Grass
Grass is one of the primary nesting materials northern pintails use to make nests. Grass is readily available due to the short vegetation in typical nesting sites.
Twigs
Like grasses, twigs are readily available near the nesting sites and are used as part of the nest building. Twigs are a less common material than grasses.
Down
Northern pintail females line the nest with down feathers. The feather lining helps in the incubation process. Females lay eggs during the start of winter and the down lining helps keep the eggs warm during the incubation period of 21 days.
Note on Nest
The northern pintail nest is one of the most exposed nests made by ducks. The nest is built on a shallow depression in the ground, leaving it mostly above the ground where predators are able to get into the nest and steal eggs.