To identify distant waterbirds, learn their flocking behavior

In much of the country, winter birding involves scanning the open waters for ducks, loons, cormorants and anything else that might be found there. The birds we find are often far apart and identifying them is a challenge not because the species are similar, but because they are too far apart to see details. In these situations, any clue to disentangle the possibilities can be helpful. We all naturally seek color, and even very general impressions of light and dark are valuable. (For example, cormorants almost always have a blackish appearance.) Habits like diving are important clues, and general shape – length of neck, prominence of wing or tail tips, etc. – is also useful.

Another usually overlooked clue is herd behavior. In the same way that flocking behavior varies among songbirds, it also consistently differs between waterfowl species. Some species often form large, dense groups, while others only occasionally congregate in small, loose groups. Geese organize themselves in different patterns than ducks, and flocks of mallards differ from flocks of pochards, for example.

Before beginning to observe flocks, it is important to distinguish between foraging behavior and resting behavior. Typically, in waterbirds, foraging birds disperse more widely and roosting birds congregate in tighter groups. For example, many species (loons, most grebes, pelagic cormorants, puffins) are solitary when feeding, but these same species form loose groups when resting on the water. Ducks are more scattered when feeding, but crowded together, often in large groups, when resting. And of course, groupings are also influenced by food and local conditions.

Given all these variations, it might seem pointless to try to describe the differences in flocking behavior, but it can really be helpful. It is not a standalone land mark. You will rarely be able to identify a species simply by herding behavior. But in addition to general color, size, and habitat, flock characteristics can help you identify some far-flung birds. It’s one of the cues experienced birders use, even subconsciously, to quickly sort out distant birds. You can begin to learn these differences simply by noticing the behavior of birds in your local patch, and soon you will be more easily identifying distant waterbirds.

Eldon Greij: The Value of Herds