Animal migration: Why do animals migrate?

Greylag geese flying in V-formation against a blue sky
Look out for migrating birds and other animals (Photo:

Migration is the seasonal movement of large numbers of animals from one place to another, usually to find more food or better weather. Animals have been migrating for thousands of years and studying changes in their migration habits can help scientists understand how climate change is affecting the planet.

Which animals migrate?

Not all animals migrate, but there are some mammals, birds, fish, amphibians and insects that do. You can see a lot of migratory creatures in the UK as our climate makes the country popular with overseas visitors. These are just a few examples:

Red admiral butterfly
Some butterflies, like red admirals, migrate (Photo: WTML)

Birds – species such as cuckoo, swallow and swift spend the summer months here. Others, such as redwing, fieldfare and some types of duck, goose and swan, fly here in autumn to escape the freezing weather in their more northerly homes. Read more about bird migration.

Butterflies – some types of butterfly, such as the red admiral, migrate here from Mediterranean countries and north Africa in the summer.

Why do animals migrate?

It’s almost always because they need to go where there’s more food, where the climate is more suitable, and – for those birds spending summer in the UK – where they can find a suitable place to breed and raise their young.

Food starting to run out, and changes in the temperature and daylight hours, often signal to animals that it’s time to get moving.

How do animals migrate?

Two swallows sitting on a telephone wire
Spot swallows on telephone wires in autumn (Photo:

There’s safety in numbers so animals often migrate in large groups. In autumn, you often see hundreds of swallows lining up on telegraph wires preparing to set off.

Animals navigate using the sun and stars, as well as landmarks on the ground. They often learn the way from older animals too. Scientists are learning new things about migration all the time – apparently, birds have tiny bits of magnetic material in their brains which work like a compass. Some still get blown off course and end up lost though!

Some creatures travel amazing distances. The red admiral butterfly coming from North Africa covers well over 2,000 miles, and swallows fly around 6,000 miles from their winter homes in Africa!

How to record migration

Cuckoo perched on a pole
Listen for the cuckoo's call in spring (Photo:

You can help us learn more about migration by recording your sightings on our Nature’s Calendar website. We need to know the first time species arrive and the exact date they leave our shores. Here are a few comings and goings to look out for.

Cuckoos start to arrive in the UK in April. Record the first date you hear their distinctive call. Also look out for swifts and swallows arriving at this time of year. We’re interested in when our winter visitors leave too, so record the last time you see any redwings and fieldfares – probably in February or March.

Some red admiral butterflies spend the winter here and you’ll see them starting to emerge from their hiding places in March. Please let us know when you first see one of these butterflies, but only let us know once!

Recording your sightings is easy. Just choose a place you visit regularly and log the first dates you see your each species on our website. By knowing the exact dates seasonal events take place we can better understand the effects of climate change and what this means for UK species. Read our quick guide on how to record.

What animals have you spotted?

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