An interesting avian phenomenon is happening right now in a sky near you. It happens every year around the end of May and into June. That is, large numbers of boisterous Canada geese are migrating northerly.
This fascinating spectacle is a curiosity to many observers since it seems to defy what we think we know about the fundamentals of bird migration, particularly where timing is involved. So why are Canada geese flying north in June when, clearly, active nesting has been underway for some time and goslings are a very long way from fledging?
These geese, these flocking geese that are heading north, are on their way to northerly water bodies where they can spend a month or more in order to molt. Canada geese and other waterfowl typically are unable to fly during their annual molts when tail and flight feathers molt, so migrating to protective places is paramount.
Molt migrants — as these Canada geese are called — are predominantly non-breeding adults or adults that have had failed nest attempts, along with other stragglers that don’t have offspring to care for. These geese leave breeding territories behind in order to find seclusion and a place to molt. It’s a wonder of nature, to be sure.
Flocking in general is an interesting subject to think about. First off, flocking reduces the risk of being preyed upon, as well as permitting birds to forage together in cooperative ways. Regarding the former, “safety in numbers” is what it’s all about.
That birds-of-a-feather flock together also makes it difficult, not to mention dangerous, for birds of prey such as falcons to successfully capture and kill an individual bird within a flock. A raptor preying on flocked birds risks serious injury or death if it attempts to enter the middle of a large, tightly packed flying flock of starlings or other similarly behaving birds. A high-speed, mid-air collision could easily occur if the raptor is unable to react in time if one or more of the panicked birds enter into its flight path.
Flocks create “predator confusion,” as it is called, for predators. And this phenomenon can also happen with human predators. A classic example occurs in the duck blind. Waterfowl hunters, for instance, are taught from an early age that in order to shoot and kill an individual duck or goose amongst a flock, one needs to learn how to concentrate on a single bird while simultaneously ignoring the others. It is no different for an avian hunter, like a merlin, as it attempts to zero in on a lone bird flying at the outskirts of a flock or lagging behind.
Gathering in groups also benefits birds through cooperative feeding behaviors. A good example of this occurs in the feeding style of American white pelicans. These birds commonly swim together in order to drive small fishes into shallow water where capturing them is easier.
Other birds, like black-capped chickadees and waxwings, frequently forage together in loose flocks. The birds are constantly communicating to one another as they flit from branch to branch searching for insects, seeds, and, in the case of waxwings, fruit. Individual birds that happen to locate abundant food sources are quickly noticed by other nearby birds and, thus, serve as a boon to other members of the flock.
Additionally, migrating, flocking birds don’t always occur during daylight hours. In fact, the opposite is generally the case. Most songbirds migrate at night, as do many other species of birds. So put it on your calendars for next March through May when songbird migration is underway and at its peak to grab your binoculars and head outside.
Pick a clear night when the moon is big, bright, and full. If you’ve never done this, you’ll be pleasantly surprised at what you’ll likely see if you catch the migration just right. While peering through your optics at the moon, you’ll see silhouettes of scores of flocked birds flying across the face of the moon and your binocular’s lenses.
Flocking together is survival for most birds. The more there are, the more eyes to notice potential threats and available food sources. Indeed, observing so many birds all at once — like molt migrant Canada geese flocking north right now — is a marvel worth viewing as we get out and enjoy the great outdoors.