Changing weather conditions force birds to migrate. After busy breeding and rearing of offspring, birds undertake a difficult and long journey. They fly off mainly to Africa, but not only. In spring, they return to once again carry out breeding. Read more about this phenomenon ⤵️
Migratory birds are characterised by a lighter colouration of their feathers. According to scientists, this is one of the adaptive traits developed to survive long and difficult journeys to remote areas. The lighter plumage reduces the risk of overheating when exposed to the rays of the sunlight.
The phenomenon of bird migration continues to fascinate scientists and amateur observers of these animals. Every year, at the beginning of spring, many eagerly await the first storks or swifts returning to their breeding grounds.
How do we know the migration routes?
Thanks to the method of marking captured birds with metal or plastic rings, scientist have learnt most migration routes of birds. Learning about bird migration routes requires observation by many people in different parts of the world and usually takes many years.
Through observation, we know that the general direction runs from north to south. Most European migratory species head southwest or southeast. The choice of migratory routes and flight altitude depends on the biological capabilities of the species in question, e.g. waterbirds usually fly low, along river valleys or coasts, while typically terrestrial birds usually fly a wide front, on average up to 3,000 m above sea level.
Secrets of bird migration. Can they deviate from their set course?
Small birds fly at a speed of 50-70 km/hr. Smaller birds cover a daily distance of about 100 km, large ones up to 500 km. During the day, many birds orient themselves thanks to the sun, but at night they can estimate direction from the position of the stars. Some follow along river valleys, mountain ranges or sea shores. Some species are sensitive to the earth’s earth’s magnetic field, polarised light, infrared radiation and even unknown changes in atmospheric heat.
The bar-tailed godwit (Limosa lapponica) has officially been recognised as a record breaker in the world of migratory birds. It flew 12,000 kilometres in 11 days, covering the route from Alaska to New Zealand without stopovers. This is the longest flight without rest that scientists have been able to observe and confirm.
Do birds always migrate in groups?
It is a common misconception that birds travel together, when in fact they often travel independently. Flocks of thousands of storks migrating between Europe and Africa, fly over the Straits of Gibraltar or the Bosporus. However, once the birds are overseas, they disperse. Travelling in groups gives young birds the opportunity to benefit from the experience of older individuals who have travelled the entire route many times. During the day, travelling companions can see each other, while birds travelling at night keep in touch with each other by giving short shouts.
A few species of migratory birds and their destinations
The white stork (Ciconia ciconia) is probably known to everyone. It arrives on its breeding grounds in Poland in March. It flies away in August and September. It winters in Africa south of the Sahara and up to the southern edge of the continent. It covers a distance of up to 10 000 km during its migration.
The swallows are agile but extremely fast-flying birds that appear in Poland in April and remain here until September or even October. Swallows arriving in Poland overwinter in Africa.