- Migratory Fly-way System- Simple Overview
- The Pacific Fly-way
- The Central Fly-way
- Mississippi Fly-way (Primary and Secondary route map)
- Atlantic Fly-way (Primary & Secondary route map)
- Migration links (follow tagged birds)
- General Terms When Discussing Migration
 The migratory fly-ways, or routes, utilized by birds are numerous and cover most of North America in one way or another. Some of the fly-ways are simple and recently traced, while others are divergently complicated. Many factors go into Differentiating which fly-way a particular species will take; distance traveled, geographic location, start of migration, speed of travel, the location of breeding and wintering grounds all contribute to migratory diversity. No two species follow the same fly-way. Even species with the same distribution may travel along different geographic fly-ways. With four primary migratory fly-ways recognized, the Pacific, Central, Mississippi, and Atlantic, we are going to focus on the Pacific and Central Fly-ways in relationship to Montana and the surrounding states.
Migration is generally recognized as a North - South movement, with heavier concentration of birds following the coast lines, mountain ranges and major river valleys. It may be said generally that the Fly-ways conform very closely to major topographical features when these features are in the general direction of the fly-ways traveled. It so happens that this line of thinking work in North America where the coasts, mountain ranges, and larger river systems share a North - South aspect.
The term fly-way is more of a descriptive term than an absolute. While the term fly-way has come to have an administrative meaning in Federal and State wildlife programs, migration route, migration corridor may still be heard or used from time to time as a descriptor. Migration fly-ways may be defined as lanes of travel to and from particular breeding grounds used by different species, but are recognized as possessing broader areas in which related migration routes are associated or blended into a geographic region. Think of a fly-way as a wide bird highway, with a lot of exit and entrance ramps to and from rest stops.
In relationship to the North American fly-ways, the confines, or boarders, are not always sharply defined, except along the coast, and in breeding (North), and wintering (South) territories there is recognized and understood overlapping of the boundaries. In Panama, parts of all four flyways merge into one and great kettles of raptors may be seen utilizing the thermal updrafts that rise above the jungle.
 The Pacific fly-way is made up of Western Arctic, including the Aleutian Islands, the Rocky Mountains, and the Pacific coast regions of Canada, the United States down into Mexico to the south where it blends into the other fly-ways into Central and South America, as previously mentioned.
The Pacific fly-way defines itself across the Alaska Peninsula, the Gulf of Alaska and down the coast of British Columbia, Washington, Oregon and California. The Pacific coast fly-way is used by Artic Terns, gulls, ducks, and other assorted waterfowl which breed in Alaska. The delta region of the Yukon River, which is used by a great many mammals in Alaska, is a breeding ground for many species of waterfowl and thus marks the northern end for some avian species that utilize the Pacific fly-way along the coast line for most of all of their migratory movement.
The longest and most sensitive section of the Pacific fly-way is the section starting in North-eastern Alaska and cutting through the interior. Most of the birds (predominantly waterfowl) that travel the western U. S. section of this fly-way, originate from the Mackenzie and other rich, lush Alaskan interior valley regions. Starting in Alaska, Yukon and Mackenzie sections, the Pacific fly-way runs south through western Alberta, paralleling the eastern foothills of the Rocky Mountains. The Pacific fly-way branches and while large flights of birds continue southeast and merge into the Central and Mississippi fly-ways. Others turn southwest and travel across northwestern Montana and the panhandle of Idaho, following along the Snake and Columbia River valleys then head south across central Oregon to the valleys of California. Wintering birds can be found in California from the Sacramento Valley, south to the Salton Sea, and the tidal marshes near San Francisco Bay.
The southern over-winter movement of migratory land birds following the Pacific fly-way into the United States, extends throughout the interior of California down to the mouth of the Colorado River and onto the winter quarters along the Baja peninsula and western Mexico.
 Here in Montana, we are more familiar with the Central fly-way, in which we live. The Central fly-way is relatively simple and straight forward with the majority of the birds that follow its path making direct north - south journeys from breeding grounds in the North to over-wintering grounds south. The Pacific fly-way has its origin along the northwest Arctic coast, to where it merges with the Mississippi fly-way to the east (the Missouri River being the boundary). Along the south-eastern side, it runs through western Missouri, Arkansas and Louisiana, thus following the coast to Gulf coast of Mexico, south into South and Central America, the same topographic characteristics that sends hosts of migrants down the Mississippi fly-way, but farther south, in Canada, the western boundary follows closely the eastern base of the Rocky Mountains (“The East Side”). In western Montana, however, the continental divide is crossed (Check out Raptor View and Rob’s work with Golden Eagles, www.raptorview.org) with the fly-way passing through the Great Salt Lake Valley, (its western boundary) which is an important breeding area for waterfowl at the northern end of Great Salt Lake, Utah, and then meanders south to cross the Mexican tablelands. The Pacific fly-way is commonly referred to as the fly-way of the Great Plains as it encompasses the entire region lying between the valley of the Mississippi River and the Rocky Mountains, the principal heart-land, wheat producing,region of North America from Canada, south through the U. S.
To look at, and discuss some of these fly-ways and the activities that actually take place, you can look up;
Raptor View Research Institute
Falcon Research Group (FRG)
The Canadian Peregrine Foundation
Take a minute and see which birds are following which fly-way. Ask yourself why do particular birds follow certain tracks, and what does all this travel mean to the over all health to the birds.
The following terms are most often used when discussing migration, and bird / flock activities during migration.
- Altitudinal migrant: a bird that migrates vertically (mountains, to river bottoms)
spending different seasons at different elevations, in the same
geographical location.
- Breeding grounds: the habitat where a species nests and raises young.
- Celestial (star) compass: the mechanism that allows a bird to find its way by the
location of the stars.
- Circadian rhythm: an internal clock that governs a bird’s daily cycle.
- Circannual rhythm: an internal clock that governs a bird’s yearly life cycle, triggering
migration, breeding, etc.
- Diurnal migration: migration during daylight hours.
- Dynamic soaring: a fight pattern where a bird glides with the wind until it drops too low,
then climbs into the wind, turns and glides again.
- Fall: when weather forces large numbers of migratory birds off course and they come
down to rest somewhere they do not normally occur.
- Fly-way: a route that many species of birds use while migrating. A fly-way may be
defined by a seacoast, a mountain range, a river system, an ocean current, or
some other significant geographical feature that channels birds in flight.
- Great Circle routes: flight paths that represent the shortest distance between two points
on the globe.
- Leading lines: physical features of the earth such as mountain passes, islands, and
narrow necks of land that large numbers of birds must pass through or
stop at.
- Magnetic compass: the mechanism that allows a bird to navigate by locating magnetic
north.
- Migrant: a migrating bird.
- Molt migration: a migration to a specific area or region where the birds molt.
- Nonstop migrant: a bird that completes its entire migration without stopping along the
way. Some nonstop migrations cover thousands of kilometers and
span days.
- Nocturnal migration: migration during the hours of darkness (night).
- Partial migration: when part of a population of birds in a specific area migrate while the
rest remain resident year round. Sometimes, it is the juvenile birds
that migrate.
- Pineal gland: a gland in the brain that controls the circadian rhythm of bird species.
- Roost: a large number of birds, usually the same species, sleeping together in the same
place.
- Staging post: stopovers where large numbers of migratory birds traditionally pause to
feed before moving on. The best known staging posts are those used by
large birds such as cranes.
- Stopover: a place where migrating birds stop to rest, shelter and feed. These are typically
places with abundant food supplies.
- Solar compass: the mechanism that allows a bird to find its way by the location of the
sun.
- Thermal current: warm air rising into the atmosphere from the ground. Thermals are
usually strongest in the morning.
- Thermal soaring: when a bird uses the rising air of a thermal to lift it high in the air. The
birds can then glide down to the bottom of the next thermal and rise
again.
- Wintering grounds: the territory where a bird species spends the winter months.
- Zugunruhe: a restlessness observed in birds as the time to migrate approaches.
We also want to thank Google, Google Earth for their maps
www.google.com
www.googleearth.com
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