Bird migration is a fascinating and mysterious behavior. While it makes sense for birds to head off to warmer climates with more plentiful food, how do they know where to go? It’s a great question and thankfully one that has been studied a lot over the years.
Not only do birds know the general area of where they need to go, but they will often return to the exact same breeding grounds. Let’s take a look at how they do it.
It’s in Their Genetic Programming
As humans, we can be guilty of thinking animals are just less intelligent versions of ourselves. Whether it is cats hunting, hibernation with bears, or migrating with birds, many animals have in-built instincts that would be alien to us.
The reason birds migrate and the route they choose can differ between species. However, it’s usually driven by changes in temperature, a lack of food availability, or breeding opportunities. Also, it may seem common practice, but only around 20% of bird species migrate.
For those that do, it’s simply a part of their genetic makeup. Even birds without any learning have been shown to fly at the right time and in the right direction. It’s an innate ability coded into their genes through millions of years of evolution.
They Use Natural Landmarks
While birds may know where to go, they still use landmarks to help them. This is similar to humans giving each other directions. As well as telling someone the road to go down, you may also tell them what buildings or features they’ll pass along the way.
For birds, these landmarks are usually large geological features such as coastlines, mountain ranges, and rivers. This allows them to not only stay on course, but it can also be useful in making their journey easier.
For example, storks and hawks will use thermal updrafts over land in order to conserve energy. This can include avoiding water crossings as they can reduce rising air currents. They may have innate abilities to migrate, but they still need to choose the best path to get there.
Some Can See the Magnetic Field
Some animals have capabilities that can be hard for us to understand. One of those is a bird’s ability to see magnetic fields. These specialized cells in their eyes allow them to use the magnetic field as a compass.
They can see these magnetic fields as patterns. You can imagine it like us humans seeing the aurora borealis, but for birds, these visual patterns are stable and reliable. Not just as a compass, but it gives birds plenty of information on their complete orientation.
Another incredible fact is that some birds use smell to navigate. They use chemical cues to locate their breeding grounds when they have little other information to rely on. This is especially important for birds traveling over areas with no visual landmarks, such as the sea.
Navigating the Stars
One thing we have in common with birds is our ability to navigate with the help of the stars and moon. Of course, most of us now put on our GPS instead but birds still use these movements to maintain their course.
Birds that migrate through the day such as swallows can use the position of the sun and its movement across the sky to maintain their course. Nocturnal migrants, which includes many songbirds, rely on the stars.
How do Birds Learn to Migrate?
Not all birds fly. And many birds don’t need to learn how to migrate, but experience still helps. For example, if you lived all your life in the same town being driven around by your parents, you’ll most likely know your way around semi-automatically once you learn to drive.
As children learn from their parents, young birds will also learn from experienced adults. They will learn the routes but also key details that may not be instinctual, such as the best stopover points and the best spots for thermal uplifts.
Added to this is perhaps the most obvious point of all, birds have a pretty good memory. The knowledge will be passed on from one generation to the next and becomes second nature. This learned knowledge can combine with their natural instincts for incredible accuracy when migrating.
How Birds Manage Long-Distance Travel
Now we know how birds know where to go during migration, but how do they physically do it? Some birds travel over 10,000 miles (16,000 km) but what do they eat, where do they sleep, and how do they not become exhausted?
Perhaps the most fascinating fact about birds is how they sleep. Instead of tucking themselves into a warm cozy bed, birds can sleep while flying. They can shut off half of their brain at a time for non-stop migration. Many will sleep by taking incredibly short naps, around 10 seconds long, hundreds of times per day.
Not all birds will fly non-stop as many others will rest for food and water. They’ll look to find a safe stop and perhaps catch some prey before heading off again. Birds that fly non-stop usually rely on catching insects while in the air for nutrition.
Which Birds Migrate
Migration seems a natural thing to do but as we mentioned, only around 20% of birds do it. The reasons for migration can change from one species to another, but it usually has to do with access to food, favorable climates, and safe breeding grounds.
While known for traveling incredible distances, some birds only move around slowly. In fact, even a flightless bird such as a penguin can migrate. If their habitat doesn’t provide sufficient resources all year around, then a bird will migrate.
The most famous birds that migrate include hummingbirds, waterfowl (ducks and geese), cranes, robins, and warblers. Other birds, such as the bald eagle, can partially migrate meaning they will often be happy to stay in one place unless food runs out, at which point they’ll migrate.
Why Don’t All Birds Migrate?
Can a bird survive and procreate in one specific location? Without the cognition that comes with it, this is essentially what each bird species is asking themselves. Birds that don’t migrate usually stay in an area where food is available all year round, even in colder months.
A bird such as an owl is well adept at surviving in colder temperatures and are excellent hunters. This is why most owls don’t migrate and stay in places that don’t have extreme temperature fluctuations, such as most of Western Europe.
A natural question to ask is why don’t birds just stay where they migrate too if food is plentiful? This is mainly due to resources drying up in these places when their own seasons change. With thousands of birds in the same place, one location can’t support a huge number of birds indefinitely.
It’s similar to people who live in colder areas having seasonal homes. It’s nice to get away from the cold for a while but ultimately, they want to go home when the weather gets better.
