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Brachyramphus marmoratus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES CHARADRIIFORMES ALCIDAE

Scientific Name: Brachyramphus marmoratus
Species Authority: (Gmelin, 1789)
Common Name(s):
English Marbled Murrelet
Taxonomic Notes: Brachyramphus marmoratus (Sibley and Monroe 1990, 1993) has been split into B. marmoratus and B. perdix following AOU (1998).

Assessment Information [top]

Red List Category & Criteria: Endangered A2bc+3bc+4bc ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bertram, D., Burger, A.E., Kuletz, K. & Piatt, J.
Facilitator/Compiler(s): Benstead, P., Calvert, R., Derhé, M., Gilroy, J.
Justification:
This species is still abundant, but it is treated as Endangered because its population is estimated to have undergone a very rapid reduction, which is expected to continue, owing to a variety of threats.

Geographic Range [top]

Range Description: Brachyramphus marmoratus occurs in the USA and Canada in California, Oregon, Washington, British Columbia, south-east Alaska, Prince William Sound, Kenai Peninsula, Lower Cook Inlet, Barren Islands, Afognak and Kodiak Islands, the Alaska Peninsula and the Aleutians locally to Andreanof and Near Islands (Gaston and Jones 1998). In Alaska (85% of the population), historical estimates place the population at c. 750,000 individuals, though when trend estimates are applied to this figure it gives an estimated 2006 population of c. 271,000 individuals (Piatt et al. 2007). The British Columbia population was previously thought to be c. 54,000 - 92,500 (Piatt et al. 2006) but recent radar counts suggest the population may in fact be c. 72,600-125,600 birds (Bertram et al. 2007, A. Burger in litt. 2012). This higher estimate is likely due to differences in survey methodology as opposed to a genuine population increase. The population in Washington, Oregon and California is estimated at 14,631-20,952 individuals (Falxa et al. 2009). The greatest historical decreases have occurred in Washington, Oregon and California, and these continue (A. Burger in litt. 2012). Declines are also reported in British Columbia and south-east Alaska (Perry 1995). Trend analyses conducted during 2000-2007 suggests a decline of c.15% over the period in Washington, Oregon, and California (Falxa et al. 2008), a decrease of c. 70% in Alaska from the 1980s to 2006 (Piatt et al. 2006), and a 40% decline in some parts of British Columbia in 1982-1992 (Kelson et al. 1995). At-sea surveys over the past 25 years in British Columbia suggest declines of c. 1% per year (Piatt et al. 2006) although  radar surveys suggest the population may have been relatively stable since 1999 (COSEWIC 2012). Availability of nesting habitat in British Columbia, which is strongly correlated with local breeding populations (Burger 2001, Burger et al. 2004), has declined by 22%  between  1978 and 2008 and is continuing (COSEWIC 2012).

Countries:
Native:
Canada; United States
Vagrant:
Mexico
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: COSEWIC (2012) estimated the total population to number 358,200-417,500 individuals, rounded here to 350,000-420,000 individuals, based on 271,000 individuals in Alaska (Piatt et al. 2007), 72,600-125,600 in British Columbia (Bertram et al. 2007), and 14,631-20,952 individuals in Washington, Oregon and California (Falxa et al. 2009).

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: It nests in old-growth trees (up to 60 km inland) and on the ground (sparsely where trees are absent, suboptimal) (Piatt and Ford 1993, Ralph 1995, Gaston and Jones 1998, Burger 2002, McShane et al. 2004, Piatt et al. 2006), with the breeding season stretching between March and September in California, April and September in British Columbia, and May and September in Alaska (Piatt et al. 2006). Forest areas with multiple canopy layers and (in southern parts of its range) high mistletoe abundance are strongly preferred. Research in British Columbia shows that in areas where forest habitat is relatively plentiful the species seldom re-use the same trees as nest sites, whereas in areas where logging has reduced old-growth there is a higher proportion of nest tree re-use (Burger et al. 2009). The species has been suggested to tolerate substantial fragmentation (Harrison 2008), however, it has been shown to suffer increased predation and disturbance at forest edges adjacent to recently cleared areas, compared with forest edges adjacent to regenerating or riparian areas (Malt and Lank 2007, 2009). Multiple radar studies have shown a significant correlation between numbers of birds entering watersheds and the areas of suitable forest habitat within those watersheds (Burger 2002, Burger et al. 2004). The species may prefer breeding sites with warmer sea-surface temperatures as annual density and productivity estimates during 1995-2007 have been found to increase with increasing sea surface temperature in the San Juan Archipelago, Washington (Raphael and Bloxton 2008), although a study in Northern California, suggests that reproductive effort may decrease with warmer sea-surface temperatures (Bigger and Chinnici 2008). Breeding is mid-March to early September in California, but more compressed further north (Hamer and Nelson 1995a, 1995b, Gaston and Jones 1998, Burger 2002). The diet is sandlance, herring, other small schooling fish and, in winter, invertebrates (Gaston and Jones 1998, Piatt et al. 2006). Chicks are generally fed large subadult or adult prey rather than juveniles or larvae (Piatt et al. 2006). It feeds in near-shore habitats up to 1.4 km offshore, in sheltered waters, lagoons and sometimes inland lakes (Carter 1986, Hunt 1995, Gaston and Jones 1998, Burger 2002, Hebert and Golightly 2008). Daily movements to feeding areas can be up to 250 km in exceptional cases (Whitworth et al. 2000) but are normally about 30 km (Burger 2002, Piatt et al. 2006). Radio-marked birds from Redwood Creek in North California moved a maximum average distance of 99 km alongshore, with males travelling further than females, and non-breeding males travelling further than breeding males perhaps in search of mates or nesting habitats. Average home range size was 505 km2, again being greater for males than females (Hebert and Golightly 2008). Individuals exhibit plasticity in their foraging behaviour, foraging closer to shore and increasing dive rates during nesting (Peery et al. 2009). Marbled Murrelets most often forage in pairs (Piatt et al. 2006). Individuals in the northern part of its range may travel south during the non-breeding season, a movement which likely reflects the availability of prey (Piatt et al. 2006).

Systems: Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s): Many areas of remaining old-growth forest used as nesting habitat are slated for logging. Loss of nesting habitat is strongly linked with declining populations through most of the species range (Burger 2002, Burger and Waterhouse 2009, Piatt et al. 2006). Multiple radar studies have shown that when breeding habitat is reduced by logging, the birds do not simply relocate to remaining forest patches in higher densities, but suffer a population decline (Burger 2001). This strongly suggests that population declines through much of its range have been driven, at least in part, by loss of nesting habitat (Burger 2002). The species has been found to suffer increased corvid predation and disturbance at forest edges adjacent to recently cleared areas (Burger 2002, Malt and Lank 2007, 2009). Juvenile recruitment off Vancouver Island was significantly reduced in a year of low marine productivity and prey availability (Ronconi and Burger 2008)  Since the collapse of the Pacific sardine fishery, prey quality and abundance has declined, with lower trophic-level prey (e.g. krill) now dominating the pre-breeding diet in California (Becker and Bessinger 2006). This has resulted in a lower proportion of individuals reaching breeding condition, and therefore lower population productivity. This factor, combined with high rates of nest predation by corvids, is thought to be the primary cause of recent declines in California (Peery et al. 2004). Nylon, monofilament gill-nets in shallow waters and oil-spills (e.g. Exxon Valdez, Nestucca and New Carissa) also cause considerable mortality (Piatt and Naslund 1995, Nelson 1997, Gaston and Jones 1998, Burger 2002, Titmus and Smith 2008). A 2010 study suggests genetic divergence of the species in central California, despite c. 7% of this population being classified as migrants, as individuals dispersing from northern populations contribute relatively few young to the central California population (Peery et al. 2010).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
It is Threatened in all range states except Alaska. Detailed conservation recommendations were made in 1995 (Ralph et al. 1995). Federal land-use in the USA is regulated, areas for management identified, and some temporarily removed from logging (Nelson 1997), though the protected status of old-growth forest in California is currently under review by the USFWS in response to a timber-industry-led petition. In July 2008, the USFWS proposed a limited revision to critical habitat for the species in Oregon and Northern California. The Pacific Seabird Group (PSG) filed an objection to the removal of critical habitat designation in some counties in Oregon, but concurred with the proposed critical habitat revisions in northern California and southern Oregon (Harrison 2008). USFWS initiated a status review of the species in 2008, which will also function as a 5-year status review (Harrison 2008). In Canada there has been extensive research, a (now outdated) Recovery Plan (Kaiser et al. 1994), some (relatively minor) habitat protection under the British Columbia Forest and Range Practices Act, more extensive protection of forest habitat under various Land Use agreements and a radar monitoring plan developed by the Canadian Marbled Murrelet Recovery Team (CMMRT 2003). The Canadian Marbled Murrelet Recovery Team developed a Recovery Strategy to be compliant with the Canadian Species at Risk Act. This Recovery Strategy was based on a thorough conservation assessment (CMMRT 2003) approved by the multi-stakeholder team and submitted to the Canadian and British Columbia governments in 2006, but has been shelved since then (A. E. Burger in litt. 2012). The Canadian Marbled Murrelet Recovery Team (CMMRT) also oversaw the completion of a SARA-compliant Marbled Murrelet Nesting Habitat Recovery Action Plan dealing with forest habitat; this too was submitted to the governments in 2006 and has since received no attention (A. E. Burger in litt. 2012). The Department of Natural Resources (WDNR) began developing a Marbled Murrelet Long-Term Conservation Strategy in 2007 (Escene 2007). The Northwest Forest Plan (2006) is expected to ensure the protection of a large proportion of important habitats in the USA (Raphael 2006). Extensive areas of suitable forest nesting habitat have been set aside in conservancies on the northern and central mainland and in Haida Gwaii (formerly Queen Charlotte Islands) (COSEWIC 2012). Smaller areas are being protected by other forestry and conservation measures.  Overall, an estimated 35% of the 1,826,828 hectares of  suitable habitat in all of British Columbia (based on the Canadian Marbled Murrelet Recovery Team modeling criteria [CMMRT 2003]) had been protected under various measures by 2011 (COSEWIC 2012). In 1998, the Exxon Valdez Trustee Council protected 179 km2 of Afognak Island (BBC Wildlife 1999 172: 23). In 2007, 1,569 ha of forested land on the Oregon Coast was acquired under conservation easement for the species (amongst others), part funded by the New Carissa oil-spill funds (Escene 2007). Between 1998 and 2002, 507 Marbled Murrelets were radio-tracked in British Columbia (Barrett et al. 2008) and during 2005-2007, 111 birds were radio-tracked at Port Snettisham, Alaska, to determine nesting habitat, activity patterns and distribution (Nelson et al. 2008). A recommended protocol for surveying the species in forests was published in 2003 by PSG (Mack et al. 2003). In British Columbia standard protocols have been developed for various survey methods (RIC  1997, Burger 2004). Research has shown that habitat management at relatively fine scales may provide conservation benefits (Horton 2008) and that the species would benefit from a reduction in the amount of hard edges (recent clear-cuts) at both patch and landscape scales (Malt and Lank 2007, 2009).

Conservation Actions Proposed
Survey potential nesting habitat. Collect data on the ratio of juvenile to adult birds from sites throughout the range, and monitor over time, as this is thought to be a reliable indicator of productivity (Peery et al. 2007). Research means of improving the abundance of high quality food, e.g. small fish, during the pre-breeding period. Minimise damage to fish stocks and feeding areas (RENEW Report 1999 9: 20). Conduct research on the behaviour of migrants to determine the extent to which dispersal results in gene flow and prevents declines in resident populations (Peery et al. 2010). Complete and implement the SARA-compliant Canadian Marbled Murrelet Recovery Strategy and the Action Plans proposed therein  (CCMMRT 2003). Protect nesting habitat (K. J. Kuletz in litt. 1999). Move campgrounds away from old-growth areas in Californian State Parks, in order to reduce predator populations in breeding areas. Reduce oil-spills, gill-net mortality and logging (K. J. Kuletz in litt. 1999). List as Threatened in Alaska (K. J. Kuletz in litt. 1999).


Citation: BirdLife International 2012. Brachyramphus marmoratus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 22 December 2014.
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