Happy Bird Day to You!
By Jane Koska
It’s World Migratory Bird Day! Created in 1993 by the Smithsonian Migratory Bird Center and now observed on the second Saturday in May, World Migratory Bird Day is a celebration of the billions of birds that migrate worldwide. WMBD 2022 will be observed on May 14.
The Cornell Laboratory of Ornithology defines migration as an annual, large-scale movement of birds between where they breed in summer and their nonbreeding (winter) grounds. In the Northern Hemisphere, spring brings a northward migration as species return from their winter homes in the tropics to northern regions where they raise their young. Several factors contribute to triggering migration, including changing day length, temperatures, and food supplies. While scientists still don’t fully understand how birds navigate, it seems to be a combination of using the sun and stars as a compass, sensing the earth’s magnetic field, and even using landmarks.
Many of us associate migration with V-shaped flocks of geese flying south in the fall, but geese are just one example of migratory birds. (But note that as lawns, parks, and golf courses have proliferated, some Canada geese have become non-migratory, breeding and overwintering in the same area.) Of the more than 650 species of North American breeding birds, more than half are migratory. Long-distance migrants range in size from the tiny ruby-throated hummingbird, weighing less than half an ounce, to the elegant tundra swan with its more than five-foot wingspan. Songbirds like the Baltimore oriole and birds of prey like the osprey all migrate south in the fall and north in the spring.
Migration is a truly amazing natural phenomenon. That tiny hummingbird visiting a backyard feeder in summer may have flown non-stop across the Gulf of Mexico during its migration. Tundra swans winter on the Chesapeake Bay and raise their chicks in the remote Arctic—as far north as they can go while still being on solid ground. The Cornell Lab estimates that an osprey may log more than 160,000 migration miles during its 15-to-20-year lifetime. In fact, one osprey tracked by satellite transmitter flew 2,700 miles—from Martha’s Vineyard to French Guiana—in just 13 days.
The theme of WMBD 2022 is “Dim the Lights for Birds at Night,” which refers to the growing threat of light pollution to migratory birds. Migrants typically fly at night when weather is calmer and threats from predators are fewer. However, lights left on at night attract and disorient migrating birds. Many collide with windows and are seriously injured or killed. Tall buildings are also a major daytime cause of mortality to birds that don’t recognize exterior glass as an obstacle.
Lights Out DC is an all-volunteer effort of City Wildlife, a wildlife rescue and rehabilitation organization in Washington. In early mornings during spring and fall migration, volunteers walk a route through a small area of downtown DC looking for birds on sidewalks and streets. In their ten-year report, Lights Out DC reported that volunteers found on average 300 birds per year, 84 percent of which were dead or died within hours.
But light pollution isn’t the only threat birds face, whether they migrate or not. Loss of habitat, changing weather patterns, fewer native plants, exposure to pesticides, pollution like single-use plastics, and clear-cutting of tropical forests are among the factors that put birds at risk. The Smithsonian Migratory Bird Center estimates that up to 1 billion birds die each year after flying into closed windows—including those in residences—in the U.S. and Canada alone.
There seems to be a consensus, however, that the number one threat to birds is from outdoor cats. A frequently cited estimate of the number of birds killed annually in the U.S. by domestic cats is 2.4 billion—yes, billion with a “B.” Feral cats can’t be blamed for all these losses. When owners let their pet cats roam outside, those cats are very likely to hunt. Not only do outdoor cats put birds at risk, but the cats themselves are at an increased risk of contracting disease, being injured, or worse.
And dog owners aren’t off the hook either. Curious dogs can disturb birds that are feeding and resting, both of which are vital during the stress of migration and breeding. Obviously, off-leash dogs are the biggest concern, but at least one study shows that a hiker with a dog is more disruptive to birds than a hiker alone. According to Audubon, dogs running loose on the beach are a particular problem. Seabirds and shorebirds nest on the sand, sometimes in large colonies. A dog can disturb the entire colony, potentially causing the whole group to abandon their nests, eggs, or chicks.
In addition to being a responsible pet owner, what can you do to help birds? The Smithsonian Migratory Bird Center and other experts recommend several things. Use fewer pesticides and herbicides. Plant native plants, which are natural food sources, in your garden and yard. Put decals on windows. Hang bird feeders with a variety of food sources. Provide water. Participate in citizen science projects, like Lights Out DC and eBird (Cornell’s online database of bird observations).
Migratory birds provide vital benefits to the environment, including pest control and pollination. Millions of birders (formerly called birdwatchers) and bird enthusiasts get a great deal of enjoyment from observing birds in their natural habitats and back yards. And everyone can appreciate birds’ lovely songs, beautiful colors, and graceful flight. Every day—Migratory Bird Day or not—should be a happy bird day.
About the Author: Jane Koska would be a better birder if birds didn’t get up so early in the morning. She lives in Washington, DC, with two very fluffy – and indoor – tabbies.
World Migratory Bird Day: https://www.migratorybirdday.org/
Cornell Laboratory of Ornithology: https://www.birds.cornell.edu
Smithsonian Migratory Bird Center: https://nationalzoo.si.edu/migratory-birds
Cornell’s All About Birds: https://www.allaboutbirds.org
American Bird Conservancy’s “Cats Indoors” program: https://abcbirds.org/program/cats-indoors/
Lights Out DC: https://citywildlife.org/programs/lights-out-dc