Whether it be in spring or fall, migration is a truly awe-inspiring phenomennon. In North America, most bird species migrate to some extent, with more than 350 species traveling between their summer ranges in the U.S. and the tropics each fall to overwinter. Here are just some of the many incredible facts about our migrants.
1. At least 4,000 species of bird are regular migrants, which is about 40 percent of the total number of birds in the world. (Although this number will likely increase as we learn more about the habits of birds in tropical regions.)
2. Birds can reach great heights as they migrate. Bar-headed geese are the highest-flying migratory birds, regularly reaching altitudes of up to five and a half miles above sea level while flying over the Himalayas in India. But the bird with the record for the highest altitude ever is the Ruppel’s griffon vulture, which collided with a plane at 37,000 feet (that’s seven miles!) in 1975 and was unfortunately sucked into its jet engine.
3. The Arctic tern has the longest migration of any bird in the world. These black-capped, red-billed birds can fly more than 49,700 miles in a year, making a round trip between their breeding grounds in the Arctic and the Antarctic, where they spend their winters. The lucky bird gets to see two summers a year! And over its lifespan of more than 30 years, the flights can add up to the equivalent of three trips to the moon and back.
4. Speaking of long distances, the northern wheatear travels up to 9,000 miles each way between the Arctic and Africa, giving it one of the largest ranges of any songbird. What makes this an amazing feat is that the tiny bird weighs less than an ounce, on average.
5. The award for fastest bird goes to the great snipe: It flies around 4,200 miles at speeds of up to 60mph! No other animal travels at such speeds for such long distances. Birds usually utilize tailwinds (winds blowing in the same direction they fly) to help them go faster, but the snipe’s speeds don’t seem to be a result of that.
6. The bar-tailed godwit can fly for nearly 7,000 miles without stopping, making it the bird with the longest recorded non-stop flight. During the eight-day journey, the bird doesn’t stop for food or rest, demonstrating jaw-dropping endurance.
7. Migration can be extremely dangerous for birds, and many don’t often make it back to their starting point. Sometimes natural occurrences like harsh weather play a role, but many times, human activities are the cause of birds’ untimely demise. In the United States alone, up to one billion birds die each year from window collisions. And approximately seven million die from striking TV and radio towers in North America annually, ABC News reports.
8. To prepare for the extremely taxing effort of migration, birds enter a state called hyperphagia, where they bulk up on food in the preceding weeks to store fat, which they’ll later use for energy on their long journeys. Some birds, like the blackpoll warbler, almost double their body weight before flying 2,300 miles non-stop for 86 hours.
9. Even birds that don’t fly migrate. Emus, the large Australian birds, often travel for miles on foot to find food, and many populations of penguins migrate by swimming.
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Why Birds Migrate
Given their small size, birds need a tremendous amount of energy to fly across mountains, oceans, and hemispheres. So, what motivates this strenuous effort?.
There are many variables that affect migration, but two main ones stick out: the need for adequate nesting habitat and the need for food.
Over millions of years, every species of bird has evolved to consume particular foods. Every species of migratory songbird has a different diet, but the majority of them consume seeds, berries, fruits, insects, aquatic invertebrates, grains, larvae, and buds. Many birds migrate to warmer regions when the seasons change because these foods are still plentiful there, giving them the energy they need to meet their needs all year round.
As an illustration, the common yellowthroat is a migratory bird species that primarily consumes insects, such as moths, caterpillars, grasshoppers, dragonflies, and beetles. This implies that it must adhere to the temperature at which insect populations are increasing. Additionally, some birds are known as aerial insectivores, and they consume insects while they are in the air. A type of aerial insectivore, chimney swifts consume only flying insects—roughly 1000 flying insects a day, or one-third of their body weight—to survive. As a result, insects must be readily available to these creatures. However, as summer transitions into fall and fall into winter, fewer and fewer plants and insects are available, which causes birds like these to migrate by following flyways to temperatures where insect populations are booming!
Some species primarily consume seeds, such as common redpolls, pine siskins, and American goldfinches. These birds use their specially designed beaks to crack open seeds to forage among grasses, weeds, trees, and shrubs. To help them survive the chilly winter nights, pine siskins can even store seeds in their crop, which is a portion of their esophagus. Redpolls, on the other hand, have a throat pouch where they can temporarily store seeds. Now those are special adaptations for their food sources!.
Then there are the migratory predatory species, which include raptors like Cooper’s and broad-winged hawks. If their prey (which includes other birds like the species we just mentioned) is migrating in search of food, then they too must follow their food sources and migrate. The osprey starts its annual migration to find plenty of food when the water temperatures drop and fish migrate to warmer waters.
One of the main reasons birds migrate is to nest, which goes hand in hand (or, in this case, wing-in-wing) with their migration for food. Birds travel to areas with an abundance of resources so they can find a mate, build a nest, lay their eggs, and raise their young. From a biological and evolutionary standpoint, the most significant activities for birds are mating and building nests, both of which require abundant resources to be accomplished.
Many blue-gray gnatcatchers, a neotropical migratory bird species, move from their nonbreeding grounds in the tropical regions of Central America to the forests and wooded habitats throughout the United S. Together, the males and females will select a secure location for their nest, then construct it. Their cup-shaped nest is really interesting because it is only two to three inches wide and the materials are connected by spider webs or caterpillar silk. Amazingly, they have even been known to affix lichen, hair, or bark fragments to the exterior of the spider web as ornaments. And even after all that labor, they construct multiple nests throughout the season to fend off mites, predators, and cowbird parasitism. They should ideally have two clutches per season, with each clutch containing three to five eggs. This implies that during the breeding season, the parents are continuously building their nests, tending to the hatchlings, feeding them all, and releasing the chicks from the nest. In addition, they must have sufficient energy to begin their migration back to their non-breeding grounds, where they will spend the majority of the year. Sounds exhausting!.
Using similar materials, ruby-throated hummingbirds also construct a tiny cup-shaped nest. They diverge, though, in that the male ruby-throat hummingbird departs from its Central American wintering grounds a few weeks ahead of the females. The males leave the nest and spend the remainder of the season fending for themselves after courting and mating in their breeding grounds across eastern North America. According to scientists, this might be done to prevent the chicks and females from fighting for the same resources. The females will then construct their minuscule nests, which are only two inches wide, in the branches of deciduous trees. During the breeding season, they should ideally lay one to three clutches of eggs. Ruby-throated hummingbirds, like other hummingbird species, have coevolved with a variety of plants and schedule their migration to occur during the times when native plants bloom where they end up. In this manner, the plants gain from pollination that occurs when the birds gather nectar, and the birds benefit from having food and resources for their nests. When the weather gets colder, females will feed their chicks insects and nectar, which are primarily found during the warm seasons. At that point, they start to migrate back to South America, where they will continue to enjoy warm weather and have access to food and supplies.
In many bird species, migration isnt a one-size-fits-all behavior. This is especially true for species where some birds migrate and others remain in one location throughout the year, such as partial migrants.
For instance, only the juveniles of the wood stork—the only native stork in North America—fly north after nesting season, whereas the adults migrate in response to food availability. This makes the wood stork a partial migrant. These massive wading birds construct their nests in mangroves and cypress swamps together after mating for life. They typically construct their enormous nests in trees above water using sticks and other vegetation as a barrier against racoons and snakes, which are ground predators. The pair returns to the same nest every year, with the males typically showing up a few days ahead of the female to fix and expand the Their annual migration may also be influenced by patterns of precipitation, which may have an effect on the security of their nest and the availability of food.
Certain birds migrate only short distances, while others migrate over extremely long distances. The arctic tern, in fact, has the world’s longest migration, flying over 55,000 miles from pole to pole each year between the Arctic Circle and the Antarctic. Amazing!.
What do birds need to make the journey?
Day length, weather, the local environment, the availability of food, topography, geography, and other factors can all have an impact on migration. It’s nearly overwhelming to consider all the variables that could influence a bird’s decision to migrate.
What would you need if you were an arctic tern preparing to embark on that arduous journey across the globe?
If you said habitat, you’re right!
During their migration, birds like the Arctic tern need safe places to stop and replenish their food and water supplies. Certain species require marshes, while others require forests, meadows, or grasslands. Some species also require shorelines because they follow the coastlines of oceans. Since every bird has a different preference for habitat, it’s critical that the landscape have a wide variety of habitats available for them to use. These locations are known to biologists as “stopover” habitats because they are where birds stop to feed, rest, and look for protection from predators. Because so many birds congregate at certain stopover locations to rest before continuing their migration, some of them are so big that they are even referred to as “staging areas.” USFWS.
For instance, the Platte River in central Nebraska is home to one of the most well-known staging areas in the world, hosting over 500,000 sandhill cranes in a spectacular migration display! The Platte and other shallow water wetlands offer safe havens for refueling and resting, as well as protection from predators and other migration hazards. They eat corn kernels from the surrounding cornfields as well as some invertebrates like snails and worms. But it’s not just sandhill cranes that use the area. Millions of other migratory birds, such as geese, ducks, songbirds, and even threatened and endangered species like piping plovers, interior least terns, and whooping cranes, find the central Platte River and its flat valley to be extremely important.
7. For birds, migration can be extremely dangerous, and many rarely return to their breeding grounds. Though harsh weather and other natural events can have an impact, human activity is often the cause of birds’ premature demise. Every year, window collisions claim the lives of up to one billion birds in the United States alone. According to ABC News, roughly seven million people in North America lose their lives each year as a result of striking TV and radio towers.
4. Speaking of long distances, the northern wheatear travels up to 9,000 miles each way between the Arctic and Africa, giving it one of the largest ranges of any songbird. What makes this an amazing feat is that the tiny bird weighs less than an ounce, on average.
5. The award for fastest bird goes to the great snipe: It flies around 4,200 miles at speeds of up to 60mph! No other animal travels at such speeds for such long distances. Birds usually utilize tailwinds (winds blowing in the same direction they fly) to help them go faster, but the snipe’s speeds don’t seem to be a result of that.
8. To prepare for the extremely taxing effort of migration, birds enter a state called hyperphagia, where they bulk up on food in the preceding weeks to store fat, which they’ll later use for energy on their long journeys. Some birds, like the blackpoll warbler, almost double their body weight before flying 2,300 miles non-stop for 86 hours.
1. About 40% of all bird species worldwide are regular migrants, making up at least 4,000 different species. (However, as we discover more about the habits of birds in tropical areas, this number is probably going to rise.) ).
FAQ
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