Now that spring is in the air, the UK is starting to see its holidaymakers arrive. Ospreys are already back in their neststhe chicks sing their song to restore their territoriesand the puffins arrived at their breeding sites around the British Isles.
Many centuries ago, swallows were believed to spend the winter asleep at the bottom of ponds and lakes, or even on the moon – but of course, it was complete nonsense.
We now know that animals migrate to increase their survival – and that of their offspring. It also helps them in their quest to find food, a mate, or to avoid predators.
Although we tend to think of migration as birds flying from one country to another, there are actually lots of migrating animals. The wildebeest, for example, undertake a circular migration, roaming the African plains in large numbers during the dry season in search of fresh grass. And humpback whales migrate to warmer waters to raise their offspring.
However, it is the birds that break travel records.
the bar-tailed godwit has the longest non-stop migration on record, with one person spending almost ten days traveling from Alaska to New Zealand without a break – it’s a whopping journey of around 12,200 km (7,580 miles).
But the arctic tern is the true champ, making a 35,000 km (22,000 mile) round trip from the Arctic to Antarctica and back every year. This huge migration means it experiences a constant summer – enjoying more daylight than any other animal – as it stops in countries like Mauritania, Ghana and South Africa, during its world hiking.
How birds find their way
Migration is an expensive activity – birds must carry enough fat stores to propel their flight and sustain themselves for the duration of their journey. Getting lost could have disastrous consequences, which is why birds have developed incredible navigational skills to help them navigate the shortest and safest routes.
Some species have an innate and inherited ability to migrate, allowing them to independently move to areas to improve their survival.
The cuckoo, for example, is not reared by its parents because the mother cuckoos lay their eggs in nests belonging to birds of a completely different species. However, a young cuckoo is able to travel alone, from Europe to Africa, and vice versa, using a “Internal GPS”.
But some species, such as the Caspian tern – which undertakes a long-distance migration from its breeding ground in northern Europe to its wintering grounds in Africa – have inherited very little of their migratory habits. In most cases, they receive education from their parents, also called “cultural heritage” or social learning.
A recent study, for example, found that young Caspians seem find out about your migratory route of their father, who bears the main responsibility for the migration with their young birds. Throughout the journey, he also tells them of stopovers suitable for refueling with fish and shellfish.
But whether genetically or socially inherited, birds use a variety natural clues, such as the shape of the coast or the position of the Sun or the stars – or olfactory clues like the smell of their nest – to help them navigate around the globe.
Read more: Birds use massive swipe cards to migrate – and some could span the globe
Some birds, such as carrier pigeons, even use a magnetic card to align with the earth’s magnetic field as they move.
UK summer visitors
Our knowledge of bird migration has increased dramatically since the development of biologgers, tiny data-logging devices attached to birds. These allow us to track an individual’s location, speed, stopover sites and time of migration.
One of these studies is the peekaboo tracking project. This revealed that several cuckoo clocks left central Africa around the start of 2022, each traveling hundreds of kilometers separately before stopping for a few weeks in countries like Ivory Coast and Morocco. They then continued with the next leg of their journey, and the northernmost bird had reached France around April 10. These migratory cuckoos are expected to return to their breeding grounds in the UK very soon.
And they are not alone. Many birds undertake long-distance migrations to the UK for the summer breeding season. For example, the wheatear also winters in Central Africa, but is back in the UK much earlier, from late February to mid-August, when the hobby – a predator of dragonflies – winters in South Africa and is found in the UK from late April to October.
This allows them to take advantage of the long hours of daylight and the abundance of food, such as insects, during the summer months in the UK.
Read more: Garden bird feeders boost blue tit numbers – but leave other species hungry
If you want to help the birds during their breeding season – and at the same time help other more permanent avian residents, like chickadees and sparrows – here are some ideas.
Feeding the birds nuts, seeds and household scraps such as pastries, fruit or cheese will help provide easily accessible food.
But some species, like house swifts and swallows, depend on insects. Thus, improving the biodiversity of your garden by create a wildflower meadowor participate in no mowing may – an initiative by UK conservation charity Plantlife asking everyone to ‘lock up their lawnmowers’ and let the vegetation grow during the month of May – will also be hugely beneficial.
Don’t forget that birds also need water, for drinking and bathing, so a small birdbath or wildlife pond is ideal. You can also put up nest boxes to provide even more resources for our returning birds – an excellent substitute for the lack of natural nesting sites to raise young, especially in urban areas.
Waking up to the chirping of birds, courtesy of our summer visitors, including willow warblers and nightingales, brings joy to so many of us. Let’s not forget the epic journey they undertook to reach our shores – and do what we can to ensure a successful breeding season.