Migration Station

As millions of our feathered friends fill the skies of North America during migration, many people are left wondering—what is migration all about? Who migrates? Why? And how?

Here are a few facts that you’ll find useful as you try to navigate your way through a season filled with skeins, sords and gaggles of migrating birds.

Who Migrates?

Not all of the birds found in Canada are migratory. In fact, many stay to keep us company throughout the year. So, which birds do migrate? Here’s a listing of some of the more common types of migratory birds found in Canada:

Waterfowl (such as ducks and geese)
Raptors (such as hawks and eagles)
Wading birds (such as cranes, herons, gulls, terns and shorebirds)
Songbirds (such as sparrows, warblers, blackbirds and thrushes)

Over the centuries, people have come up with interesting names for flocks of different types of birds. A flock of geese, for instance, is called a "skein" when in flight and a "gaggle" when on the ground. Similarly, a group of mallards is referred to as a "sord" when in flight and a "brace" when on the water. Here are some other interesting group names for birds:

A "murder" of crows
A "parliament" of owls
A "tiding" or "charm" of magpies
An "exaltation" of larks
An "unkindness" of ravens

Grebes, geese and ducks are just some of the many migratory birds found in Canada.

Why Do They Migrate?

Migration is a complex behaviour. It’s a journey that requires a great deal of energy and effort to survive. But if it’s such a harrowing experience, why do birds bother to migrate at all? Basically, birds migrate to enjoy the benefits of good habitat conditions all year round. During the spring and summer, they take advantage of conditions in the north that provide abundant food along with good breeding and nesting habitat. Once fall rolls around, they make the arduous journey to enjoy these same types of habitat benefits further to the south.

When Do They Migrate?

Different species have different ways of knowing when it’s time to migrate, but it’s generally a combination of biological and environmental factors that tip them off. Biologically, many species seem to have an internal clock that kicks in and causes their bodies to start preparing for migration. These preparations include a slowing of metabolism (which allows birds to build the fat needed to fuel their flight), increased feeding and general restlessness.

On the environmental level, the shortening of daylight hours in the fall and the lengthening days in the spring helps cue the birds into migration mode. Temperature changes also mean that wetland habitats are either about to freeze (in autumn) or thaw (in spring), meaning it’s time for the birds to move on. In addition, food and water sources are limited in the fall and may be sparse if the birds return north too early, so the birds need to time their departure carefully.

Where Do They Migrate?

Generally speaking, migratory birds go where they can find the food and resources they need to survive. Waterfowl, for example, will go to areas that have proven to be rich in resources during past migrations. Unfortunately, the loss of wetlands has reduced the number of habitats available to these birds throughout the season.

Different species of birds migrate to different areas. Those that migrate north to Canada for the spring and summer generally come here to breed and nest. During this period, most can be found spread all across Canada. Many migrate farther north to the coastal areas of Alaska and the Canadian territories.

During the fall, many of the more common migratory birds found in Canada migrate to the southern United States and northern Mexico, in the coastal regions around the Gulf of Mexico. Other birds prefer the eastern and western coasts, while still others spread themselves all over the United States. Many continue their journey beyond North America, like the many species of songbirds that travel to central and South America.

Page 2: How Do They Migrate? >>