An Avian Migration Glossary

Definitions of Terms Used to Discuss Seasonal Bird Movements

Sep 22, 2008 Rosemary Drisdelle

The study of bird migration has a vocabulary used to refer to characteristics, behavior, and habitats of migrating birds. These terms have specific meanings.

Familiarity with the following terms makes material written about bird migration more accessible to the general reader:

Altitudinal migrant: a bird that migrates vertically, spending different seasons at different elevations, but in the same geographical location.

Breeding grounds: the habitat where a species nests and raises young.

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 the hours of daylight.

Dynamic soaring: a fight pattern where a bird glides with the wind until it drops too low, then climbs into the wing, turns and glides again.

Fall: when weather forces large numbers of migratory birds off course and they come down to rest somewhere that they do not normally occur.

Flyway: a route that many migrating birds of various species use while migrating. A flyway 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.

Irruption: when large numbers of one or more species of birds move together to new territory in search of food. Irruption is not true migration.

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 place 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.

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.

Star compass: the mechanism that allows a bird to find its way by the location of the stars.

Stopover: a place where migrating birds stop to rest, shelter and feed. These are typically places with abundant food supplies.

Sun 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 bird 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.

Sources:

Atlas of Bird Migration. Elphick, Jonathan ed. Buffalo: Firefly Books, 2007.

Firefly Encyclopedia of Birds. Perrins, Christopher ed. Buffalo: Firefly Books, 2003

"Migration of Birds." Lincoln, Frederick C., Steven R. Peterson, and John L. Zimmerman. U.S. Department of the Interior, U.S. Fish and Wildlife Service, Washington, D.C. Circular 16. Jamestown, ND: Northern Prairie Wildlife Research Center Online. (Version 02APR2002), 1998.

The copyright of the article An Avian Migration Glossary in Birds is owned by Rosemary Drisdelle. Permission to republish An Avian Migration Glossary in print or online must be granted by the author in writing.

Canada Geese at a Spring Stopover