Waterfowl

Reports

Expanded Aerial Surveys of Waterfowl in Alaska

Several wetland areas in Alaska have been surveyed more intensively than by the North American Breeding Pair Survey. These expanded breeding pair surveys were designed to determine if the original survey was adequately predicting waterfowl numbers. In addition, these expanded surveys allowed mapping of waterfowl distribution using new technologies. We began using a computerized geographic information system (GIS) in 1988 to display and analyze our waterfowl data. Originally, survey flightlines were drawn by hand on maps and the crews went out and flew the surveys without any of the modern navigation equipment. Waterfowl observations were recorded on portable tape recorders during the surveys. The flightlines were generally about 16 miles long and there was no way to keep track of where the waterfowl were located along the flightline.

A simple but clever innovation was developed in the mid-1980's that allowed us to pinpoint the location of every bird observation along the flightline. The trick was to turn on the tape recorder, record the start of the flightline, keep the recorder running, record each bird observation and finally, record the end of the flightline. Then, back in the office, the tape was replayed while using a computer data entry program. This program used the computer's clock like a stopwatch to determine the elapsed time to each waterfowl observation and the total elapsed time to fly the entire flightline. This ratio was equal to the ratio of distance from the start of the flightline to the total length of the flightline. For example, if it took 10 minutes to fly the entire flightline and a mallard was seen 5 minutes from the start, then the mallard would be located halfway along the length of the transect. We then calculated the latitude longitude coordinate of the observation based on the distance from the known start point. Knowing the precise location of every bird observed on our surveys opened up exciting new possibilities for analyzing waterfowl populations.

However, the use of tape recorders and this technique required long hours of transcribing the data. A significant breakthrough was achieved in 1996 by John Hodges, pilot/biologist/programmer with the Juneau field station of the Waterfowl Branch. He created two Visual BASIC programs to record and transcribe aerial observations substituting a portable computer for the tape recorder. This portable computer connected with the aircraft global positioning system (GPS) receiver and a remote microphone and mouse. The observer recorded transect numbers, segment numbers, segment start and stop points, cardinal direction of the start end of the segment, and bird observations out to 200 meters directly into the computer to a .WAV format sound file using the remote microphone and mouse. Birds observed were identified to species and counted as a single, pair, or number in flock. Simultaneously, latitude/longitude coordinates for each observation were automatically downloaded from the GPS to a text file. A data transcription program was used to replay the sound files, enter header information, species codes, group sizes and combine these with the coordinate information to produce a final data file. The program also recorded a text file of the entire aircraft flightpath during the survey. The program also displayed the aircraft track on a topographic map on the computer screen to allow the crew to monitor their progress. This new system has greatly increased the efficiency of data collection on aerial surveys.

Expanded breeding pair surveys have been conducted on the following areas for the years listed: (Hotlinked items contain reports for the surveys in pdf format)

Last Updated: September 15, 2008