A
kettle is a term that
birdwatchersBirdwatching or birding is the observation and study of birds with the naked eye or through a visual enhancement device like binoculars. Birding often involves a significant auditory component, as many bird species are more readily detected and identified by ear than by eye...
use to describe a group of birds wheeling and circling in the air. The kettle may be composed of several different species at the same time. Nature photographer M. Timothy O'Keefe theorizes that the word derives from the appearance of birds circling tightly in a
thermal updraftA thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection. The Sun warms the ground, which in turn warms the air directly above it....
"like something boiling in a cauldron." Osprey-watcher David Gessner, however, cites a Pennsylvania lowland called the Kettle ("der Kessel" in
Pennsylvania DutchThe Pennsylvania German language is a variety of West Central German possibly spoken by more than 250,000 people in North America...
), near
Hawk MountainHawk Mountain is a mountain ridge, part of the Appalachian Mountains, located in central-eastern Pennsylvania near Reading and Allentown. It is a part of the Blue Mountain Ridge. It is primarily known as home to the Hawk Mountain Sanctuary....
, as the source of the term.
In some species--e.g.
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A
kettle is a term that
birdwatchersBirdwatching or birding is the observation and study of birds with the naked eye or through a visual enhancement device like binoculars. Birding often involves a significant auditory component, as many bird species are more readily detected and identified by ear than by eye...
use to describe a group of birds wheeling and circling in the air. The kettle may be composed of several different species at the same time. Nature photographer M. Timothy O'Keefe theorizes that the word derives from the appearance of birds circling tightly in a
thermal updraftA thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection. The Sun warms the ground, which in turn warms the air directly above it....
"like something boiling in a cauldron." Osprey-watcher David Gessner, however, cites a Pennsylvania lowland called the Kettle ("der Kessel" in
Pennsylvania DutchThe Pennsylvania German language is a variety of West Central German possibly spoken by more than 250,000 people in North America...
), near
Hawk MountainHawk Mountain is a mountain ridge, part of the Appalachian Mountains, located in central-eastern Pennsylvania near Reading and Allentown. It is a part of the Blue Mountain Ridge. It is primarily known as home to the Hawk Mountain Sanctuary....
, as the source of the term.
Kettling and migration
In some species--e.g. the terns of Nantucket--kettling behavior is evidently a way of "staging" a flock in readiness for migration. Pre-migrational turkey vultures kettle by the hundreds in the thermals that rise over
Vancouver IslandVancouver Island is a large island in British Columbia, Canada, one of several North American regions named after George Vancouver, the British Royal Navy officer who explored the Pacific coast of North America between 1791 and 1794....
before they venture across the
Strait of Juan de FucaThe Strait of Juan de Fuca is a large body of water about long forming the principal outlet for the Georgia Strait and Puget Sound, connecting both to the Pacific Ocean...
toward Washington State. At Hawk Mountain, broadwinged hawks form kettles in September before flying south. Kettling apparently serves as a form of avian communication—an announcement of imminent departure—as well as a way of gaining altitude and conserving strength. Because of this they kettle a lot.