May is an explosive month and this year is no exception. As the landscape greens up and trees and flowers blossom, there is an explosion of worms, spiders and insects. And right on their heels come migratory birds.
Migratory birds nest in North America. Because the food (insects and pollen) these birds eat is not available in winter, they must migrate to South and Central America, Mexico and the Caribbean. As spring returns to North America, so do the birds as they follow their food sources to their breeding grounds.
Migratory birds include many species of songbirds (warblers, thrushes, tanagers and vireos), shorebirds (sandpipers, plovers and terns), some raptors (hawks, kites and vultures) and a few waterfowl species (teal).
Most long-distance migratory songbirds and shorebirds migrate at night when the air is cooler and calmer, and predators are few.
Birds that fly by soaring, like hawks and vultures, glide on rising currents of air. These soaring birds must migrate by day when the sun’s rays heat the earth, producing the rising air currents. Swallows, swifts and nighthawks also migrate by day because they feed on flying insects that are active during the day.
Different migratory birds rely on many different tools to navigate. Nocturnal migrants probably use the stars for compass direction. On cloudy nights, they may rely on other information. Other cues used by migratory birds include the earth’s magnetic fields, the location of the setting sun, landscape features and prevailing wind patterns.
The majority of migratory birds fly at airspeeds between 15 and 45 miles per hour, although both slower and faster flight speeds have been recorded. In general, larger birds fly faster than smaller birds.
Migration distances vary greatly between species and between individual birds of the same species. The shortest migrations are made by birds that breed in the southern United States and winter in Mexico or the West Indies, a trip that can be as short as a few hundred miles. Some of the longest migrations are made by shorebirds that nest in the arctic tundra of northern Canada and winter as far south as Tierra del Fuego (the southernmost part of South America), a one-way distance of up to 10,000 miles. Red Knots and white-rumped sandpipers are two species that make this remarkable journey.
Other birds that winter in South America, and thus travel great distances, include: common nighthawks; Swainson’s hawks; red-eyed vireos; purple martins; barn and cliff swallows; Connecticut, blackpoll and cerulean warblers; scarlet tanagers; and bobolinks. A round-trip migration distance for many of these species is as much as 13,600 miles.
Average daily migration distances understate the amazing capabilities of migratory birds. For instance, when traveling to South America in the fall, blackpoll warblers depart from New England and the southern coast of Canada on a nonstop flight that takes a minimum of 72 hours. That’s 2,000 miles in three days, or an average of 660 miles per day.
A one-way migration can take anywhere from several weeks to four months. The pace of migration tends to be faster in the spring, with the speed picking up as a bird gets closer to its breeding area. Typically, migration is accomplished in a series of flights lasting from several hours to several days. Between flights, birds make pit stops for resting and “re-fueling” which last anywhere from a day to a few weeks.
Despite all these amazing abilities, there are challenges that these birds cannot overcome on their own. Many species of migratory birds are declining. Problems include the loss of winter habitat, breeding habitat, and feeding and watering sites; pesticide use; and collisions with communications towers and brightly lit office buildings that can disorient birds. Although these are enormous threats, there are actions that citizens can take to help conserve migratory birds.
- Create Backyard Habitat: By planting native vegetation, homeowners provide badly needed food and cover for birds and other wildlife. Plant a variety of trees, shrubs and plants, and remember to offer a source of water.
- Try Shade-Grown Coffee: Winter habitats in Central and South America are also being altered. If you’re a coffee lover, consider buying shade-grown coffee. Coffee grown on clearcut plantations destroys critical winter habitat for migratory birds.
- Keep Cats Indoors: There are at least 68 million pet cats in the United States. Roaming cats kill birds. Studies have shown that birds make up 20–30 percent of cats’ prey. Cat owners can reduce the number of birds maimed and killed by simply keeping their cats indoors.
- Reduce Chemical Use: Birds are exposed to harmful pesticides intended to control specific pests. Bird die-offs have been linked to 40 active ingredients in pesticides. The chemical compounds most often implicated in bird kills are organophosphorus and carbamate insecticides. If possible, use low impact varieties of pesticides like dormant oils, insecticidal soaps or repellents free of organic solvents.
If you must use a pesticide, choose one targeted specifically for your pest problem. Contact your local cooperative extension service for more information.
International Migratory Bird Day Events
To focus attention on the nearly 350 migratory birds that travel between North America and South and Central America, Mexico and the Caribbean, the second Saturday in May is designated as International Migratory Bird Day. Here are some regional events:
- International Migratory Bird Day: 10 a.m.–3 p.m. May 6 National Wildlife Visitor Center Patuxent Research Refuge, Laurel, MD. Wildlife art, bird walks, live animals, wood duck display, migratory bird presentation, crafts for children. Contact: 301-497-5760
- Spring Fling/Birding Festival: 8 a.m.–4 p.m. May 6. Blackwater National Wildlife Refuge, Cambridge MD. Bird walk, eagle prowl, beginning bird walk, tours, puppet show, turtle race, children’s activities & crafts, education exhibits. Contact: 410-228-2677
- Migratory Songbird Festival: 7:30 a.m.–5:00 p.m. May 6, Bombay Hook National Wildlife Refuge, Smyrna, DE. Bird walks, talks, tours, boat trips, presentations, crafts, games, music, binocular use. Contact: 302-653-6872
- Migratory Songbird Festival: 7:30 a.m.–3 p.m. May 7, White Clay Creek State Park, Newark, DE. Bird walks, talks, tours, boat trips, presentations, crafts, games, music, binocular use. Contact: 302-653-6872
- Birds: May 12, Town of Cape Charles, VA. Musical & dance presentation celebrating birds. Contact: 757-331-2760.
- International Migratory Bird Day Festival: May 13. Eastern Shore of Virginia NWR, Cape Charles VA. Art show; children’s activities; workshops; presentations; field trips, including Fisherman Island walks, bird hikes, owl hoot, canoe & kayak trips. Registration required for trips; times vary. Contact: 757- 331-2760.
- International Migratory Bird Day Celebration: May 13, Eastern Neck National Wildlife Refuge, Rock Hall MD. Bird walk, children’s activities, guided bird walk, making bird feeders and bird houses and talks about migratory birds. Contact: 410-639-7056.
- Occoquon Bay National Wildlife Refuge, Woodbridge VA:
Bird Survey: 5 a.m.–noon, May13, Prince William Natural Resource Council will conduct a bird survey. Owling will start around 5 a.m.; regular bird counting at around 6:30 a.m. Sign up through the Council.
Restoration: 1–3 p.m. May 13. As part of the Audubon Refuge Keepers Program, Girl Scouts will restore erosion sites on the refuge and get a lesson on binocular use. Participation is by signup through the National Capital Council for Girl Scouts. Contact 703-490-4979.
- Chincoteague National Wildlife Refuge, Chincoteague VA:
Art: May 12, Reception, inspirational slide show & local artists’ display. Cost $5 per person.
Activities: 9 a.m.–4 p.m. May 13 & 14. Art contests, bird house & bird feeder construction, slide shows, speakers, guided bird tours, habitat walks, guided kayak tours. Contact: 757-336-6122.
- Orioles Migratory Bird Celebration: 7:05 p.m. May 27, Camden Yards, Baltimore. Information on migratory birds, including IMBD posters, fact sheets on backyard plants & bird feeding. Every fan will receive Backyard Bird Guides with descriptions of 12 birds that can be seen in the Baltimore area, their song, nest type & location, and types of trees or shrubs to attract them. Contact: Julie St. Louis, U.S. Fish and Wildlife Service, 703-358-1824.
Webs for Wings
Web users can learn get daily forecasts of bird movements, learn about the best bird viewing spots and find out how human activity impacts birds. Check out www.birdcast.org to see actual bird migrations throughout the mid-Atlantic region. Visit these other web sites for information about migratory birds and what you can do to conserve them.
- U.S. Fish & Wildlife Service International Migratory Bird Day: birds.fws.gov/imbd.html
- Smithsonian Migratory Bird Center: www.si.edu/smbc
- American Birding Association: www.americanbirding.org