Effectiveness of Vehicle-towed Nest Drags at Finding Duck Nests

Abstract

Effective wildlife management depends on the assumption that the research techniques employed are scientifically and ecologically sound. In the management of popular waterfowl species, like dabbling ducks, nest density and success are often assessed using a vehicle-towed nest drag. This technique involves systematically searching a treeless, herbaceous habitat using two vehicles such as jeeps or ATVs with a heavy cable and chain, or just a chain, stretched between them. The nest drag passes over the vegetation where ducks nest, causing females to flush from the disturbance. Their nests can then be marked and revisited to collect data on nesting densities and reproductive success, and consequently used to devise appropriate management schemes. By analyzing data collected in habitats owned by Ducks Unlimited Canada, I evaluated the effectiveness of vehicle-towed nest drags at finding duck nests using the specialized population estimation software program DISTANCE. Specifically, I tested if nest detection was influenced by the distance from the towing vehicles, nest age, and duck species. My research provides “correction factors” that allow investigators to estimate the proportion of nests that are missed during regular surveys for waterfowl nests.