3.4 Ground-based Surveys of Wetlands and Waterways

Recommended uses: This method is used at all 3 levels of inventory intensity depending on species and season. See Table 2 for species-specific recommendations.

Presence/Not detected

Recommended for presence/not detected studies in areas with land-based access because of low-cost and logistical ease.

Relative abundance

Recommended for relative abundance estimates on wetlands and marine waters where birds are visible through binoculars or spotting scopes.

Absolute abundance

Recommended for absolute abundance estimates of breeding colonies on ponds and small lakes without extensive emergent cover, and for nonbreeding populations on nearshore marine waters and staging populations on large inland lakes.

When used in support of nest counts, this method can improve estimates of breeding populations of grebes. It is very useful for inventory of herons at prime foraging sites, where they gather in large numbers (e.g., Roberts Bank).

Ground-based surveys have been widely used to inventory breeding and wintering grebes, populations of Great Blue Herons at foraging areas, and long-range inventory of breeding and foraging flocks of American White Pelicans (Ryder 1973; Breault et al. 1988; Butler 1989; Butler and Cannings 1989; Savard 1991; Searing and Cooper 1992). Birds are observed by spotting scope and/or binoculars from observation points. If the whole study area can be readily observed, a fairly accurate count of birds on individual wetlands and waterways can be obtained. However, surveys are restricted to areas with land-based access.

For grebes, during the early breeding season, counts of breeding pairs can be made. Although not useful for inventory of active nests of grebes and pelicans, it is a suitable method for counting broods of grebes after young have left the nest. Counting broods is a widely-used technique for assessing reproductive success in specific wetlands, and provides a minimum value for numbers of breeding pairs in specific locations (Savard 1991). Mixing of older broods can be extremely confusing, however, especially in marshes with large numbers of breeding pairs (e.g., Eared Grebes). Great Blue Herons can be counted from a distance as they fly to and from nests while feeding nestlings (Forbes 1986). Numbers of breeding pairs can be estimated, when nestlings are 5-8 weeks old and parents spend little time brooding, by counting birds as they leave to feed around dawn.

One major advantage of this method is that surveys can be conducted slowly, and repeat counts can be made to improve estimates of numbers. This is especially helpful for grebes which may be diving, or for large flocks of foraging Great Blue Herons that often move around in short up-and-down flights as they follow flooding or ebbing tide lines. Additional advantages are that survey "teams" can consist of one person, and trained amateur naturalists can easily participate, thus increasing cost-effectiveness.

Data can provide reliable estimates of presence/not detected and relative abundance. Estimates of absolute abundance may require repeated surveys to account for variability in presence or visibility of birds. For example, Great Blue Herons gather at key foraging sites during the breeding season, but only part of the adult population will be present during the incubation and early nestling periods. After nestlings require less brooding, both parents may leave the nest and higher counts will result.

Office Procedures

• Review the section, Conducting a Wildlife Inventory, in the introductory manual Species Inventory Fundamentals (No. 1).
• Obtain any necessary permissions for access to survey areas (private land-owners when private property must be crossed to reach a wetland or observation point).
• Select study areas from 1:20 000 or 1:50 000 maps based on personal experience, and existing data. Existing data are available to locate colonies or wintering concentration sites (see B.C. Nest Records Scheme, or Campbell et al. (1990). Check with regional Ministry of Environment biologists or local naturalists if current status of specific sites is in doubt.
• Determine Biogeoclimatic zones and subzones, Ecoregion, Ecosection, and Broad Ecosystem Units for census areas from maps.

Sampling Design

• Systematic. Travel along selected wetlands and waterways, stopping at viewpoints (observation stations) where birds are easily visible. Ensure that all possible habitats are covered.

Sampling Effort

• A survey party can probably cover 0.5 to 1.5 kilometers per hour of wetland shoreline, depending on density and complexity of distribution and abundance of target species.
• Surveys should be repeated more than once during the season.
• Estimates of absolute abundance may require several repeated surveys to account for variability in presence or visibility of birds.
• Western Grebes - Annual monitoring is recommended for breeding and wintering populations.
• Red-necked/Eared Grebes - Major colonies should be surveyed every 3-5 years.
• Great Blue Heron - Annual monitoring is recommended.

Sampling Standards

Time of day

• The time of day and tidal cycle can affect bird distribution. For example, Great Blue Herons forage on open intertidal habitats during low and mid tidal cycles where they are very visible but disperse to upland roosting areas, or back to their colonies when the tide is in (Butler 1991). American White Pelicans leave for foraging lakes in mid-morning and, although some birds may stay away overnight, counts are best made in the early morning (Dunbar 1984).

Vantage point

• Emergent vegetation on breeding or staging wetlands can obscure birds from view, especially grebes. This problem intensifies as the season progresses and vegetation grows taller and thicker. Vantage points with clear views of the study area are critical to obtaining reliable estimates.

Distance

• Birds beyond the range of a spotting scope will be missed (large lakes and marine habitat). Variable 20-45X scopes are commonly used and 45X is a normal maximum power because of blurring caused by heat waves and/or wind. Distances at which birds are detectable vary with species. With bright light and low wind, herons and pelicans can be identified and counted up to about 1.5 km, Western Grebes to about 1 km, Red-necked Grebes to about 500 m, and Eared Grebes to about 300 m.

Weather

• Surveys should not be conducted if the wind speed is over 30 km/hr, during heavy or moderate rain, or during periods of snow or fog.

Personnel

• The survey crew can be as small as one person (although safety considerations may preclude this possibility). Additional personnel can increase the number or area of wetlands surveyed per day.
• All crew members should have excellent waterbird identification skills. The crew leader should be an experienced biologist.

Equipment

• A suitable vehicle is needed which provides good visibility to the surrounding countryside for roadside viewpoints. Ideally, the vehicle will ride high enough above the road surface so that vision will not be hindered by roadside bushes.
• In most cases, a 4WD vehicle may be advisable to access wetlands.
• Each observer must have a pair of 7-10X binoculars and each team should have a spotting scope ³20X.

Field Procedures

• Travel to/along selected wetlands and waterways, and scan for target species from view points. Ensure that all possible habitats are searched. If certain areas are inaccessible or cannot be surveyed, note their locations and the extent of area not searched.
• Mark view points on maps and relate position of each bird recorded to view point.
• Complete enclosed dataforms.

Data Analysis

• Relative and absolute abundance estimates can be made by determining total counts for specific wetlands, by calculating numbers of birds per unit area, or numbers of birds per km of shoreline.
• Data can be displayed as:
• distribution maps:
• maps for each species, or combined for all species,
• maps for relative abundance (i.e., different sized circles for various group sizes),
• maps showing occurrence in relationship to habitat, ecoprovince, biogeoclimatic zone, etc.,
• tables comparing total counts of individual wetlands.
• tables comparing presence/not detected in different surveys, temporally or in distribution.