A World on the Wing is a fantastic collection of statistics and anecdotes that mesh into a captivating globetrotting adventure. “The Global Odyssey of Migratory Birds”–the book’s subtitle–is a fitting description for its contents. Author Scott Weidensaul fills the book with anecdotes from his decades of adventures observing, banding, and helping save migratory birds. Below, I share my thoughts on the book and some of its highlights.

Biggest Takeaways

Two of my biggest takeaways from A World on the Wing were how much we still don’t know about birds and how difficult it is to study them. For example, of over 4,000 Gray-cheeked Thrushes banded in Alaska, only three were ever recaptured. However, big advances in miniaturizing tracking equipment is revolutionizing ornithologists’ ability to study migratory birds. Even more fascinating was how it’s now understood that birds navigate: by quantum entanglement. Yes, that physics phenomenon that even incredibly smart people have a hard time wrapping their heads around and Albert Einstien referred to as “spooky action”. The author does a good job at making how it works about as clear as you could reasonably expect in the second chapter.

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Fascinating Facts

Besides the whole quantum entanglement thing that blew my mind, the early chapters are replete with interesting tidbits about migratory birds. For example, birds quickly bulk up their muscles before migrating without exercising. How they do it is not understood, but with further perhaps we could do the same. (I sure hope so!)

I was aware that swifts are able to shut down half of their brain at a time to sleep as they fly for months on end. However, A World on the Wing goes into much more specific examples and how it works and that not only swifts do this. Other birds like frigatebirds–the only birds whose feathers weigh more than their skeleton–and other pelagic birds also do this. This phenomenon has also recently been discovered in some mammals.

Sadly, we don’t get Red Knots very often in Costa Rica. They detect food in a way that is unique among animals. Their bill moves quickly up and down through wet sand, looking for clams. As they probe in the sand, it creates shock waves that reflect back to the tip of its beak. It’s like how bats use echolocation, but they do it by making shockwaves in wet sand and sensing the way those waves reflect back.

Blue Jays–some the smartest of birds out there–will follow researchers to find out the location of nests they can raid. One researcher is quoted in the book saying “I fake finding nests a lot, doing all the things down in the grass I would do if there was really a nest, so the jays don’t know when I have a real one. It’s kind of funny—I’ll look back, and the jay will actually duck behind a tree trunk to hide from me.”

Migratory Feats

I want to quote from the book here as I thought this was a fantastic explanation of the incredible feat that is bird migration:

Actually, referring to the flight as a marathon does the birds a considerable disservice. Theunis has noted that an elite human athlete, performing at maximum exertion—a male Tour de France cyclist in mid-race is a good example, he says—is operating at about five times his base metabolism. That seems to be the upper limit for sustained exercise by even the fittest, most highly trained human. A shorebird, on the other hand, is working at a rate eight or nine times its base metabolism, and is doing so for days at a stretch without food, water, or rest.

Weidensaul, Scott. A World on the Wing: The Global Odyssey of Migratory Birds (p. 40). W. W. Norton & Company. Kindle Edition.

We still don’t fully comprehend the breadth of the feats of migration that some birds undertake. Here are a few of the most incredible ones mentioned in A World on the Wing:

  • Some species of shearwaters travel more than 46,000 miles (74,000 km) per year.
  • Bar-tailed Godwits make the longest known non-stop flight of any landbird. They travel 7,200 miles (11,500 km) over eight or nine days across the Pacific from Alaska to New Zealand.
  • Common Swifts stay in the air for ten months at a time. Based on how far tracked birds have traveled, and the oldest banded bird having survived 18 years, they may travel in excess of four million miles (6.4 million km) in their lifetime!
  • Wandering Albatrosses will fly 74,000 miles (119,000 km) between breeding seasons every two years. During this time they circumnavigate Antarctica two or three times without ever seeing land.

Conclusion

I thoroughly enjoyed reading A World on the Wing and highly recommend it to anyone interested in birdwatching. If you are a statistics nerd like me, the early chapters will be your favorites. If you prefer more of a narrative style, documenting adventures around the world, the later chapters will be more your cup of tea.