The Nebraska Sandhills are an important area for breeding ducks in the Great Plains, but reliable estimates of breeding populations are unavailable. Double-observer methodology was used to estimate abundance of breeding duck populations in the Nebraska Sandhills. Aerial transect surveys were conducted using methodology similar to the cooperative Waterfowl Breeding Population and Habitat Survey conducted by the U.S. Fish and Wildlife Service and Canadian Wildlife Service. Observations by two front-seat observers and one rear-seat observer were used to account for incomplete detectability. Transect-specific population size and detection probabilities were estimated using program SURVIV; estimates were species-specific by type of social grouping. Regional population sizes were obtained by extrapolating transects' estimates to the Sandhills. Detection probabilities were high (>0.75) for all species, but highest for Northern Shoveler (Anas clypeata) and Gadwall (A. strepera). Detection probabilities generally followed increases or decreases with duck densities. Uncorrected population estimates, on average, were <7% the population estimates obtained by correcting for detectability. Double-observer methodology should be considered for adjusting duck counts that cannot be corrected using additional aerial or ground surveys, particularly where water and ducks are well dispersed.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.