Have you ever noticed huge flocks of black birds swarming into your region during the fall and winter? Chances are, these birds are grackles migrating to their winter homes further south. So, when do grackles migrate, exactly? What are their migration habits? Keep reading! In this article, we’ll answer these and other questions related to grackle migration.
What You'll Learn Today
What Time of Year Do Grackles Migrate?
Grackles typically migrate during the late fall and early winter months when heading south; the season tends to peak around October and November most years. In the early spring, around February and March, they begin heading back north.
The exact time of migration may depend somewhat on weather patterns and changes from year to year, as grackle flocks may begin their migration later or earlier depending on the weather. They are fairly consistent in their timing if there are no extreme weather pattern shifts.
Grackles are not nocturnal, so they tend to travel by day while roosting in large flocks by night. They are very social birds, particularly during the migratory season, as they tend to do everything within the confines of the flock–hundreds of thousands of birds spend their winters together, eating, sleeping, and traveling as a group.
Do Grackles Always Migrate?
In most areas of the U.S. and southern Canada, grackles are known as short-distance migrants. This means that they do migrate, but they typically don’t go very far from home.
And even then, not all grackles migrate.
According to the Virtual Nature Trail at Penn State New Kensington, those grackles found in southern areas tend to stay in their home regions year round. There is no need to migrate as long as there’s an abundance of food and the temperatures don’t drop to extremes.
Even the grackles living in northern regions often migrate just far enough south to avoid the most extreme winter conditions. For example, grackles found in the northern U.S. and southern Canada may only migrate as far south as the Great Plains and southern Midwest regions of the U.S.
Because they don’t migrate very far, their overwintering homes often still receive a lot of snow and cold, which in turn can lead to grackles having a more restricted diet during the winter. While they typically eat lots of insects during warmer weather, they have to rely largely on plant matter such as seeds and grains during the winter.
How Do Grackles Migrate?
As noted above, grackles do not migrate alone. They travel in large groups, during daylight hours.
The large flocks of grackles can make for an impressive sight, as you can see from the video below.
As mentioned, grackles travel relatively short distances compared with other bird species, often selecting their winter home long before they’ve left the colder northern regions. Sometimes even those in the north opt to stay put and band together with other types of blackbirds.
Whether they migrate or not, grackles always band together in large flocks during the winter. Why they choose to flock isn’t exactly certain, though it may have something to do with trying to stay warm or seeking safety in numbers.
Other Grackle Migration Habits
Migrating and overwintering grackles are a common sight in the central and southern U.S. during the winter. Some of the behaviors you may observe include:
All winter long, grackles will remain in their flocks. A single flock can contain up to a million birds, though some flocks are much smaller. It isn’t uncommon to see large “clouds” of grackles moving south in late fall and back north again in early spring.
In early spring especially, as mating season nears, male grackles in a flock will begin to think about pairing up with females. The first part of this is establishing dominance over other males, usually by participating in a peaceful competition known as “bill tilt.”
Once the dominant males have been established, they will begin to choose their mates. Females are most likely to choose dominant males, so the dominant ones generally have their choice among the available females.
While in the process of migrating, it isn’t uncommon for an entire flock to land in a harvested field to forage loose grain and insects. If you live in the path of their migration, you may even find them taking over your own backyard as they pass through.
Just as they feed together, migrating flocks of grackles also sleep together. You’ve probably seen power lines and billboards lined with black birds sitting shoulder to shoulder at dusk or after.
The birds most likely roost in groups for safety purposes.
Grackles who live in northern regions migrate south during late fall and early winter, returning home again in the early spring months. Grackles who live farther south do not migrate but stay in their native regions year round.
Regardless of whether they migrate or not, grackles gather together in flocks for the winter. These flocks eat, roost, and travel together throughout the winter months.