Millions of birds follow a 9,000-kilometre invisible highway every year, crossing mountains, deserts and oceans without a map

• Image: AI GeneratedEvery year, as the seasons change, millions of birds undertake one of nature's greatest journeys.
• Some travel only a few hundred kilometres, while others fly thousands without recognising political borders or national boundaries.
• Instead, they follow ancient migration routes known as flyways, natural aerial corridors shaped by geography, climate and the availability of food and resting sites.