Waterfowl
Reports
Yukon
Delta Aerial Breeding Waterfowl Survey
Aerial surveys of geese nesting
in the coastal zone of the Yukon-Kuskokwim delta have been conducted each spring
since 1985. The objective of the project was to develop aerial survey procedures
that provided an annual index to the number of breeding pairs of cackling geese (Branta hutchinsii), emperor geese (Chen canagica)
and greater white-fronted geese (Anser albifrons). Since 1988, others species
of birds such as ducks, loons, and gulls have also been recorded by an observer
in the back seat. Another objective was to obtain information on the distribution
of the birds on the nesting grounds.
The survey was based on a systematic
random design. Strip transects 400 meters wide were systematically spaced at 1,
2, 4 or 8 mile intervals from a random start point. Greater survey effort was
allocated in areas known to support more geese. These transects extended from
the coastline inland to the edge of upland tundra. The transects sampled a survey
area that included land from Norton Sound in the north to the mouth of the Kuskokwim
River in the south.
Transects were flown following conventions established
for breeding ground surveys in North America. A Cessna 206 amphibious aircraft
was flown at 85-95 mph and at altitudes of 100-150 feet. A Loran-C and in later
years a Global Positioning System was used to navigate the transects. Surveys
were flown only in good weather. The pilot and observer in the right seat recorded
singles, pairs and flocks of cacklers, emperors, white-fronts, and tundra swans
observed in a 1/8 mile strip on each side of the aircraft. An observer in the
back seat recorded other species such as ducks, loons, gulls, terns, and grebes.
These observations, as well as the start and stop of each transect were recorded
on notebook computers connected with the aircraft global positioning system (GPS)
receiver and a remote microphone and mouse.
Survey observations were
transcribed and data entered into a computer. Population indices for each species
have been calculated for each year and population trends over time have also been
calculated. Geographic distributions of the species have been mapped using geographic
information system software. This information is used by managers when making
decisions that may affect waterfowl populations. For the Summary Report of data
collected by the back seat observer click on the following link:
Abundance and Trends of Waterbirds on Alaska's Yukon Kuskokwim Delta Coast based on 1988 to
2009 Aerial Surveys. (14mb - pdf)
Last Updated: October 16, 2009
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