The barn swallow (Hirundo rustica) is the most widespread and numerous swallow species in the world. These familiar birds travel incredible distances over land and water to spend the spring and summer months in the United States where they nest. By flying south for the winter, these insect-eating birds avoid going hungry when the days get shorter.
American barn swallows undertake an annual migration that takes them from places as far apart as Alaska and Argentina (and everywhere in between). They head south after breeding from April to June and spend the winter months in Central and South America. Barn swallows return when the austral (Southern Hemisphere) summer shifts into fall. Other sub-species follow the same north/south migration across Europe and Asia, traveling south into Subsaharan Africa, Southern Asia, and Australia.
Barn swallow migrations can cover many thousands of miles which is truly remarkable for an animal that weighs less than an ounce! The actual distances traveled vary depending on where the birds breed and overwinter, however.
The great majority of barn swallows will fly south for the winter and return to the north for the summer breeding season. Some populations do things a little differently, however, and there are resident populations in North Africa, and even a group that breeds in the Southern hemisphere in Argentina.
Read on to learn more about the annual migration of one of the world’s favorite bird species.
During migration, Barn Swallows can cover thousands of miles
Barn swallows are long-distance migrants that have a vast worldwide distribution. These streamlined aerial hunters fly between the Northern and Southern hemispheres and back every year.
They do this to take advantage of summer insect swarms. Almost all barn swallows breed in the North and use the Southern hemisphere for overwintering.
Read on for more information about how, when, and why these birds undertake such impressive annual migrations.
Barn swallows migrate by flying quite low to the ground. Their flight is typically very straight and direct, although they are not particularly fast. They can fly at speeds of up to 35 mph, but more often between 16 mph and 22 mph. Barn swallows do most of their flying over land, but some populations will travel considerable distances over water.
Many barn swallows from the Eastern United States, for example, will fly over the West Indies to reach the northeast of South America. Across the Atlantic in Europe, barn swallows also fly over the Mediterranean Sea to reach North Africa but often choose routes with the shortest over-water flight.
A large migrating flock containing thousands of Barn Swallows
Barn swallows migrate twice each year, departing in the fall, and returning in the spring. The arrival and departure times vary depending on how far north and south each population nests and overwinters.
In Southern California, barn swallows can arrive as early as February, but up north in Alaska, the first birds will arrive much later in mid-May. Swallows also need to begin their fall migration much earlier in the north than in the south. Birds in the far north will begin migrating as early as June and July, whereas birds in the south can hang back as late as mid-October.
Barn swallows feed on flying insects that they hunt in the air. This food source is absent or very scarce in the cold winter months, which is why the swallows need to head south where it is warmer and food is still abundant.
Swallow with a hoverfly, caught out of the air
Different populations across America and throughout the world migrate different distances. Barn swallows that breed in Eastern Canada, for example, migrate tremendous distances, overwintering as far south as Argentina. Barn swallows from Europe also migrate amazing distances of as much as 6,000 miles to reach their overwintering grounds.
Barn swallows have been recorded flying anything from 2 to 196km (1-122mi) in a day, with one individual flying an average of 89km (55mi) each day. Read on to learn more about where barn swallows go on their migration, and how long their journey takes to complete.
American barn swallows from the west and east follow different migration routes. Swallows that breed on the west coast of the United States do not fly as far south into South America as those that breed in Canada in the northeast.
Most American barn swallows prefer to fly overland, heading south through Mexico and over the Panama canal, but some brave individuals do fly over the ocean and the Caribbean islands.
Barn swallows will also make use of favorable winds to minimize effort, but since these winds don’t necessarily help them in both directions, the swallows are not always able to follow the same route north and south.
A pair of Barn Swallows perched on a wire
Across the United States, American barn swallows begin to disappear from as early as June and have usually all left by October. The birds are on their way to Central and South America for the winter. South of the equator, the spring begins in September, so these smart birds never have to experience the short cold days of winter.
Barn swallows inhabit a variety of habitats during both the breeding and non-breeding season. Open habitats, especially near freshwater are preferred although only forested and mountainous terrain is really avoided.
The actual time it takes to migrate varies depending on just how far the birds have to travel. Some barn swallows can complete their migration in just a few weeks while others migrate for much longer. Amazingly, some barn swallow populations are known to migrate almost all the time, stopping only for a month or two around June and December.
Barn Swallow perched on a reed
Barn swallows do not fly the whole journey without resting along the way. Even though these birds are able to catch and eat their prey ‘on the wing’, they will still stop to sleep each night if possible. In suitable areas, huge flocks come together to roost in reed beds and fields just after sunset.
Barn swallows migrate and roost in flocks. The roosting flocks in staging areas can be particularly impressive, with some areas supporting over a million birds in a single reed bed! The long-term stability of large flocks is not clear but breeding pairs have been recorded migrating together from their breeding site to the overwintering grounds and back.
A group of migratory Barn Swallows preparing for communal roosting in reed bed
There are several barn swallow subspecies accepted worldwide, and almost all are migratory. One Egyptian subspecies is known to be resident, however. The American subspecies, H. r. erythrogaster (American barn swallow) is highly migratory.
Barn swallows head south for the Northern Hemisphere (boreal) winter. By flying south of the equator, these birds are able to enjoy the austral summer while winter sets in up north in the breeding grounds.
American barn swallows migrate to Central and South America, as far as Argentina. Barn swallows that breed in Europe and Asia also migrate south to overwinter in Africa, Southern Asia, and Northern Australia.
Close up front view of a perched Barn Swallow
Summer is the breeding season for barn swallows. At this time, you can find them all over North America as far up as Alaska and from sea level to 3,000ft. These birds are a familiar sight as they wheel through the skies and skim over the surface of lakes and rivers to catch small flying insects.
Barn swallows build their nests under roofs, bridges, tunnels, and other manmade structures. Look out for breeding colonies near good nesting sites.
Barn swallows migrate during the daylight hours. Of course, birds that fly over water will not be able to stop until they reach land and may need to fly overnight.
Young barn swallows usually don't return to their natal sites. Adults are more likely to return to the same nest site, but this varies widely with as much as 80% of adults returning in some areas and less than 20% in others.
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