Winging South for the Winter
October 01, 2017
As the days grow shorter and the nights grow colder; as long, languid summer melts into crisp, cool autumn; as nature takes on russet hues and puts on fancy dress; as you marvel at the beauty of the season, don’t forget to look up. One of nature’s great marvels is the show in the sky as the birds of North America migrate south. Migration is the annual movement of birds, often north and south along a flyway, between their breeding grounds and their wintering grounds. One of the best known, and certainly the most familiar, of North America’s migrators is the Canada (not “Canadian”) Goose (Branta canadensis). The impressive V-formations of Canada geese flying south are seen all over North America; indeed, Canada geese are found in every one of the contiguous United States and every Canadian province. However, they are not our only journeying birds. “Of the more than 650 species of North American breeding birds, more than half are migratory.” Cornell Lab of Ornithology
Long-distance migration patterns are “controlled at least partially by the genetic makeup of the birds. They also incorporate responses to weather, geography, food sources, day length, and other factors.” Cornell Lab of Ornithology How do birds navigate these vast distances? They seem to use the earth’s magnetic field, landforms and wind patterns, and also celestial navigation (the sun by day and the stars by night). However, we do not fully understand how birds navigate across thousands of miles and come back to the same grounds each year. How do young birds make their very first migration on their own and find their winter home, despite having never seen it before? The migration of birds is one of nature’s great marvels and mysteries.
Did you know?
- Migration comes from the Latin word migratus, meaning “to change.”
- To prepare for migration, many birds enter a state called hyperphagia, where they bulk up on food and increase their body weight to store fat, which they’ll use for energy during their long journey. Some birds almost double their body weight during the weeks leading up to migration.
- At least 40 percent of the birds in the world are migratory (around 4,000 species).
- The birds that fly the highest are the bar-headed geese of India, which regularly reach heights of up to 5 ½ miles above sea level while flying over the Himalayan mountains.
- Another record-holder, the Arctic tern, flies the farthest. The Artic terns fly from their breeding grounds in the Artic to their wintering grounds in the Antarctic every year. Close to 50,000 miles! Over its lifespan of around 30 years, the tern has flown the equivalent of around 3 trips to the moon and back. Audubon.
- The great snipe is the fastest migratory bird. It flies around 42,000 miles at speeds of up to 60 mph. Audubon.
- Records of bird migrations were made as early as 3,000 years ago by Ancient Greek writer such as Homer, Herodotus, and Aristotle.
- “The bar-tailed godwit can fly for nearly 7,000 miles without stopping, making it the bird with the longest recorded non-stop flight. During the eight-day journey, the bird doesn’t stop for food or rest, demonstrating jaw-dropping endurance.” Audubon.
Why do birds fly in a “V” formation?
The V formation is aerodynamically brilliant. Basically, it saves energy and makes flying easier. By taking advantage of the updraft of the flyers in front of them, birds can use 20% to 30% less energy by flying in a V. (Cyclists in a race also take advantage of this aerodynamic principle by “drafting” behind the racer in front, thereby reducing wind resistance.) Pretty ingenious.
Mesmerizing Migration: Watch 118 Bird Species Migrate Across A Map Of The Western Hemisphere
For the first time, scientists at the Cornell Lab of Ornithology have documented migratory movements of bird populations spanning the entire year for 118 species throughout the Western Hemisphere. Cornell Lab of Ornithology's All About Birds
Each dot represents a single bird species; the location represents the average of the population for each day of the year (see paper for a more precise explanation of the “average location”). Here’s a key to which species is which.
Cornell Lab of Ornithology – All About Birds, https://www.allaboutbirds.org/the-basics-how-why-and-where-of-bird-migration/
Audubon, “9 Awesome Facts about Bird Migration,” http://www.audubon.org/news/9-awesome-facts-about-bird-migration
The Spruce, “15 Fun Facts about Bird Migration,” https://www.thespruce.com/fun-facts-about-bird-migration-386434
BBC, “Fly like a bird: The V Formation Finally Explained,” http://www.bbc.com/news/science-environment-25736049
Wikipedia, “Bird Migration,” https://en.wikipedia.org/wiki/Bird_migration
Science, "Why Bird fly in a V Formation," http://www.sciencemag.org/news/2014/01/why-birds-fly-v-formation
National Geographic," Canada Goose," http://www.nationalgeographic.com/animals/birds/c/canada-goose/