Food and nesting space are simple answers! Birds migrate to improve their chances of survival and reproductive success, and while temperature may influence bird migration, birds can survive in very cold conditions. Their main reason for bird migrating is to follow their stomachs (aka food) and find safe spaces to nest. It’s one of the wonders of the natural world and, if you’re fortunate enough to witness migrating birds en masse, it’s a spectacular sight.
Many birds migrate in line with vegetation changes. Wind, precipitation, and temperature affect the changes in vegetation and consequently available food and space for nesting – which is why bird migration is seasonal. These resources and conditions make areas more live-able at various times of the year. Migrating to areas with more abundant resources improves chances of survival and also impacts breeding success.
See also: how to start birdwatching
A history of bird migration
Where do birds migrate to?
Birds in North America fly towards Central and South America. The paths they choose are usually following coastlines or mountain ranges. Whether they are travelling a few miles or thousands, birds are migrating to avoid conditions that are a threat to their survival. Winter in North America means that the flowers that the ruby-throated hummingbird drinks nectar from disappear, leaving no choice for them other than to travel to Central America for the winter where food is plentiful.
See also: Why is birdwatching important?
Which bird migrates the furthest? How far do they go?
The Arctic Tern, tiny as it might be, is known as the world’s longest migrator. Every year, this little bird flies from the Arctic Circle to the Antarctic Circle, an arduous round trip of about 30,000 kilometres (18,641 miles). However, because they follow a strange zig-zagging pattern that means they don’t have to fly into severe winds, the journey is probably longer every year. Arctic terns are perfectly built for migration. They prefer gliding in the air, letting ocean breezes carry their lightweight frames for great distances, they can even sleep and eat whilst gliding!
The Bar-tailed Godwit is another bird with a lengthy migration, travelling from Alaska to New Zealand. Astoundingly, they do not stop along the way, flying more than a quarter of the way around the world (a distance of around 11,000km or 6,835 miles) for 8 or 9 days straight. It’s the longest non-stop migration ever recorded. To complete this incredible feat, the godwits, like many of their long-haul cohorts, have to prepare before undertaking the journey. They spend weeks building up huge fat reserves (essentially their fuel) so that by the time they leave, more than half of their bodyweight is fat.
How many bird species migrate?
Nearly half of known bird species, around 4000 species, are classified as regular migrants, meaning they make their international journeys every year moving from one habitat to another with the changing seasons. As we learn more about the habits of birds in tropical regions, this number is likely to increase. Not all bird species need to fly to migrate. Many populations of penguins migrate by swimming and Emus, the large Australian bird, will often travel for miles on foot to find food.
Of these 4,000 or more species of migrant birds, most breed in the northern latitudes of the hemisphere. To fulfil their migration goals, these species will all follow different patterns be it in route, speed and timings. Some complete their migratory routes in a very short time, particularly certain aquatic species, and others will make a more leisurely trip, often stopping along the way to feed. Some species of warbler are known to take up to 60 days to travel from their winter habitat in Central America to their summer breeding areas in Canada. Many of the smaller species migrate at night and feed by day and others migrate primarily in the daytime.
How do migrating birds know where to go?
There are many species, particularly waterfowl and cranes, that follow the same migratory route year after year, even using the same stop-off points because of their plentiful food supply. Some young birds also learn the routes from their parents. If the birds are raised in captivity then humans have been known to teach them, this video shows whooping cranes being taught to migrate by a light aircraft!
Where can I go to see migrating birds?
There are a huge number of places globally that you may catch migrating birds. Many birds stop off for refuelling at key places along their migration routes.
In North America, the birds that migrate do so in the late summer through the autumn (fall) and in the late winter through the spring and generally follow a north-south pathway. As birds fly overland for long periods of time, there are many places to spot migrating birds. Cape May Point in southern New Jersey is a known stop-off point for migrating hawks making their way south. The Finger Lakes region of upstate New York attracts waterfowl in fairly high numbers and more than half a million Canada geese pass through the Montezuma Wetlands Complex, near Seneca Falls. In southern Arizona, a collection of mountains known as Sky Islands fills with hummingbirds on their way north from their breeding grounds in Mexico.
Autumn in the UK is a brilliant time to see birds arriving and heading off in their thousands. There are many great locations to view migrating birds from Blakeney Point in Norfolk to Land’s End in Cornwall. The remote Orkney Islands are a well-known birding hotspot in September as all the finches and thrushes pass through and the seabird migration reaches its climax.
Where do you live? Have you seen birds migrating near you? Download the Birda app and start posting your migration sightings.