that any decline had occurred before 1993, most likely in the winter of 1991-1992 (Kirchhoff et al. 2010). Similarly, Hoekman et al. (2011b) recorded an apparent increase in abundance from numbers recorded in 1999-2007 compared with numbers in 2009-2010, although earlier surveys could have suffered from negative biases. The 1993 survey was replicated in 2009 and 2010, indicating no significant change in numbers (Kirchhoff et al. 2014). Overall, however, the various studies conducted in Glacier Bay are unlikely to be comparable owing to differences in survey methods and coverage (Kirchhoff et al. 2010, Hoekman et al. 2011b). In contrast to previous analyses, surveys of Prince William Sound in 2009 showed an apparent increase on numbers in 2001 (Allyn 2012).
Many of the studies reporting declines during the 1980s and 1990s have been criticised, and Day et al. (2011) assert that there is a lack of strong evidence for a significant population change in the breeding and non-breeding populations in northern Alaska between 1970-1999 and 2000-2009, although he does not provide an alternative numerical analysis. Anecdotal evidence implies that numbers have been stable around Attu Island over recent decades (Madison et al. 2011). Increases have been recorded in other areas, such as Unalaska and Atka islands (Romano et al. 2005a,b, in Day 2011). Although Day (2011) criticises many of the analyses that have indicated very rapid declines in this species, he indicates that smaller declines in parts of or the whole of its range may still have taken place, and that shifts in the species’s geographic preferences could also account for local trends. Variation in numbers counted during localised surveys are likely to result from movements of birds over a range of temporal scales (e.g. Kirchhoff et al. 2010), and local abundance estimates may also be affected by anomalous oceanographic conditions (Arimitsu et al. 2010).
Overall, survey data indicate that declines have leveled off in recent years (J. Piatt in litt. 2012), and data collected since 1998 show mixed trend results for several study areas, with no evidence of a steep overall decline in recent years (M. Kirchhoff in litt. 2014).
Native:Canada; Japan; Russian Federation; United States
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total population was recently estimated at 30,900-56,800 individuals (U.S. Fish and Wildlife Service 2010), but when factoring in the potential proportion of birds not counted in surveys, the total population may number c.48,000-82,000 individuals (M. Kirchhoff in litt. 2014). This is assumed to equate to c.32,000-55,000 mature individuals.|
|Habitat and Ecology:||It lays a single egg on the ground amongst unvegetated scree or on cliff faces, but one recently found nest on Kodiak Island, Alaska, was on exposed bedrock (Stenhouse et al. 2008). Breeding was thought to be restricted to sites at or near the tops of mountains in glaciated regions (Day et al. 1999), but twelve active nests were recently found on Agattu in the western Aleutians, indicating that the species can nest at high densities in areas far from glaciers (Stenhouse et al. 2008). Individuals do not breed until 2-4 years of age, and may not breed every year (Day and Nigro 2004). It generally forages in different water types to the closely related Marbled Murrelet B. marmoratus, preferring but not exclusively feeding during the breeding season in turbid waters of glacial origin (Day et al. 2003). It feeds on fish and macro-zooplankton. During winter, recent work suggests that small groups are present in the Bering and Chukchi Sea in spring and autumn, but not in summer. Birds are almost always found in open leads of pack ice during early spring, but not in other times of the year, and birds are often found near Point Barrow in the autumn (M. Kissling in litt. 2010).|
There have been strong links made between this species's apparently steep decline in the late 20th century and areas of glacial recession (possibly as a result of climate change) (Piatt et al. undated, Kuletz et al. 2003, van Pelt 2005). Other threats include habitat degradation and repeated disturbance of birds owing to recreational and commercial tour-boat traffic; mortality in gill-net fisheries (documented in Prince William Sound, Yakutat Bay, and near Kodiak Island [M. Kissling in litt. 2010]); mortality from petroleum contamination (7-15% of the Prince William Sound population died as result of the ExxonValdez oil spill); and a change in prey species abundance adversely affecting piscivorous fish (Kuletz et al. 2006). Boat traffic in Glacier Bay was found to cause a 30-fold increase in flight behaviour, and nearshore densities of murrelets were temporarily suppressed by vessel passage, although this was not found to result in a persistent loss of foraging habitat (Agness et al. 2008). In 2008, the U.S. Government auctioned leases to drill for oil and gas in the Chukchi Sea off Alaska, raising the potential prospect of catastrophic oil spills in an area where the species is known to breed (BirdLife International 2008). Near-zero productivity in 1996-1998, for unknown reasons, may lead to further future declines (Day and Nigro 2004). Birds breeding in the western Aleutians have been found to have low reproductive success, with losses during the incubation period primarily due to avian predators locating unattended eggs, and chick mortality during the nestling period largely due to inclement weather (Kaler et al. 2008). According to the U.S. Fish and Wildlife Service, data from Agattu and Kodiak islands indicate that nest success has been very low (less than 10%), with few juvenile birds having been documented there, and blood chemistry analysis at Icy Bay indicates that few females there (c.10%) are breeding despite the majority (c.90%) being in physiological breeding condition (U.S. Fish and Wildlife Service 2011). It is also suspected that adult mortality is slightly elevated by losses to hydrocarbon contamination, entanglement in gillnets and high predation pressure (U.S. Fish and Wildlife Service 2011).
Conservation and research actions underway
This species is listed in the Russia Red Data Book (Van Pelt 2005, M. Kissling in litt. 2010). In the USA, the species was a candidate under the Endangered Species Act, but a recent review has concluded that it not be listed as threatened or endangered (U.S. Fish and Wildlife Service 2013). Guidelines have been drawn up in the USA to avoid disturbance of nesting birds. From 2005 to 2009 in Icy Bay, Alaska, 340 birds were banded, and 122 adults and four juveniles have been radio-tracked leading to the discovery of eight nests (M. Kissling unpublished data). The Pacific Seabird Group established the Kittlitz's Murrelet Technical Committee in 2008 to, amongst other things, act as a technical authority on ecology, distribution and ecology of the species; identify, encourage and facilitate research; address conservation problems, and; act as a liaison between research and management (M. Kissling in litt. 2010). Conservation and research actions proposed
Continue to monitor the species's population and trends in Alaska and Russia. Assess the impact of gill-net fisheries, and of boat traffic on the use of foraging areas. Develop innovative gill-net gear and fishing methods to reduce bycatch. Reduce habitat degradation and human disturbance through private sector codes of conduct. Enforce legislation to reduce the chances of oil-spills and other pollution. Tackle the threat of global climate change through international agreements. Estimate reproductive performance and other important population parameters to determine the most important factors affecting population stability. Identify and protect important courtship and nesting habitats. Identify important non-breeding areas.
|Citation:||BirdLife International 2014. Brachyramphus brevirostris. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 06 July 2015.|
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