Accession Number : ADA322804
Title : Aerial Surveys of Waterbirds in Alaska 1957-94: Population Trends and Observer Variability,
Corporate Author : FISH AND WILDLIFE SERVICE JUNEAU AK
Personal Author(s) : Hodges, John I. ; King, James G. ; Conant, Bruce ; Hanson, Henry A.
PDF Url : ADA322804
Report Date : AUG 1996
Pagination or Media Count : 32
Abstract : Since 1957, major breeding populations of ducks in Alaska have been consistently monitored with strip-transect sampling from aircraft. By 1964, most other large waterbird species had been added to the survey. From 1957 to 1994, the population sizes of dabbling ducks generally remained stable. The populations of diving ducks and sea ducks except those of the merganser and the canvasback declined by 15-75% during 1976-94. The population sizes of eiders declined by 90% since 1957. We have also determined and present here the population distributions of all species and the population-size trends of loons, geese, swans and cranes. Improved survey conditions with a change of aircraft type in 1977 allowed us to count more birds.
Descriptors : *WATERFOWL, *AERIAL SURVEYS, AIRCRAFT, ALASKA, POPULATION, VARIATIONS, SAMPLING, PATTERNS, CRANES, DIVING, CENSUS, BREEDING, DUCKS, GEESE, SWANS.
Subject Categories : Ecology
Distribution Statement : APPROVED FOR PUBLIC RELEASE