ACCESS NUMBER: 16950 

STUDY TITLE: Monitoring Beaufort Sea Waterfowl and Marine Birds. 

REPORT TITLE: Monitoring Beaufort Sea Waterfowl and Marine Birds, Aerial Survey Component. 

CONTRACT NUMBER(S): Intra-agency Agreement 16950. 

SPONSORING OCS REGION: Alaska. 

APPLICABLE PLANNING AREA(S): Beaufort Sea 

FISCAL YEAR(S) OF PROJECT FUNDING: 1999-2001. 

COMPLETION DATE OF REPORT: January 2002. 

COST(S): FY 1999: $12,000; FY 2000: $142,992; FY 2001: $9,008; CUMULATIVE PROJECT COST: 

$164,000. 

PROJECT MANAGER(S): Julian B. Fischer. 

AFFILIATION: U.S. Fish and Wildlife Service, Migratory Bird Management. 

ADDRESS: 1011 E. Tudor Road, Anchorage, AK 99503. 

PRINCIPAL INVESTIGATORS(S)*: Dirk V. Derksen, Chief, Wetlands and Terrestrial Ecology Branch, 

USGS-BRD, Alaska Science Center, 1011 E. Tudor Road, Anchorage, AK 99503. 

KEY WORDS: Beaufort Sea; marine birds; sea ducks; lagoons; Long-tailed Duck; Clangula hyemalis; 

Common Eider; Somateria mollissima; King Eider; Somateria spectabilis; Spectacled Eider; Somateria 

fischeri; Northstar; aerial survey; OCS, offshore. 

BACKGROUND: Oil and gas development within the Northstar Unit began in winter 2000 and was 

expected to increase potential disturbance to marine birds in the region. These waters provide breeding 

and molting habitat, and migratory pathways for marine birds. The U.S. Department of Interior began 

investigations to assess impacts of human activities on the distribution and density of Long-tailed Ducks 

in Beaufort Sea lagoons and eiders in offshore waters adjacent to planned developments. 

OBJECTIVES: 

1. Monitor Long-tailed Ducks and other species within and among “Industrial” and “Control” areas 

using existing protocol (OCS-MMS 92-0060). 

2. Use data from 1999-2000 and data collected by Johnson and Gazey (1992) in 1990-1991 to 

compare Long-tailed Duck population trends between “Industrial” and “Control” areas, and to 

describe the relationship between distribution patterns and human activities. 

3. Expand the Near-shore survey area to encompass habitats between the original “Industrial” and 

“Control” areas, and sample Near-shore Marine habitat from Oliktok Point to Brownlow Point to 

delineate small-scale distribution patterns of marine birds throughout the expanded study area. 

4. Correlate variation in marine bird populations with environmental factors, human activities, and 

temporal and spatial variables. 

5. Implement an Offshore survey that targets Spectacled (Somateria fischeri), Common (S. 

mollisima) and King Eiders (S. spectabilis). 

6. Document distribution patterns of marine birds within the Offshore survey area. 

DESCRIPTION: U.S. Fish and Wildlife personnel completed a series of 12 Near-shore and 6 Offshore 

aerial surveys in 1999-2000. The Near-shore surveys followed a standard data collection protocol (OCSMMS 92-0060). Surveys were completed between mid-July and early September in 1999 and 2000 (6 

each year). A single-engine Cessna and a twin-engine Aero Commander were used as survey platforms. 

Survey altitude and speed were maintained at 30-45 m and 160-180 km/hr, respectively. All birds within 

200 m of either side of the aircraft were recorded along with corresponding weather variables. 
Observations were recorded as voice inputs into an onboard computer that received continuous position 

and time data from a Global Positioning System (GPS). ArcInfo coverages were generated from bird 

location files and loaded into ArcView to produce distribution maps. General linear models outlined in 

existing analysis protocol (OCS-MMS 92-0060) were used to compare population trends between 

“Industrial” and “Control” areas and to describe the relationship between bird density and human 

activities. 

Near-shore surveys in 1999-2000 sampled a broader area than that described in protocol MMS 92-0060. 

This provided data from an expanded Near-shore study area to document distribution patterns of 11 

marine bird taxa within Near-shore Marine, Barrier Island, Mid-lagoon, and Mainland Shoreline Habitats. 

The Offshore survey provided estimates of marine birds densities within and adjacent to the Northstar, 

Liberty and Sandpiper Units. Transect lines ran perpendicular to shore to an extent of approximately 60 

km from shore. Offshore surveys were conducted at the end of June, July, and August in each year to 

coincide with estimated peaks of offshore abundance for local breeding eiders (i.e. exodus of breeding 

males [late June], failed or non-breeding females [late July], and successful breeding females with broods 

[late August]). A twin-engine Aero Commander was used as a survey platform for the Offshore survey. 

Most surveys were flown at 45m and 160km/hr. Due to safety concerns, however, surveys in June 1999 

and August 2000 were flown at approximately 90m and 200km/hr. 

The Offshore study area was divided into 8 strata: 4 areas (Cape Halkett to Oliktok Point [transects 23-

36], Oliktok Point to Prudhoe Bay [transects 13-22], Prudhoe Bay to Tigvariak Island [transects 3-12], and 

Tigvariak Island to Brownlow Point [transects 1-2, 37-43]), each divided into 2 water depth classes 

(shallow [<10m], and deep [>10m]). General distribution patterns and components of variation in density 

were identified using general linear model techniques. 

SIGNIFICANT CONCLUSIONS: We detected a significant decrease in Long-tailed Duck density within 

the Near-shore study area between 1990-2000. This finding substantiated concerns expressed by 

Johnson and Gazey (1992) who detected a non-significant downward trend in Long-tailed Duck densities 

between 1989-1991. While densities region-wide appear to have decreased overall, we did not find 

sufficient evidence to indicate that trends were significantly different between the “Industrial” and “Control” 

areas. Similarly, survey data suggest that human activities, such as boat traffic, low-level aircraft, and 

human activities on land did not significantly alter the distribution patterns of Long-tailed Ducks. 

These tests may fail to detect effects of human activities on bird density and distribution even if they exist. 

Reasons for low power to detects such effects include inherent stochasticity in sea duck populations, high 

standard errors associated with aerial survey techniques, long-term changes in barrier island habitat, 

intrusion of human activities into the “Control” site, and unidentified components of variation. 

We identified several areas that appear to be important to marine birds. Harrison Bay, particularly the 

deep-water strata, supported the highest concentrations of King and Spectacled Eiders. Moreover, this 

region appears to be important for Scoters, and Red-throated and Yellow-billed Loons. Barrier Island 

habitat supported high concentrations of Long-tailed Ducks and Common Eiders. In particular, Barrier 

Island Habitat among the Stockton Islands had consistently high densities of these species. Mainland 

shoreline between Bullen Point and Point Thomson supported high densities of Long-tailed Ducks relative 

to other areas in this habitat. Finally, Scoters showed a strong affinity to Mid-lagoon habitat in western 

Simpson Lagoon. 

Given sufficient annual replication, the Near-shore survey protocol provides a means to monitor trends in 

molting Long-tailed Duck densities among specific areas and can establish relationships between 

distribution patterns and human activities; however, this approach is limited. For example, the protocol 

cannot be used to measure population abundance or habitat preference. Moreover, the protocol is 

inappropriate to apply to other marine bird species that may be of management concern. One alternative 

is to measure behavioral responses to disturbances of known size and duration. This direct measure 

could provide researchers an opportunity to document immediate changes in distribution within a 

controlled setting. Additionally, this approach may help identify what activities have measurable effects 

and predict the potential duration of these effects. 
If multi-species abundance and habitat preference information is of interest, then monitoring efforts 

should use a sampling design that includes systematic transects with random starting points. This 

approach would provide an unbiased sample of multi-species distribution and density within the area of 

interest. In addition to helping understand how future developments may affect marine birds, such an 

approach would assist modeling efforts that predict the impact of potential oil spills. 

STUDY RESULTS: General linear models revealed a significant decrease in densities of Long-tailed 

Ducks from 1990-2000 with the largest decrease occurring between 1990 and 1991. Although densities 

decreased throughout the Near-shore study area, there was no detectable change in relative densities of 

Long-tailed Ducks in “Industrial” vs. “Control” areas. Moreover, changes in Long-tailed Duck distribution 

patterns were not related to human activities. 

Long-tailed Ducks were the most abundant species in the near-shore environment. Within this area, 

densities were highest in Barrier Island habitat, particularly among the Stockton Islands. Distribution 

patterns were documented for 10 additional marine bird taxa in near-shore waters. 

The Offshore survey revealed general patterns of Eider distribution. Common Eider densities were 

highest in shallow-water areas throughout the study areas, whereas King Eiders were generally found in 

deep waters of Harrison Bay. Similarly, Spectacled Eiders were seen in large flocks in Harrison Bay; yet 

sightings were relatively uncommon. Offshore survey data also indicated that while Common Eider 

densities remained relatively stable through summer, King and Spectacled Eider densities peaked in July. 

The timing and location of King and Spectacled Eider concentrations supports the idea that offshore 

waters provide a migration corridor for post-breeding eiders. However, given the “snapshot” nature of this 

survey, it is difficult to predict timing or routes of migrating birds. Distribution patterns were documented 

for an additional 6 marine bird taxa in offshore waters. 

STUDY PRODUCT(S): Fischer, J. B., T. J. Tiplady, and W. W. Larned. 2002. Monitoring Beaufort Sea 

waterfowl and marine birds, aerial survey component. A final report by the U. S. Fish and Wildlife 

Service, Division of Migratory Bird Management, subcontracted by the Alaska Science Center (USGSBRD) for the U.S. Department of Interior, Minerals Management Service, Alaska OCS Region, 

Anchorage, AK. NTIS No. PB2002-102377. Intra-agency Agreement 16950. 146 pp. 

* P.I.’s affiliation may be different than that listed for Project Manager(s).
Technical Summary Figure 1. Study area for Near-shore and Offshore marine bird surve

Alaska, 1999-2000.