The great spectacle of the autumn hike continues. There is nothing better than going out into the fields, seeing the migrants and saying goodbye to them until spring. But it’s also fun to read about migration to get a broader view of the phenomenon.
My favorite book about migration is Scott Weidensaul’s volume – “Living on the Wind: Across the Hemisphere with Migratory Birds” – published in 2000. Weidensaul describes astonishing examples of migration in his graceful, clear prose.
Bird migration is a popular research topic and our understanding has evolved significantly over the past 20 years. To test this new knowledge, Weidensaul has just published a new book, “A World on the Wing: The Global Odyssey of Migratory Birds”.
This new book is intended to complement rather than replace Volume 2000. âA World on the Wingâ is a series of chapters that describe the author’s own experience with current research. Some of the chapters are devoted to studies he is working on and others where he visits places to meet with the local researchers. In 10 chapters we get insights into new techniques and new knowledge from all over the world.
I assume that most readers will have the same envy as I do when I read about these fantastic migrations. Weidensaul takes us to China, Alaska, California, Argentina, Northwest India, Cyprus and other areas outside the borders – as well as more well-known places in the Northeast of the USA.
Conservation is a strong thread that holds all the chapters together. Substantial and even dire threats endanger migrants in some places. There are some conservation achievements that will brighten your day and give hope that threats to other migrants can be mitigated or eliminated.
We know the migration routes of many shorebirds that breed in the North American Arctic. We know we can see huge numbers of red knots in Delaware Bay in late May and hordes of semi-palmate sandpipers in the Upper Bay of Fundy in August and September. These birds overwinter in Argentina and Suriname.
Weidensaul describes conservation challenges for shorebirds that winter in the Pacific Ocean. This flyway, the East Asian-Australasian Flyway, is used by an estimated 8 million shorebirds each year.
This region is roughly shaped like an hourglass. The upper part of the hourglass where these shorebirds nest extends westward from Alaska to the eastern half of Russia. Most shorebirds nest on the arctic tundra.
The lower part of the hourglass, the wintering areas for these shorebirds, includes Indonesia, Australia, and New Zealand.
But the narrow center of the hourglass is the Yellow Sea along the Chinese coast. During migrations, the Yellow Sea mud flats are resting places for many of the migratory shorebirds, including the endangered sandpiper. There are only about 600 spoonbills.
As you can imagine, the pressure to develop along this narrow part of the Yellow Sea is enormous. Weidensaul leads us there and describes the efforts to preserve the Wadden Sea of ââthe Yellow Sea.
Recent advances in our understanding of bird migration have come in part from technology that was not available 20 years ago when Living on the Wind emerged. Satellite transmitters have been miniaturized so that small birds can be equipped with these tracking devices.
Geolocalizers are tiny devices that track light levels every few seconds. The time between dawn and dusk provides the latitude of an adapted bird every day, and the mean time between dawn and dusk provides the longitude. The birds have to be recaptured to download the data, but as many birds stay true to their nesting sites, the data is often restored.
Individual birds can now be tracked on weather radar. Check out birdcast.info to see the power of this approach.
In 2002, the Cornell Lab of Ornithology and the National Audubon eBird launched a data archive where bird watchers can record and share their sightings. The database is now approaching a billion records!
You will learn more about these new ways to monitor migration and many of the surprising results.
Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions below [emailÂ protected]