Spring is coming. Time to fly north! That’s what spring means for lots of migratory birds.
Why do some birds migrate? It’s not only because of the cold. They return to nesting grounds or places with more food. For example, barnacle geese have their babies in the Arctic. There are full days of sunlight and plenty of grass for food during the spring and summer. When cold weather sets in, they migrate south to take advantage of the warmer winters and more abundant food. Just where are those “warmer” winters? Northwestern Europe, where winter temperatures range from 30 to 50 degrees Fahrenheit during the day, and cooler at night. That’s not exactly a tropical vacation!
Not all species fly north to south. The red-necked phalarope flies west from Scotland, across the Atlantic—even across Mexico to its Pacific coast—and then on to Peru each year.
Migration isn’t just important for the birds. It also benefits the ecosystems the fowl pass through. Some species control pests by chowing down on bugs, like locusts, that harm crops. Bird droppings fertilize soil along the way. Seeds in those droppings sprout into new vegetation. And some birds end up as meals for other critters.
How do birds know when and where to go? Scientists don’t entirely understand that. But we do know that God created them with an internal clock and strong instincts. Longer days seem to trigger the innate knowledge: It’s time to head north. Waning food supply may also play a role.
Birds get navigational information from the Sun, stars, and Earth’s magnetic field. Scientists discovered that pied flycatchers often fly at night. The researchers recorded the birds’ in-flight calls as they passed through in the dark. These birds navigate using the stars, landing only to refuel during the day.
God gave some species “superpowers” to help with migration. The peregrine falcon has a long migration of up to 15,000 miles. It helps that peregrines can fly 40-60 miles per hour—as fast as a car—and maintain that speed for thousands of miles at a time.
Bar-headed geese cross the Himalayas, some of the tallest mountains in the world. That high up, the air is cooler, thinner, and easier to fly through. But there’s much less oxygen. So these birds produce more red blood cells. That helps distribute more oxygen through their bodies. (The bodies of human athletes training at high altitudes do this too.) Bar-headed geese also have larger lungs and brains to tolerate those extreme conditions.
Is it by your understanding that the hawk soars and spreads his wings toward the south? — Job 39:24
Why? As spring approaches, you’re likely to see birds passing through your area. Learning how migration works helps us understand how each creature fits into God’s wondrous creation.