How Do Migrating Birds Know Where to Go?

Migration is one of the world's greatest wonders, with billions of birds annually packing their bags and undertaking an incredible journey between their breeding and wintering grounds. When spring migration comes around, we all wonder how they do it. When we travel, we use maps and GPS navigation systems, but migrating birds don't have this technology, so why don't they get lost? Or do they just fly in random directions and hope for the best?

All migratory bird species follow known routes: wintering birds use the Northeast European Flyway to get to us, and summer visitors migrate via the East Atlantic Flyway. Bird migration isn't new; it's been happening for thousands of years. In fact, there is evidence to suggest that birds were migrating during the Ice Age! Even after all of this time, it's still something we don't fully understand.

In this blog, we're going to talk about the aids that birds use to help them travel safely over seas and countries.

What is Bird Migration?

Bird migration is the regular, seasonal movement of birds from one region to another. Most birds migrate between their breeding grounds, where they raise their young, and wintering areas, where food is more plentiful and weather conditions are milder. These journeys can range from short distances to thousands of miles and usually follow the same routes each year.

Why do Birds Migrate?

Birds migrate mainly to survive and reproduce successfully. As seasons change, food such as insects, seeds, or nectar may become scarce, and colder weather can make survival difficult. By migrating, many birds can access better food supplies, avoid harsh climates, and find safer places to breed.

How do Birds Navigate?

The Sun & The Stars

Birds use many celestial cues to guide them. Using the details of the sun's arc as a sun compass, they have an idea of where they need to go. Their ability to pinpoint a route by the position of the sun and moon would suggest that they have some kind of internal clock.

When the sky is clear, nocturnal migrant birds will also use the stars to guide them, focusing on the fixed pole star.

The Earth's Magnetic Field - A Magnetic Compass

There is research to show that birds will use the magnetic fields to guide them, and they instinctively know which way is North and South.

Some species have a mineral, magnetite, in their skull, and it is thought that this picks up on the magnetic forces of the Earth.

Landmarks & Senses

When bird populations migrate, they use landmarks to guide them. This could be hugging the coastline, or following rivers or wetlands. Once they're near a destination, some believe that sound and smell also play a part in the birds knowing where to go.

Travelling Together

The general rule of travel is safety in numbers, and birds use this too. Many birds migrate in groups, and young birds of species like Swans and Geese will migrate with their parents the first time.

This way, they can learn the details of the migration safely and they can be taught when to rest, how to find food sources and the safe paths to take.

How Do Migrant Birds Know When It's Time to Begin Travelling?

Migration is not just a random need for sun; it's when the bird's body tells it when to migrate. The most important signal is the gradual change in day length. As days grow shorter or longer, the bird has an internal clock that responds by the body releasing hormones - preparing it for migration.

Caged birds tend to experience something called 'migratory restlessness', which is where they become active and oriented in the direction they would normally migrate, showing that even without external guidance, migrating comes naturally to birds.

Other environmental cues, such as temperature changes, food availability, wind patterns, and the approach of the breeding season, help fine-tune the timing.

The Challenges Birds Face on Migration Routes

Birds can face serious dangers while migrating. Here are the risks birds face while travelling long distances to make it to their breeding grounds for the breeding season or their wintering grounds.

Challenges include:

• Bad weather and extreme events, which can exhaust birds or push them off course

• Habitat destruction, reducing safe feeding sites and resting areas

• Tall man-made objects such as power lines, wind turbines, and reflective glass walls, which put birds on a collision course

• Light pollution is especially dangerous for nocturnal migrants that rely on celestial cues

• Narrow sea crossings and vast oceans (such as the Pacific Ocean), where there is nowhere to rest

• Mountain ranges and mountain passes, which require extra energy to cross

• Illegal killing and legal hunting, which reduce bird populations

• Climate change, altering seasonal resources and disrupting traditional migration timing

• Wind patterns, which can either help or seriously hinder progress