Engaging Vignettes About the Private Lives of Birds
Bird expert Wenfei Tong tells us everything we want to know and much more.
Posted Sep 21, 2020
I'm pleased to offer this guest essay by Dr. Wenfei Tong, about her new and fascinating book, Understanding Bird Behavior: An Illustrated Guide to What Birds Do and Why.1,2,3
Birds are uniquely positioned to help us understand and cope with the impact of a global climate crisis. Their vulnerability makes them a good environmental early-warning system. Vast spaces linked by the long migratory journeys of many species help us to understand the global scale of climate change.
Birds’ visibility and charisma make them part of the solution. For no other group of living things do scientists have reams of recordings that stretch back for decades, almost all faithfully gathered by volunteers worldwide. In addition to revealing dramatic and depressing declines in bird numbers, these data present the chance to use technology to right some wrongs.
Most birds migrate at night, so biologists have started using existing weather radar technology to monitor large flocks. Some of the latest dual-polarization radar sends out two microwave beams instead of just one, allowing meteorologists to distinguish between rain, hail, and snow within a storm. Ornithologists are using the same technology to see details, such as which way a bird’s bill is pointed.
Another radar technique called NEXRAD catches birds as they take off for their migratory flights, which allows biologists to identify important patches of habitat that could be crucial rest stops. Doppler radar data allows scientists to reconstruct past migrations. Their findings are rather discouraging, documenting drops of 4 percent in migrant bird biomass every year.
Now, with citizen science platforms such as eBird, scientists can combine a multitude of recordings with information from radar, which shows how flocks move. This allows groups like the Cornell Lab of Ornithology to produce maps that animate the annual migrations of different bird species across continents. BirdCast, a joint project uses radar scans and eBird submissions to predict bird movements, just like a weather forecast, but for bird migrations. Scientists are also combining this information with satellite images showing light pollution levels to forecast the areas most likely to disorient migratory birds.
Conservationists are also working with governments to use these data to predict key flight paths, thereby minimizing migratory massacres from hazards such as light pollution or airplanes. Bird avoidance systems from many countries including Israel, Poland, and Germany, have collectively reduced collisions between birds and military aircraft by 45 percent.
eBird data has revealed that songbirds migrate very differently from the larger and more classically studied migrants such as shorebirds and waterfowl. Rather than going back and forth along the same route, these relatively diminutive travelers are more flexible. They also migrate in a loop, taking a different route on their journeys to and from breeding grounds, so as to take full advantage of tailwinds and to minimize headwinds.
Using computers to translate a variety of radar data, biologists from Cornell showed that shorter distance migrants that winter in the lower 48 states of America and breed north of the US-Canada border were less likely to return to breed than longer distance migrants that winter in South and Central America. This result is surprising because one would expect shorter journeys to contain fewer hazards.
Machine learning provides the next big step in understanding animal movements. By first training artificial intelligence programs on reams of bird recordings, much as one would train a human brain to distinguish birdsong from background noise, researchers are able to have computers translate sound recordings from bird-breeding grounds in the Arctic directly into arrival dates. This allows conservationists to know how migrant birds are responding to climate change without having to personally record or decipher anything. At present, the algorithm can distinguish birds from other noises such as the wind or machines. The next step is to train the computer algorithms to identify individual bird species.
Similar methods could be used to identify and predict migratory rest stops, breeding grounds, and the timing of bird movements, to inform governments and conservation groups about which places to concentrate on saving. Helping birds cope with climate is a global problem not just because climate change is a global phenomenon, but also because migratory birds link multiple nations by traveling through them. Just one weak link is enough to precipitate a systemic collapse.
Some conservation efforts are proving successful. The rare and elusive Bicknell’s thrush, which only breeds on mountaintops in New England, is now being protected at one of its key wintering grounds in the Dominican Republic. A massive outreach effort in northern India has turned what used to be a killing ground for Amur falcons into a sanctuary, allowing these charismatic little falcons to continue the longest-known migration of any raptor in the world. I have seen these beautiful birds roosting in Zambia, and they fly all the way from breeding grounds in China and Siberia. The key protected rest stop is in Nagaland where the falcons refuel on trillions of seasonal termites before flying 2,400 miles (3,862 km) across the Indian Ocean. The hope is that ecotourists will now flock to see the migrating falcons, rewarding the people of Nagaland for giving up a traditional mass hunt of the birds.
Most heartening is that the Chinese government has agreed to halt land reclamation in the Yellow Sea, which is a key rest stop for birds on the East Asian-Australasian flyway. Shorebirds from Siberia and Alaska migrate down this flyway to winter in Australia, and the mudflats along the coast of the Yellow Sea have provided a crucial place for migrating shorebirds to refuel. I have witnessed the impact of land reclamation on these mudflats over the last 20 years, as migrant shorebird numbers dwindle in the wetland nature reserve that I visit annually on my own migration back to Singapore. Habitat loss on the Yellow Sea coast has caused Far Eastern curlew numbers to plummet by 80 percent.
Birdwatchers can be amusing people. They cluster eagerly to see rare birds that get lost on migration and keep tabs on when and where they ever saw a bird. I am hopeful that we can continue to contribute collectively to accumulating big data that will help to save the birds we enjoy.
1) Excerpted from Understanding Bird Behavior: An Illustrated Guide to What Birds Do and Why by Wenfei Tong. Copyright © 2020, Princeton University Press. Reprinted by permission.
2) The books' description reads: Birds are intelligent, sociable creatures that exhibit a wide array of behaviors—from mobbing and mimicking to mating and joint nesting. Why do they behave as they do? Bringing to light the remarkable actions of birds through examples from species around the world, Understanding Bird Behavior presents engaging vignettes about the private lives of birds, all explained in an evolutionary context. We discover how birds find food, relying on foraging techniques, tools, and thievery. We learn about the courtship rituals through which birds choose, compete for, woo, and win mates; the familial conflicts that crop up among parents, offspring, and siblings; and the stresses and strains of nesting, including territory defense, nepotism, and relationship sabotage. We see how birds respond to threats and danger—through such unique practices as murmurations, specific alarm calls, distraction displays, and antipredator nest design. We also read about how birds change certain behaviors—preening, migration, breeding, and huddling—based on climate. Richly illustrated, this book explores the increasing focus on how individual birds differ in personality and how big data and citizen scientists are helping to add to what we know about them. Drawing on classic examples and the latest research, Understanding Bird Behavior offers a close-up look at the many ways birds conduct themselves in the wild.