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What range maps tell us. Four major U.S. flyways Atlantic Mississippi Central Pacific …but this is larger than the U.S.
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Four major U.S. flyways • Atlantic • Mississippi • Central • Pacific • …but this is larger than the U.S.
Migration is the seasonal movement of birds between breeding and winter feeding grounds. Some birds make a slight seasonal shift (known as invasions, dispersal or irruptions) due to weather or food availability. True migration is a bi-annual, movement that can span countries, hemispheres, even continents and cover as many as 9000 miles. Massachusetts is unique in that it represents the northern breeding grounds for neotropical songbirds, the southern wintering grounds for sparrows, sea ducks, and owls, and a layover for long distant migrants like shore birds. The timing of migration is dictated by daylight hours and food availability, not necessarily weather or temperature. Birds have developed specialized nesting habitats and often migrate thousands of miles to return to the same acre of hay field, boreal forest, or marsh to breed each summer. While we consider the birds of Massachusetts to be “our birds,” most are international travelers who spend a part of each year in a dozen countries from Canada to Argentina.
“On wingspans of 20 inches, red knots fly more than 9,300 miles from south to north every spring and repeat the trip in reverse every autumn, making this bird one of the longest-distance migrants in the animal kingdom.” U.S. Fish and Wildlife June March September December
How birds navigate • land forms • celestial navigation • magnetism • sixth and seventh senses?
Rivers Mountains Coastlines
Celestial Navigation Most songbirds migrate at night and rest and eat during the day. Flying between 20 to 30 mph, night-migrating songbirds fly below 2000 feet though some can fly as high as 6,500 feet. Certain species of geese and cranes have been sighted clearing Mt. Everest at over 29,000 feet. Biologists have found that birds use the position of the sun, moon, and stars to help them navigate. A chemical reaction triggered by evening light registering in the green and blue spectrum may prompt a desire to depart.
Magnetism Birds have particles of the metallic compound, magnetite in their nasal cavity. Biologist believe that this is drawn to the magnetic fields of the earth, giving birds literally, an internal compass. Amazingly, birds that migrate over the equator must accommodate for the change in polarity.
Humans catching on Hibernating Swallows Caught by Fishermen, from Olaus Magnus' (1555) "History of the Northern People"
Night migration, radar and “angels” April 28, 2004, at 23:02 Picked up by NexRAD and Doppler
Audio monitoring Common Yellowthroat Black and white Warbler From http://oldbird.org
What you can do to help protect migrating song birds "Over increasingly large areas of the United States spring now comes unheralded by the return of birds, and the early mornings are strangely silent where once they were filled with the beauty of bird song.” Silent Spring by Rachel Carson 1962
support land conservation – fight habitat loss by supporting conservation trusts, your local Audubon sanctuary, or international efforts to protect land • vote with your stomach by eating locally grown, organic food – pesticides and mono-crops effect all birds, especially migratory, through exposure to toxicity and habitat loss • drink shade grown coffee – support tropical forests throughout central and south America • turn off outside lights during spring and fall and support city wide “Lights Out” initiatives – lights can cause window strike kills and disorientation • let your lawn “go wild” – avoid pesticides and cultivate native plants, creating habitat and food • keep house cats indoors (cats are responsible for over 1,000,000 U.S. bird kills annually)
Resources Web Resources • All About Birds (Cornell Lab of Ornithology) • The Voice of Audubon (MassAudubon.org) • Audio monitoring (oldbird.org) • Bird Atlas (www.pwrc.usgs.gov/bba/)
Birds of the forest and woods
