This is probably one of the hardest areas for me personally when it comes to wildlife photography. Waterfowl can be really frustrating subjects as they have the tendency to move a lot. When there is activity on the shoreline they will instantly b line away from said activity to somewhere safer. This is often why photographers go out in blinds or setup somewhere and wait a really long time. One piece of advice when it comes to waterfowl is to not chase the birds. Trying to outmaneuver any duck will just end up with you scaring the bird off completely. If you don’t have or want to use a blind then arrive early and wait patiently. It might seem like common sense and that’s because it is. Those lessons tend to work well with photography.
Now I know from personal experience that chasing the subject doesn’t work as this Harlequin Duck is a perfect example. It’s a little early for them to be nesting in the area but they serve my purpose. These guys brave the rapids of the fast moving rivers and often nest in Yellowstone. Trying to keep up with them is a challenge and not exactly safe. But spending time watching them and seeing where they go will keep you and them safe.