The English language possesses a collection of imaginative collective nouns for groups of animals. This tradition of specialized terms, often dating back to the Late Middle Ages, gives us unique words for everything from a parliament of owls to a murder of crows. Applying this linguistic tradition to the hawk introduces a question about terminology that is deeply tied to the bird’s behavior. To fully answer what you call a group of hawks, we must look beyond a single word and examine the ecological context that dictates when and why these solitary raptors gather.
The Many Names for a Group of Hawks
The most common and accepted collective nouns for a group of hawks are “cast,” “kettle,” and “boil.” These words are used to describe a gathering of hawks, though each one carries a slightly different connotation based on the birds’ activity. The term “cast” is often used for a pair or a small group of hawks, particularly when they are resting or hunting in proximity.
The words “kettle” and “boil” are more specific and are frequently used interchangeably. A “kettle of hawks” refers to a large number of raptors circling together high in the air. This spectacle is a characteristic of hawk migration, where the birds congregate to efficiently use air currents.
How Hawk Behavior Determines the Name
The terms “kettle” and “boil” are directly linked to the hawks’ energy-saving strategy during long-distance migration. When the sun warms the ground, columns of rising warm air, known as thermal updrafts, are created. Hawks and other soaring raptors locate these thermals and circle within them, allowing the rising air to carry them upward without expending much energy flapping their wings.
This swirling, circular motion of dozens or even thousands of raptors riding the same thermal creates a distinct visual effect. The sight of the birds spiraling upward resembles the steam or bubbles rising from a pot of boiling water, which is the origin of the terms “kettle” and “boil.” Once the hawks reach the top of the thermal, they peel off and glide for miles, slowly losing altitude until they find the next thermal. This technique is important for species like the Broad-winged Hawk, which can form massive “kettles” during their southbound journey.
Why Large Gatherings of Hawks Are Uncommon
Outside of these specific migratory events, hawks are predominantly solitary predators. They are highly efficient hunters, and their survival strategy relies on hunting and flying alone. Most hawk species maintain individual territories to ensure a sufficient food supply, as large concentrations of raptors would quickly deplete local prey resources.
The only exceptions to this solitary nature are the temporary gatherings that occur during migration or when a localized food source is exceptionally abundant. For instance, the Harris’s Hawk is one of the few species known to hunt cooperatively in small family groups. Therefore, seeing a “cast” of non-migrating hawks, typically a pair, is a much more common sighting than observing a large, transient “kettle.” The specialized collective nouns reflect the fact that large groups are functional and temporary, not a daily social structure.