Birds migrate for two main reasons:
to find new food sources
to find a good place to raise a family
With their superb flying ability, speed, hollow bones and excellent navigation skills, birds are properly equipped to travel thousands of miles, which gives them plenty of options in the search for food.
Birds that nest in the UK tend to migrate north in the spring to take advantage of the growing insect population, abundance of nesting locations and new plants growing. As winter approaches, and this type of availability diminishes, birds need to find new sources of food and shelter.
Migration tends to be initiated once a combination of day length change, cooler temperatures and changes in food supplies start to happen.
Which birds migrate?
The most well known regular migrants are classed as long distance migrants such as swallows. It's thought that around 4,000 bird specifies are regular migrants around the world.
Some birds, such as warblers, nightingales and yellow wagtails, spend spring and summer in the UK so they can breed, and then return to warmer climates for the winter months.
In the winter, our resident Blackbirds (pictured above) are joined by individuals from elsewhere in Europe, such as Russia, Poland and Germany.
Other birds including bramblings and many species of duck and swans travel to the UK over winter; this is because the ground is less frozen and they are likely to find more food.
Not all species of bird migrate however, there are some, such as Blue Tits, Chaffinches, Robins and Wrens, which can be found in UK gardens all year round.
How do birds navigate their way?
Birds can often cover thousands of miles annually, often travelling the same course every year with little to no change. Even young birds can make their first migration on their own, and yet find their winter home despite never going there before. And interestingly finding their way back to their birth place the following spring.
Though we will never fully understand their navigation secrets, birds combine several of their senses to travel.
Visit the British Trust for Ornithology’s (BTO) website for further details.