Dangers of migration

Bad weather is bad news for migrating birds.

In tropical regions, sandstorms and wildfires can cause similar problems, while storms at sea can drive birds into the waves, where they drown. 

New arrivals need to start feeding quickly, so bad weather at their destination – such as late snowfall – can also spell disaster.

Many predators have migrating birds on their menu.

Eleonora's falcons nest on cliffs in the Mediterranean. Their chicks fledge in August, just when millions of songbirds are crossing the sea to Africa. This is much later than most small birds. It means the parents can catch plenty of food for their growing youngsters.

Resting along the way can also be risky. White storks roosting overnight on the African savannah may fall prey to expert bird-catchers like the serval cat.

Birds do get lost, despite their navigation skills. Youngsters on their first journey south can easily go astray - especially if they meet bad weather.

Every year, a sprinkling of rare ‘vagrants’ reaches the UK. These may have been blown too far west from Asia (such as the Pallas’s warbler), or too far east from America (such as the Baltimore oriole). Many are too weak to survive for long, and few find their way home. 

Some birds have amazing stories to tell – an American wigeon that reached the UK by accident found its way back over the Atlantic to its home in America. 

Some ‘lost’ individuals even settle in their new home – a black-browed albatross from the Antarctic ocean (nicknamed ‘Albert’!) lived for many years among a colony of gannets off northern Scotland. We don’t know whether he ever got lonely!

Tall man-made objects can be deadly to migrating birds.

Lighthouses are among the worst. Birds reaching the coast are attracted to the light, but as they get closer they become blinded and crash into the tower – sometimes in their thousands. 

The RSPB has successfully campaigned for many lighthouses to be floodlit, which helps birds to see the towers and avoid them. Burning flares on floating oil and gas platforms cause similar problems at sea – birds fly towards the light and are killed by the flames. 

Skyscrapers, television aerials, radio masts and power lines also kill many migrating birds each year. Migration routes took thousands of years to develop; evolution hasn’t prepared birds to cope with these modern hazards.

Migrating birds need safe places to provide food and rest along the way. In the UK, wetlands, such as marshes and estuaries, are havens for migrants.

Swallows, wagtails and other small birds roost in reedbeds, while wading birds gather to feed on the rich supply of food beneath the tidal mud. One estuary – such as the Wash in Lincolnshire – may host hundreds of thousands of birds every year. 

You won’t see them all at once, since they pass through in waves. But each bird depends upon the few days that it spends there. If people damage these places, or disturb the birds while they are roosting and feeding, the birds have nowhere to recover and refuel. They may never gain the energy they need to finish their journeys.

Along the southern edge of the Sahara there is a grassland region called the Sahel. This is where millions of hungry migrants find food after crossing the desert.

But overgrazing by cattle has done terrible damage to the Sahel – the soil has been eroded, the plants are disappearing and the whole region is drying up. 

This has made the Sahara desert wider, and some birds – such as sand martins – now find it much harder to cross. Sand martins no longer visit Europe in the same numbers they did 50 years ago.

Oil spills at sea kill millions of seabirds as they wander the seas during winter. Oil clogs a bird's feathers, making it unable to fly or keep warm.

After the Torrey Canyon oil spill in 1967, about 10,000 dead seabirds washed up on English beaches. Even worse spills have happened elsewhere. Scientists estimate that the 1989 Exxon Valdez disaster in Alaska killed between 90,000 and 270,000 sea birds. 

And we only ever find a small proportion of the victims. Up to 90 per cent of oiled birds probably drown and sink without ever being seen. Oil also kills other marine life, so in the long term it also damages the food chain that seabirds depend upon.

Migration routes cross many different countries, so conservation organisations such as the RSPB have to work with other organisations and governments all over the world. After all, there is little point in protecting birds in the UK if their winter home in Africa is destroyed, or if they get shot during migration.

Today most countries have laws to protect migrating birds and their habitats, and international agreements help to make sure that these laws are followed. 

The Ramsar Convention on wetlands was agreed in 1971. It aims to protect all important wetlands around the world, and to make sure that people use them without damaging them. Today 138 countries are signed up to this treaty. The UK now has 169 Ramsar sites – more than any other country.