Wildlife Research and Management - Wildlife Research
Date Published: January 26, 2001
Revised Date: January 31, 2005
Number of Pages: 194
Author(s): David R. Nysewander, Joseph R. Evenson, Bryan L. Murphie, and Thomas A. Cyra
The Washington Department of Wildlife, now part of the Washington Department of Fish and Wildlife (WDFW), was given responsibility in 1991 through legislatively provisoed funds to design and implement monitoring plans for marine birds, waterfowl, and marine mammals under the Puget Sound Ambient Monitoring Program (PSAMP). Study design was contracted out and aerial surveys began the summer of 1992. The avian abundance data emphasized in this report are to be used as indices to characterize and interpret spatial and temporal trends or patterns.
Both summer and winter aerial surveys have been conducted each year between 1992 and 1999. In 1993 the surveys were extended to include the western portion of the Strait of Juan de Fuca. These surveys sampled the entire marine shoreline of greater Puget Sound by two strata between 1993 and 1997: nearshore (< 20 meters [m]) and offshore (> 20 m). They annually covered 13% to 15% of the nearshore and 3% to 5% of the offshore marine waters in Puget Sound up to the Canadian border and out to the west entrance to the Strait of Juan de Fuca. The area covered by the summer survey was reduced, due to budget cuts, to the northern two thirds of greater Puget Sound after the summer of 1996 while the winter survey coverage has remained similar from 1993-1999. All of this survey data are capable of being mapped down to 1' blocks of latitude and longitude using global positioning satellite systems (GPS) and new intensive methods of recording observation data. The 1992-99 survey data has been incorporated into PC-based computer database and geographic information systems (GIS) as set up by the initial study design developed by contract for this program. These data are also stored using ARC software on Unix hardware in the Wildlife Resources Data Systems (WRDS) section at WDFW in Olympia. This latter data set is available through programs at WRDS (MAPSYS) in different standardized map products that provide a menu-driven input of the type of data desired for display. Either line, point, or density polygon data may be displayed from either of these database and mapping systems.
An overview of species distribution and abundance is described for summer and winter populations of marine birds and waterfowl, from PSAMP aerial surveys. Gulls and terns usually comprised 70-73% of the summer observations with four gull species comprising the majority: Glaucous-winged gull (Larus glaucescens), California gull (L. californicus), Heermann's gull (L. heermanni), and Bonaparte’s gull (L. philadelphia). Waterfowl comprised 61-67% of the winter observations. The total numbers of birds seen during the winter aerials were usually 3 times greater than those recorded during the summer, with the top ten identified species or species groups seen on the winter aerials listed in decreasing order: scoters (Melanitta perspicillata, M. fusca, and M. nigra), dunlins (Calidris alpina), gulls (Larus glaucescens, L. philadelphia, L. canus, L. thayeri), snow geese (Chen caerulescens), American wigeon (Anas americana), bufflehead (Bucephala albeola), mallards (Anas platyrynchos), western grebe (Aechmophorus occidentalis), goldeneyes (Bucephala islandica and B. clangula), and scaup (Aythya marila and A. affinis).
Key species, including alcid, loon, grebe, and diving duck species, selected by criteria described in the project's implementation plan (Nysewander et al. 1993), were examined for monitoring purposes using several parameters: indices of population estimates and associated confidence limits, densities, and counts. Temporal and spatial trends of selected species (bay and sea ducks) have been presented by this PSAMP component (1998 Puget Sound Research Conference) and these will be reviewed in this document along with additional findings for other species such as grebes and alcids. This report contains over 52 maps and additional figures displaying either densities or counts of these species during winter and summer seasons. The recent PSAMP aerial surveys have generally provided tighter confidence limits than historical data. Comparisons of future PSAMP aerial survey data with the 1992-99 PSAMP data offer the best opportunity by which population trends could be evaluated in the future.
A comparison of nearly identical winter aerial transects conducted during both 1978-79 MESA and 1992-99 PSAMP efforts revealed the following trends: 1) significant decreases (grebes, loons, scoters, scaup, oldsquaw, pigeon guillemot, marbled murrelet, cormorants, and black brant); 2) stable or more slowly decreasing patterns (rhinoceros auklets, goldeneyes, bufflehead, and gulls species); and 3) some degree of increase (harlequin ducks and probably mergansers). A preliminary review of a similar comparison with aerial survey efforts in Hood Canal between 1982-86 and 1992-99 also suggests significant declines in marine bird numbers have occurred here also. Comparisons of 1992-93 winter PSAMP aerial survey counts with USFWS aerial counts by Nisqually National Wildlife Refuge personnel were also examined for certain bays in south Puget Sound where both methodologies overlapped. Discrepancies in both methodologies and the resulting data were examined.
Comparisons of aerial and boat survey data were conducted in a limited fashion in three different ways: simultaneous transects, sequential transects, and indices derived by intensive sampling by each platform type of a selected area. The data derived from simultaneous transects and the indices derived from the intensive sampling provided the most satisfactory results. Many of the marine bird species have air to boat ratios of <1, ranging from 0.15 to 0.50 for many of the diving loon, grebe, and diving duck species on which PSAMP monitoring focuses. These correction factors are needed for interpretation of indices of density derived from PSAMP surveys if total biomass or population estimates are needed for modeling or other exercises.
The random replicate boat surveys of greater Port Orchard marine waters in February-March 1997 demonstrated other ways of gathering density indices with tighter confidence limits for species with highly clumped distributions (e.g. western grebes), as well as gathering data for small evasive species largely missed by aerial surveys such as murrelets and horned grebes.
Potential problems with data quality, error levels, software errors, and sources of these in the PSAMP aerial data were evaluated and recommendations were formulated and implemented that would correct or lessen these. Statisticians reviewed the study design during 1997 and software programs were revised or created to address the recommendations that resulted from this process.
Brief summaries are also provided for other past or ongoing project tasks and products:
- Creation of synthesized historical digital database for comparable bird surveys;
- Creation of an improved digital bathymetry database for study area;
- Survey of winter resident shorebirds;
- Survey for adult/juvenile ratios of marbled murrelets at sea in Washington;
- Monitoring of population levels of harbor seals;
- Contaminant monitoring in Puget Sound harbor seals;
- Life history and reproductive success of harbor seals;
- Resident gray whale monitoring and identification;
- Creation of MAPSYS software and map products in ARC/UNIX environment;
- Observations of other marine mammal species seen from aerial surveys.
Nysewander, D.R., J.R. Evenson, B.L. Murphie, and T.A. Cyra. 2005. Report of marine bird and mammal component, Puget Sound Ambient Monitoring Program, for July 1992 to December 1999 period [Unpublished report]. Olympia, WA: Washington State Department of Fish and Wildlife, Wildlife Management Program. 181 pp.
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