Amy Hall discusses the genius behind seasonal bird migration, explaining how and why some birds arrive in the UK in particular seasons. Also touching on the increasingly problematic impacts on bird migration from climate change.
If you had wings, where in the world would you go? As a human, I would ponder this question for a while before spouting a well thought out answer. However, for birds, their instinct tells them where to go without any thought. Without google maps or a calendar on the wall, every year migratory birds will still fly exactly where they need to go.
In spring, the pressing matter of breeding season forces over half of the world's bird population to move around the globe, in search of longer days and an abundance of food to successfully rear their chicks. This is known as seasonal migration and brings to the UK a plethora of summer migrants. Some of the most well-known summer visitors that you might recognise are cuckoos, swallows, swifts, and nightjars, just to name a few. Some birds fly hundreds of miles, all the way from Africa, others take the short-haul option and come from Mediterranean countries. Or some travel from other oceans, particular seabirds, such as gannets and auks, will spend a long, treacherous, winter out at sea before coming inland to lay their eggs in Spring.
Breeding gannets on a cliff edge in Helgoland, Germany. Image credit: Amy Hall.
When Autumn comes around, it all changes again, learning bird identification is no easy feat with an ever-changing selection of birds. Our summer visitors will leave to make way for our winter visitors. For some birds that don’t breed in the UK, they will leave their country after their breeding season ends to make use of our mild winters and abundance of winter food. This tends to be a lot of ducks, geese, and waders. We’ll even get treated to a different selection of seabirds such as great northern divers or common scoters make use of our warmer winter waters. In Autumn, migration isn’t as noticeable as it is in Spring. Summer migrants take their time to leave, while the Autumn visitors take their time to arrive, making the transition a slow one. With no offspring to feed through the winter months, there’s no need to rush. Perhaps the most well-known winter spectacle as a result of migration, is the starling murmuration, people flock to starling hot spots just to watch this every winter. With only a short time frame to watch, this is a prime example of the wonders of bird migration.
Starling murmuration at sunset over the Irish Sea in Lancashire. Image credit: Pete Godfrey on Unsplash.
Throughout the world there are bird migrations. But nothing is left to chance, every migration follows a pathway. Often, many birds will follow the same pathway every year, this is known as a flyway. When birds know it’s time to go, they experience a surge in hormones, triggered by a change in climate. What has always baffled me about migration is, without the use of maps or road signs how could they possibly know which way to go? As it turns out, there’s lots of natural ways birds know which direction to head in. Some use the position of the sun and the moon and sometimes the stars if there aren’t too many clouds. Sightseeing on their travels is a helpful pastime for birds as remembering specific landmarks can be a useful reminder to our feathered friends that they’re on the right track. Finally, and quite possibly the most fascinating adaptation, some birds can use the Earth’s magnetic field as a built-in compass if they’ve got a mineral called magnetite present in their skulls.
An example of migration flyways. Image credit: L. Shyamal on Wikimedia Commons.
Unfortunately, migration is becoming increasingly tricky for some birds. With ever changing landscapes due to human development and the climate becoming more unpredictable each year. All the natural cues that birds rely on are becoming jumbled. Climate change is causing seasons to change beyond recognition, weather is becoming more unpredictable, and the natural cycles are being thrown off balance. With warmer weather, some birds are being triggered to migrate earlier, leading them to a destination where food isn’t available yet. Making it almost impossible to keep hungry chicks fed. The natural landmarks that some birds rely on to follow their flyway are being destroyed or disguised by human developments, if birds are thrown off their path it can be detrimental. This human development also means that if birds do reach their end goal, they’re being met with a lack of nesting sites. A bird that is really being affected by this is the swift that visits the same nest site every single year, with these sites disappearing, they spend their whole summer season finding somewhere new to nest, leaving no time to breed before Autumn.
Common swift clinging to the wall outside of manmade nest site. Image credit: XJochemx.nl on Wikimedia Commons.
But not all hope is lost, there are small ways that you can help. Putting up bird boxes and leaving out food in your garden, gives the birds a guaranteed place to nest that is going to stay consistent for years to come with a supply of food at the ready. Bird food isn’t recommended during breeding season, however, as it’s not always easy for chicks to digest, it’s best to save the seed and fat balls for winter when birds need to fatten up and keep warm. This being said, summer chicks desperately need food too, they mainly eat soft, squishy, insects so if you’ve got an outdoor space, attract insects with wildflowers and bug hotels. All year round, you can make small sustainable lifestyle changes to tackle climate change, and if we all do something small we can make a huge difference. If you want to go the extra mile and do something big, advocate for the rights of our migrating birds. Write letters to your MP, peacefully protest against things that may risk the lives of our birds, sign and share petitions on social media, or simply spread awareness amongst your peers. Doing this, we can ensure that our birds will carry on visiting us year on year.
About the Author: Amy Hall is a HUGE nature nut, living in Cornwall, England. Living in one of the most beautiful places in the country, inspiration isn’t hard to come by. She tries to take advantage of her location and inspire other people to love nature as much as she does. One day, she aspires to do it professionally as a science communicator, hence why she's published her first article in WILD magazine. When she wasn't writing this article, she was trying to show people how fun it can be to get outside over on Instagram @amyinthewild_ or studying a MSc in wildlife biology and conservation. For now, she hopes you enjoy reading ‘wings of change’ as much as she's enjoyed writing it.
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