Absolute Abundance for breeding pair counts / brood counts for the most conspicuous species (e.g., loons, geese, swans) and when necessary for dabbling ducks in large, inaccessible areas.
Detection of birds from the air is relatively poor and counts are inaccurate except for large conspicuous birds at medium densities, e.g., breeding swans and geese. Therefore, air surveys are suitable for absolute abundance estimates for these species only. Counts from helicopters are much more accurate than those from fixed-wing aircraft. Surveys from fixed wing aircraft should not be used to collect data to estimate indices of absolute abundance. Estimates are very sensitive to transect width, altitude, glare and flight speed therefore it is important to conduct surveys consistently.
This technique is also used for relative abundance surveys. Only differences from the relative abundance survey are listed here. For details on how to conduct this type of survey see section 3.4.3.
Total count for each Study Area or wetland:
Example: Nixon and Majiski (1991) conducted breeding pair surveys in boreal forest wetlands with low waterfowl densities in the Liard Plain and Teslin River Basin. Wetlands were stratified on 1:50,000 topographical maps into three size classes (<1.5 hectares, 1.5-15 hectares and 15-300 hectares). Larger lakes were excluded because it was not feasible to obtain an accurate count. A sample of wetlands within each size class was chosen randomly but most distant wetlands were omitted due to limited time available for the survey. Observers sampled each wetland by circling it in a helicopter. The helicopter would hover while they recorded the number of birds and wetland characteristics. Counts at each wetland were repeated four times at six day intervals starting in mid- to late- May to ensure an accurate estimate of the number of breeding pairs (McKelvey 1989). The mean number of breeding pairs for each species was calculated using the four repeated surveys for each wetland. The density of breeding pairs was calculated from stratified samples. The results were used to estimate the population of breeding pairs within the entire Liard Plain and Teslin River Basin region. Stratifying by wetland size did not increase the precision of the population estimates because the sample sizes were too small (9 to 30 in each strata). It may have been better to survey more wetlands in each strata and do fewer replicate counts at each wetland.