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Last year I become involved with this topic, and after some fascinating articles I made illustrations about the facts which was new to me. Bird migration is one of the great wonders of the natural world. A huge variety of birds make the journey: the tiny Rufous Hummingbird migrates up and down the North American continent, while the Arctic Tern, BirdLife’s emblem, migrates from pole to pole. In fact, roughly one in five bird species migrate.
At least 4,000 species of bird are regular migrants. That’s about 40 per cent of the world’s total. But some parts of the world have
a higher proportion of migrants than others. The tiny arctic tern makes the longest migration of any animal in the world, covering around 40.000 km.
With such long distances to cover, these birds need resting places along the way. These range from spots of forests and meadows to wetlands and water bodies, where the birds can stop to rest, regain their strengths, quench their thirst, and restock their bellies with food for the journey ahead. A landscape teeming with biodiversity is the most important feature of a resting place for these birds as they not only provide food and water, but shelter as well. The birds fly mostly at night and often for long hours at a time, leaving little time for sleep.
A larger group of birds boasts a much better chance of spotting a predator, or other potential threat, than a single bird has.
A group of birds may also be able to confuse or overwhelm a predator through 'mobbing' (when birds attack or chase a would-be predator, to drive it away) or agile flight. Staying in a flock presents a predator with more possible targets too, which lowers the danger for any single bird.
Light pollution is a seious threat to migratory birds, causing disorientation when they fly at night, leading to collisions with buildings, perturbing their internal clocks, or interfering with their ability to undertake long-distance migrations.
As mentioned earlier, birds migrate during certain times of the day to avoid potential threats. Their biggest threats on the long journey home in the spring include predators like owls or hawks, dehydration, starvation, oil drilling rigs in the ocean, windmills, power stations, and drastic climate changes. All of these hazards are instinctually taken into consideration, but birds are still not completely safe during their journey.
Instinctively, migrating birds know where to migrate and how to navigate back home. They use the stars, the sun, and earth’s magnetism to help them find their way. They also almost always return home to where they were born. Because of this, you could be right if you think you see the same bird each year in your yard.