Biodiversity Guide - The Intertwine

egional conservation strategybiodiversity guideChapter 3 Major Habitat Types of the RegionWildlife Usen Federal rules, such as the Clean Water Act,Mudflats are nutrient-rich and thus denselyRiver and Harbor Act, National Environmentalpopulated with surface and subsurface invertebrates;Policy Act, and Coastal Zone Management Act.larger sandbar, mudflat, and rocky areas becausethis makes mudflats particularly important(See the Washington Department of Ecology’sthey are highly depositional, and they can also be for shorebirds. The lower Columbia River is onesummary at http://www.ecy.wa.gov/programs/tidally influenced. Logs and other debris sometimesof the most important areas in the Pacific Flywaysea/pubs/90031/index.html#RTFToC22.)are deposited on shorelines and mudflats. for migrating shorebirds, with peak counts in then Washington’s Shoreline Management Act. ThisThe sparse vegetation condition is maintained Columbia River estuary of almost 150,000 birdsact regulates alteration of wetlands associatedby regular inundation and, in some cases (such and substantial numbers using other areas alongwith the shoreline of lakes 20 acres or larger;as pure sand or rocky beaches) by low nutrient the Columbia River up to Sauvie Island and instreams with flows greater than 20 cubic feet per For More Informationlevels. Human activities also create or maintain the Willamette Valley (Pacific Coast Joint Venturesecond; and all lands within 200 feet of shorelines “Foraging Ecology of Bald Eagles in a Freshwaterthese habitats, which include river dredge spoil 1994). Reductions in the amount of mudflatsof the state (measured from the ordinary high Tidal System”deposits and—during the rainy season—plowed and shorelines in the region have had the effectwater mark), plus associated marshes, bogs, and C.M. Thompson, P.E. Nye, G.A. Schmidt, andfarm fields.of fragmenting habitat needed by shorebirds,swamps.D.K. Garcelon. 2005. Journal of Wildlifewhich travel along the major rivers of the PacificManagement 69:609-617.n Washington’s Growth Management Act ofHistorical and Current OccurrenceFlyway during migration. Shorebirds are aptly1990. This act requires cities and counties with “Foraging Shorebird Response to Trail UseThe floodplain downriver from Portland to Deer named, and are known to partition these resourcespopulations of more than 50,000 or that are around San Francisco Bay”Island historically was where most of the region’sthrough foraging strategy and bill type. Forrapidly growing (see http://www. commerce. L.A. Trulio and J. Sokale J. 2008. Journal ofmudflats and sandbars were located and is where example, birds with relatively long bills can foragewa.gov/site/395/default.aspx) to develop plans Wildlife Management 72:1775-1780.most of the remaining sandbars and mudflats are next to short-billed species without targeting thethat designate and protect “critical areas,” includingwetlands.Joint Venture Implementation Plans:found today. This floodplain includes the Vancouversame invertebrates. Gulls and terns target surfaceLower Columbia Riverlowlands, Sauvie Island and other islands prey on shorelines and mudflats and also rely onn Oregon’s statewide land use planning program Pacific Joint Coast Venture/Oregon Wetlandsin the Willamette and Columbia rivers, the Sandy these habitats for resting, as do geese and someand city and county land use plans. These address Joint Venture. 1994. West Linn, OR. http://www.River Delta, and the Ridgefield, Scappoose, and other waterfowl. Streaked horned larks are knownwetlands under a number of state policies, includingohjv.org/pdfs/lower_columbia_river.pdfGoals 5 (Open Spaces, Scenic and HistoricWoodland areas. Within the floodplain, undevelopedmainstem and island areas with shallow dredge spoils.Areas, and Natural Resources) and 16 (Estuarineto use such shorelines and mudflats, includingU.S. Shorebird Conservation Plan: Northern PacificCoast Regional Shorebird Management Planwater provide important ecological functions and Coyotes, mink, and weasel take advantage ofResources).M.S. Drut and J.B. Buchanan. 2000.are critical for young salmonids.the resulting abundance of larger prey species,n No-wake, low-speed boating rules. These boatingMudflats and sandbars have been substan-and river otter have a particular taste for therules have been implemented along severalfreshwater clams and mussels that live along riverreaches of the Columbia and Willamette rivers toreduce adverse shoreline effects.30 31tially reduced from historical levels because ofhuman activities that alter hydrology. Dams alterthe natural ebb and flow of water levels, ofteneliminating important seasonal flooding andlow flows. Dams also trap sediments upstream.Sudden water releases may wash away beaches.Dredging deepens channels and can pull sedimentsback into the river. Ships and boats createlarge wakes that can damage shorelines andproperties and wash away sandbars and mudflats.Development, dikes, and other changes in majorfloodplain areas have greatly reduced the circumstancesunder which these habitats form. Sandyand rocky beaches are particularly vulnerable toweedy species that thrive in disturbed conditions.and streambanks. A variety of small shorebirds,such as western sandpipers and greateryellowlegs, are closely associated with this habitat.Additionally, bald eagles are known to key inon sandbars and mudflats for hunting, possiblybecause these features indicate shallow-waterhabitat with readily available fish and waterfowl.Inland marine mammals such as the Californiasea lion may come ashore on sandbars and mudflatsto loaf.Conservation Strategies and OpportunitiesSeveral regulatory, nonregulatory, and planningapproaches have been implemented to protect thequantity and quality of shoreline, sandbar, andmudflat habitat:A potential future strategy to improve the quantityand quality of shoreline and mudflat habitatsis to strategically manage dams to providehydrologic conditions that are more similar tothe pre-dam conditions (i.e., implement so-calledsustainable flows projects); this would involvereleasing higher high flows and lower low flowsthan are currently allowed. A partnership ledby The Nature Conservancy and the U.S. ArmyCorps of Engineers is currently exploring suchmanagement of some Willamette River dams.The Pacific Joint Coast Venture’s LowerColumbia River plan documents the importanceof mudflats and sandbars to wildlife. The U.S.Shorebird Conservation Plan recommends theColumbia River estuary as a site of internationalshorebird significance and recognizes the WillametteValley as regionally important. Planning forconnectivity between these habitats by strategicallyaddressing hydrology in specific areas mayhelp migrating and foraging birds. Avoiding newdevelopment and diking and, where possible,removing existing structures can conserve andre-create shoreline and mudflat habitat.