How is nesting success research conducted?
Nesting Success Research
In order to refine our understanding of factors influencing duck nesting success, DU researchers first have to obtain a sample of duck nests across the areas where we are interested in delivering conservation programs. Fortunately, in the late-60’s some pioneering waterfowl biologists at Northern Prairie Wildlife Research Center developed a field method for obtaining large numbers of duck nests. This ingenious method used a length of cables and chains stretched between two vehicles to systematically locate nests within grasslands (Techniques for Studying Nest Success). As the vehicles drive parallel to one another across a field of grassland, the chain lays over the grassland while riding several inches above the ground. When the chain passes over a nesting female duck, the noise and disturbance of the moving grass causes her to flush from her nest, thus revealing the location of her nest.
Once the nest is located, a number of important attributes of the nest are recorded. The species of duck and the number of eggs in the nest are recorded. Next, the development stage of the eggs can be determined via a method called candling. The egg shells of duck eggs are translucent and by holding the egg at the end of a 6” piece of radiator hose the stage of incubation can be determined. This allows DU’s researchers to determine when the nest was initiated and how many days remain before the nest will hatch. Ducks lay one egg per day and then the duration of incubation results in a predictable level of development of the ducklings until ultimately the eggs hatch.
Additionally, a suite of habitat characteristics is recorded at each nest. The habitat type the nest is located in is recorded. A special Robel pole, a plastic electric fencing stake divided into decimeter increments, is used to measure the height and density of vegetation at the nest site itself. A Global Positioning System (GPS) recorder is then used to take a very precise location of the nest. Finally, satellite imagery is acquired for the region surrounding each research site in order to identify the amount and spatial configuration of landscape scale habitat factors such as the amount of grassland, amount of edge between cropland and grassland, acres of flooded wetland habitat among others. The nest is then inconspicuously marked so the researchers can revisit the nest every 4-5 days to determine whether the nest remains active, has hatched or has been destroyed.