Birds and Mammals That Depend on the Salish Sea: a Compilation
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NORTHWESTERN NATURALIST 92:79–94 AUTUMN 2011 BIRDS AND MAMMALS THAT DEPEND ON THE SALISH SEA: A COMPILATION JOSEPH KGAYDOS The SeaDoc Society, University of California Davis Wildlife Health Center, Orcas Island Office, 942 Deer Harbor Road, Eastsound, WA 98245; [email protected] SCOTT FPEARSON Washington Department of Fish and Wildlife, Wildlife Science Division, 600 Capitol Way North, Olympia, WA 98501-1091 2 ABSTRACT—Efforts are underway to restore the Salish Sea, a 16,925 km inland sea shared by Washington State, USA, and British Columbia, Canada. A list of the birds and mammals that use this marine ecosystem is lacking. We compiled information from varied sources and identified 172 bird and 37 mammal species that depend on the Salish Sea marine ecosystem. Of these species, 72 bird and 29 mammal species are both highly dependent on intertidal or marine habitat as well as on marine derived food. One hundred bird species and 8 mammal species that use the Salish Sea marine ecosystem have varying degrees of dependence on the marine and terrestrial ecosystems to meet significant life history needs. These interactions between the marine and terrestrial ecosystems indicate the need to integrate marine and terrestrial restoration efforts to achieve long-term conservation of the suite of birds and mammals that use and depend on the marine ecosystem. This comprehensive list of avian and mammal fauna for the Salish Sea serves as a foundation for determining the occurrence of new species and the disappearance of others, enables selection of species as indicators for ecosystem health, and also provides a basis for identifying the mechanisms responsible for marine bird and mammal declines. Key words: birds, checklist, ecosystem health, Georgia Basin, indicator species, mammals, Puget Sound, Salish Sea The Salish Sea is a 16,925 km2 inland sea erbated in the future by the effects of climate extending from Olympia, Washington, USA, change and activities associated with a growing north to Campbell River, British Columbia, human population (Scavia and others 2002). Canada, and includes Puget Sound, the Strait Acknowledging that residents of the Georgia of Georgia, and the Strait of Juan de Fuca. It is Basin and Puget Sound region share a common bounded by mainland British Columbia and watershed, marine waters, and a common Washington State on the east, Vancouver Island flyway for migratory birds as well as common and the Olympic Peninsula on the west, and concerns over urban growth, unilateral and includes 7470 km of coastline (Gaydos and bilateral efforts by the United States and Canada others 2008). Like other coastal zones around have been underway since the late 1980s to the world (Small and Nicholls 2003), the Salish improve the health of the Salish Sea marine Sea has been dramatically altered by human ecosystem (Fraser and others 2006; Gaydos and activities including conversion of native forest others 2008). These include plans and programs and shoreline habitat to urban and residential of tribes and First Nations, and the governments development, increased water and sediment of Washington State, British Columbia, the USA, contamination, changes in food web dynamics, and Canada. the introduction of non-native and invasive As efforts increase to reverse declines in the species that alter habitat structure and native Salish Sea ecosystem, timely information will be species composition, and the potential overhar- needed on ecosystem changes. Data on wildlife vest of resources (Gaydos and others 2008). occurrence and abundance can be a useful These ecosystem pressures will likely be exac- indicator of changes in ecosystem condition or 79 80 NORTHWESTERN NATURALIST 92(2) health (Hare and Mantua 2000). Marine birds life history needs (reproduction, migration, and mammals are particularly useful indicators molt, foraging, or over-wintering habitat). We of ecosystem change because some species and included species that occur in the Salish Sea communities respond to changes in environ- regularly, species that are rarely observed, and mental conditions, are relatively easily enumer- species not typically associated with the marine ated with well-established methods, and use a environment but that depend on the marine variety of habitat types (Piatt and Sydeman ecosystem to some extent. Examples of this 2007). In addition, their diet is often correlated latter group include the Savannah Sparrow with independent measures of prey abundance (Passerculus sandwichensis) that nests in salt (Montevecchi and Myers 1995) and available marsh habitats (Cade and Bartholomew 1959), prey size distributions (Davoren and Montevec- the Snow Bunting (Plectrophenax nivalis) that chi 2003), and some are vulnerable to many over winters in salt marsh and mudflat habitats human activities (Furness and Tasker 2000). For (Dierschke and Bairlein 2004), and Black Bear example, marine bird and mammal diet has (Ursus americanus) and Black-tailed Deer (Odo- been used as an indicator of fish population coileus hemionus columbianus) that occasionally trends and potentially fishery recruitment (Mill- forage in the intertidal zone (Carlton and er and Sydeman 2004), basin-scale climate Hodder 2003). change (Hedd and others 2006), and shorter- To establish the bird list and to rank bird term climatic events (Velarde and others 2004; abundance and dependence on the marine Bertram and others 2005; Sydeman and others ecosystem, we used data from: (1) summer 2006). Marine birds and mammals are also (1992–1999) and winter (1993–2009) bird sur- sentinels for ecosystem contamination and veys conducted by Washington Department of emerging diseases and pathogens, some of Fish and Wildlife’s Puget Sound Ambient which can affect human health (Burger and Monitoring Program (Nysewander and others Gochfeld 2004; Mallory and others 2006; New- 2005) ; (2) the British Columbia Coastal Water- man and others 2007; Moore 2008). bird Survey conducted in Canadian waters from Monitoring marine bird and mammal popu- 1999 to 2009 (Badzinski and others 2008); (3) the lations could serve as an excellent indicator for Northwest Forest Plan effectiveness monitoring the health of the Salish Sea; however a list of program (Huff and others 2006; Raphael and bird and mammal species using the marine others 2007) where data are collected on most waters of this inland sea has never been marine bird species encountered; and (4) other compiled. To address this information need, available information (Butler and Campbell we use natural history information as well as 1987; Speich and Wahl 1989; Vermeer and abundance estimates, stranding data, and sight- Butler 1989; Campbell and others 1990; Butler ing reports to assemble a list of birds and and Vermeer 1994; Wahl and others 2005; Bird mammals that use the Salish Sea marine Studies Canada 2009; Kenyon and others 2009). ecosystem, and to rank their dependence on Bird taxonomy and nomenclature follow the habitat and food in this ecosystem. American Ornithologists’ Union (1998) and subsequent supplements. For mammals, pub- METHODS lished and unpublished abundance, stranding Data on species occurrence and abundance, and sighting records were used. References including scientific surveys and sighting and were species specific and are cited in Table 2. stranding data from Washington State and Mammal taxonomy and nomenclature follows British Columbia were used to identify birds Wilson and Reeder (2005). and mammals that use the Salish Sea marine Bird species with ,5 reported sightings were ecosystem. These data also were used to rank considered vagrants and were not included; all species abundance by season and to rank their confirmed mammal sightings and strandings dependence on the marine ecosystem. Marine, were included. Bird abundance was scored by estuarine, and inter-tidal environments were season: ‘‘No Reports’’ 5 never reported during considered components of the marine ecosys- season; ‘‘Rare’’ 5 sighted occasionally (,100 tem. Use of the marine ecosystem included use times/season/y); ‘‘Low’’ 5 seen regularly but of the marine environment to meet significant at low abundance 100–500/season/y; ‘‘Medi- AUTUMN 2011 GAYDOS AND PEARSON:SALISH SEA MARINE BIRDS AND MAMMALS 81 um’’ 5 seen regularly at medium abundance Of the 37 species of mammals that have been (500–5000/season/y); and ‘‘High’’ 5 seen reg- documented using the Salish Sea marine eco- ularly at high abundance (.5000/season/y). system, 29 are highly dependent, 4 are moder- Mammal abundance also was scored by season, ately dependent, and 4 have a low dependence although less quantified: ‘‘No Reports’’ 5 never on the marine or intertidal habitat and marine- reported during season; ‘‘Rare’’ 5 few sightings derived food when present (Table 2). reported; ‘‘Low’’ 5 seen regularly but at low Mammal abundance patterns are fairly uni- abundance; ‘‘Medium’’ 5 seen regularly at form throughout the year. Bird abundance, medium abundance; and ‘‘High’’ 5 seen regu- however, varies dramatically within and among larly at high abundance. Seasons used were: species depending on use of the Salish Sea for Winter 5 1 December–28 February; Spring 5 1 breeding, migrating, and overwintering. Overall March–30 May; Summer 5 1 June–15 August; bird abundance is greatest in the fall and spring, Fall 5 16 August–30 November. intermediate in the winter, and lowest in the We qualitatively assigned each species a summer. This pattern indicates the particular ranking for dependence on marine and inter- importance of the Salish Sea to migrating and tidal marine habitat when using the Salish Sea over wintering bird species. ecosystem and included habitat from the upper limit of the wave spray and splash zone through DISCUSSION the intertidal and into the deepest depths of the We documented 172 bird and 37 mammal marine zone. A score of ‘‘High’’ was assigned if species that depend on the Salish Sea marine they do not or very rarely venture from marine ecosystem for habitat or food; of these, 42% (72) or intertidal habitat; a score of ‘‘Medium’’ was of the bird and 78% (29) of the mammal species assigned if they move regularly between marine are highly dependent on the marine ecosystem.