3.4 Marine Boat Offshore Islands Surveys (Harlequin Ducks)

Recommendations: Marine boat surveys of offshore islands are recommended at the local and management unit scales: to determine presence and estimate relative and absolute abundance of harlequins during the moulting and wintering periods. Since birds will likely be missed, absolute estimates will likely be underestimated.

Boat surveys are relatively inexpensive and are an effective means of surveying harlequins on marine coasts. Small boats can circle rocky islets and follow coastlines close to shore. Observers count birds as they are encountered. If appropriate distance is maintained then accurate identification, sexing, aging and counts are possible with little disturbance to the birds. Zweifelhofer (1994) surveyed nearly 1,000 km of shoreline on Kodiak Island, Alaska by this method and found that sex/age ratios can be determined during the wintering period. This method is suitable for relative and absolute abundance estimates, although it tends to underestimate true population size (see Mittelhauser 1994).

Advantages

• Allows careful searching of potential habitat because of maneuverability of boats.
• Allows accurate observation, counting, and identification of cryptic species like harlequins.
• Can determine sex ratios in flocks.
• Can monitor productivity based on age/sex determination from plumages.
• Can survey remote sites not accessible by land.
• Relatively cost-effective compared to aerial surveys.
• Colour-banded birds are detectable.
• Can cover large geographic areas in relatively short periods of time.

Disadvantages

• Suitable only for harlequins.
• Probably results in underestimates of populations.
• Need more specialized equipment than for land-based surveys.
• Need trained personnel capable of handling boats and working in remote coastal settings.
• Very dependent on sea and weather conditions.

Office Procedures

• Review the section, Conducting a Wildlife Inventory, in the manual Species Inventory Fundamentals (No. 1).
• Obtain relevant maps for project area (e.g. Nautical charts, 1:50 000 air photo maps, 1:20 000 forest cover maps, 1:20 000 TRIM maps, 1:50 000 NTS topographic maps).
• Determine Biogeoclimatic zones and subzones, Ecoregion, Ecosection, and Broad Ecosystem Units for project and study areas from maps.
• Select study areas from 1:20,000 or 1:50,000 maps using marine charts, personal experience and existing data.
• Plan the survey route to maximize efficiency in travelling and covering all habitat.
• Survey lines are transects which follow the shoreline along the coast and are drawn on maps used for navigation.
• Organize rental of boats and availability of personnel.
• Provide training for personnel on boating safety, and survey techniques.
• Prior to the survey, personnel should meet to standardize recording. Team members should review maps of the area.

Sampling Design

• Systematic. Islands are circled by boat. Island shorelines are considered to be circular transects which may be further broken into segments.

Sampling Effort

• The time required varies with the area to be surveyed, the travel time to and from the survey area, and the speed of the watercraft.

Personnel

• The survey crews (2-4 people) should be led by a Registered Professional Biologist, or experienced waterfowl biologist, with experience in marine bird surveys.
• All crew members should have a high tolerance for motion sickness.

Equipment

• A suitable boat for surveying near shore marine waters. A smaller boat or inflatable is preferred to enable maneuvering between small offshore islets.
• Marine charts and Global Positioning System for noting location of survey sites.
• Waterproof notebooks, data forms and mechanical pencils.
• Each observer should have 7-8X wide-angle binoculars.
• Appropriate safety equipment (life jackets or survival suits, flares, HF radio, spare fuel, emergency rations, etc.).

Field Procedures

• Surveys should be scheduled for fair weather days with wind speeds less than 25 km/hr.
• Surveys should be scheduled to coincide with peaks in moulting and wintering abundance.
• Survey routes should be marked on maps. Individual islets within island groups have to be clearly numbered on the maps.
• Islands are circled by boat, at a speed that allows observers to detect any birds present. The observers scan the shorelines for birds. The boat may be stopped to enable better identification and counting.
• All harlequins present should be detected. Age and sex classes of the birds should be noted, and behaviour if time permits.
• Hauled out harlequins should be checked for tarsal coloured bands if time permits.
• The data should be recorded in waterproof note books/data forms with pencils. Note: if note books are used, data must later be transcribed onto the provincial standard data forms.

Data Analysis

• Data may be displayed and analyzed as in Aerial Surveys.