Field Procedures - Aerial

Breeding (swans & geese) and Non-breeding Bird Counts

• Do not survey more than seven hours per day and take breaks to avoid observer fatigue.
• Mark airplane struts at measured distance from the body of the plane to ensure sampling the intended strip width. Use two markers, to account for the range of heights you are likely to fly. For ocean coastline surveys, where the objective is to record all birds in littoral waters (which can vary in width), a transect width is not required.
• Recommended strip width is between 50 and 100 m on each side of the aircraft with one observer seated on each side.
• Fly transects at 135-180 km/h (70-90 knots) approximately 30 to 50 m (100-150 feet) above ground or water. Over open water with low bird densities (e.g. marine habitats), the higher speeds enable more area coverage.
• Record using tape-recorders the numbers of birds flown over within the fixed-width.
• Record species and numbers, and where possible characteristics of birds (e.g., age, sex, plumage, behaviour, group size).
• Transfer data to dataforms immediately after survey is finished.

Data Entry

• The Design Component for this survey is transects. When digitally entering the survey data, choose `Transect' from the `Design Component Type' picklist.

Data Analysis

• Calculate mean counts for replicate transects (where replicates are possible). Precision is calculated as the square root of the variance around the mean for replicate transects within each strata.
• Relative abundance can be expressed as:
• Total estimated counts: total number of birds in all the transect sections within a certain location are summed together to give the relative abundance of birds in an area at a given time.
• Birds in an area: Birds/km² (divide the number of birds observed by the area surveyed in transect of fixed length and width)
• Birds per kilometre of survey route (Birds/km)
• Long term annual trends may be analyzed using route-regression analysis (Geissler and Noon 1981, Dickson 1989) although further research may reveal a more appropriate method (Thomas pers. comm.).
• The following strategies should be used if the data are to be used for monitoring of trends:
• Surveys should be replicated on sequential mornings as discussed previously. This data should be used for power analysis to ensure that sample sizes are adequate to document hypothesized population trends or compare hypothesized differences between areas. See Species Inventory Fundamentals manual (Appendix G) for more details on power analysis. In addition standard errors, and coefficients of variation for relative abundance measures should be reported to allow evaluation of the repeatability of measurements.
• It can be argued that non-replicated transects do not give that much information about the target populations for it is impossible to separate sampling variance from actual variance in population size due to actual biological trends.
• The analysis of count data requires specialized statistical techniques. See Species Inventory Fundamentals manual (Section 5.3) for more details.

3.4.5 Call Playback

Relative Abundance for Pied-billed Grebes, coots and other birds that vocalize during the courtship or territorial phase of breeding.

Call playbacks are suitable for detecting secretive breeding species like Pied-billed Grebes (Gibbs and Melvin 1993) which call to establish and defend territories and attract mates. A call playback mimics the presence of an intruder in the territory and results in a vocal or visual display. Relative abundance can be determined if surveys are conducted using a consistent method (consistent bias) and frequently enough to ensure precision. Call playbacks can improve the efficiency and accuracy of nest counts. They are unlikely to work at times of the year when birds are not territorial.

Advantages:

• Improves accuracy in counting secretive birds (Gibbs and Melvin 1993).

Disadvantages:

• Time consuming;
• May disturb birds;
• Many species do not respond to calls;
• The relationship between the number of calling or responding birds and the actual breeding population is unknown;
• Call playback does not sufficiently sample females or young in a population, therefore it only provides an index of a breeding population; and
• The use of tapes and broadcast equipment introduces an additional source of variation (i.e., in addition to observers, weather etc.).

Office Procedures

• Review the introductory manual No. 1 Species Inventory Fundamentals.
• Obtain relevant maps of the project area (e.g., 1:50 000 air photo maps, 1:20 000 forest cover maps, 1:20 000 TRIM maps, 1:50 000 NTS topographic maps). Any map which is used to record data should be referenced to NAD83.
• Outline the Project Area on a map and determine Biogeoclimatic zones and subzones, Ecoregion, Ecosection, and Broad Ecosystem Units for the Project Area from maps.
• Delineate on topographic maps or air photos one to many Study Areas within this Project Area. Study Areas should be representative of the Project Area if conclusions are to be made about the Project Area. Generally, a Study Area will be equivalent to a single wetland. Generally, establish Study Areas by stratifying habitat based on expected bird densities (e.g., low, medium, high). Eliminate habitats which are not feasible to survey from the ground (e.g., large lakes).
• Select wetlands from the strata.
• Identify shortest routes between samples (wetlands).
• For each Study Area:
• Determine Biogeoclimatic zones and subzones, Ecoregion, Ecosection, and Broad Ecosystem Units for areas surrounding the wetland. Determine wetland type using the Riparian Management Area Guidebook (B.C. Min. Environ. and For. Serv. 1995) as a general reference.
• Identify access points and potential call playback stations for surveys from large scale, colour aerial photographs.
• Prepare a survey tape of the target species' calls.
• Tapes should include, for each species, three series of 20 seconds of calls (c) followed by 30 seconds of silence (s), (except after the last call in a sequence, which should have one minute of silence before the next species), [sequence 20(c1)-30(s1)-20(c1)-30(s1)-20(c1)-60(s1)-20(c2)-30(s2)-etc.]. Each species can be recorded consecutively on one tape. (If you are recording from a commercial CD or tape, do not include the announcement of the species!)
• For comparable results, broadcast tapes should be identical in terms of duration, sequence and quality of calls. Some birds will reply to calls of other species, as well as conspecifics, and so whether they are first or last on the tape will influence the duration of time available for a response. Although it has not been well explored, it is also possible that loud calls may suppress calling of quieter species. It is probably best to be conservative and play calls from quietest species to loudest.
• Tapes degrade with exposure and should be replaced at least once per field season.
• Test the call playback equipment to ensure that it works (see Call Playback Equipment section below). Measure the distance that sounds will be broadcast to determine the area that can be sampled from each broadcast point.