The fading miracle of migration

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Photo courtesy Pepper Trail
Migrating snow geese near Ashland, Oregon this fall.

By Pepper Trail | OVERVIEW Columnist

Over the past few weeks, dozens of red-headed vultures have been circling on thermals above my home in Oregon, preparing to fly south into California. Not long ago, I saw a Late Monarch butterfly passing high above, its orange wings glowing against the blue sky.

These are examples of the great migratory movements that animate the West each spring and each autumn.

Long-distance migrations of seemingly fragile monarch butterflies are among nature’s most incredible phenomena, with eastern populations wintering in large numbers in a small refuge in Mexico and western populations in a few sheltered spots along the California coast.

Migration is central to the lives of many wild animals of great public interest and economic importance, from salmon and waterfowl to large mammals like pronghorns and elk. Almost everyone who is sensitive to the natural world looks forward to a migratory milestone, whether it’s the arrival of the first robin of spring or the start of duck hunting season.

Thanks to advances in technology and data collection, this is a golden age for migration research. Radar helps document the scale of animals on the move: on a recent night, for example, an estimated 5.4 million birds were in the skies of Oregon.

The eBird citizen science database, coupled with advances allowing the detection of signals from light tags attached to migrating animals, has provided migration maps of astonishing specificity. For an example with red-headed vultures, go to https://tinyurl.com/mtndawtm.

At the same time, we are also coming to understand the many threats to migration. The drastic declines of Pacific salmon are all too well known. Elk and pronghorn face ever-increasing obstacles posed by highways, roads to access and extract fossil fuels, and other developments in the landscape.

But what happens to the migrating birds really tells the story. Based on multiple lines of evidence, scientists have concluded that 2.9 billion — yes, billion — breeding adult birds have been lost in the United States since the 1970s. That’s one-third of the total population of birds of the United States.

Of these 2.9 billion, 86%, 2.5 billion, are migratory species. Although bird declines in the western part of the country are less severe overall than in the east, many of our familiar migrants are showing dramatic reductions, including the rufous hummingbird, down 60%; common nighthawk, 58%; band-tailed pigeon, 57 percent; Lewis Peak, 67%; and evening grosbeak, 92%.

Why does this happen? Habitat loss is the main problem for many species, especially grassland birds. For example, between 2018 and 2019 alone, 2.6 million acres of grassland in the Great Plains were converted to row crops. It is a larger area than Yellowstone National Park. Loss of winter habitat in Mexico and Central America also threatens many species.

Human constructions, from power lines to wind turbines to oil wells, increase the risk of migration for birds. The biggest hazard may seem trivial, but it’s ubiquitous: windows. Window collisions are estimated to kill one billion birds in this country each year. Brightly lit skyscrapers are also a threat to songbirds, most migrating at night.

Climate change adds to the threats to migratory species. In addition to general effects such as widespread drought in the West and melting permafrost in the Arctic, climate change may blur the relationship between the timing of migration and the availability of food resources. Hungry migrants may arrive in the spring and find that the peak of insect abundance has already passed.

Fortunately, there are many things each of us can do to help migrating birds. First, advocate for the preservation of bird habitats – and create your own by planting native fruiting and flowering plants on your land.

Second, take steps to reduce bird collisions with your windows. Many solutions are available, including “Zen windproof curtains”: cords of light suspended in front of the window. For DIY instructions and more, go to https://tinyurl.com/2hf558nj. And keep your cats indoors, because loose cats wreak havoc on birds.

Finally, support organizations that defend birds and their habitats or promote research on migratory birds, such as the National Audubon Society, American Bird Conservancy, and Cornell Laboratory of Ornithology.

Together we can save the lives of millions of birds and ensure their incredible migratory journeys never end.

Pepper Trail is a contributor to Writers on the Range, writersontherange.org, an independent nonprofit dedicated to stimulating lively conversation about the West. He is a naturalist and writer in Oregon. The views expressed do not necessarily represent those of SUN.

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