American Kestrel Calls and Sounds

From its high-pitched “klee-Klee” calls to its long, drawn-out whines, the American Kestrel calls and sounds serve a specific purpose in its social life and survival strategies. This article explores the vocal repertoire of North America’s smallest bird of prey discussing the diverse range of sounds they produce, the contexts in which they are used, and the ways these sounds contribute to their communication, territorial defense, and mating. Let’s dive and see what I have put together.

American Kestrel repertoire of calls and sounds

The American Kestrel (Falco sparverius) has a relatively simple vocal repertoire compared to songbirds, but it uses its vocalizations effectively to communicate a variety of messages. Here’s a breakdown of the various types of vocalizations produced by the American Kestrel:

Klee-Klee-Klee Calls

This is the most common vocalization of the American Kestrel. It is a loud, excited series of 3-6 “klee!” or “killy!” notes lasting just over a second. Both the male and female kestrels use this call in various contexts, including:

Territorial defense: Males use the klee call to warn other males away from their territories. The klee-Klee calls are also used as an alarm to announce the presence of an aerial  predator, such as hawks and falcons. I have observed kestrels dive  bombing large hawks as they produce the Klee-Klee calls.

Courtship: Both males and females use the klee call during courtship displays. The dive and rise display is accompanied by constant Klee-Klee calls.

Communication between mates: Mates use the klee call to stay in contact with each other. They also use the Klee-Klee calls when they  meet each other after a period of separation.


Typical Klee-Klee Calls

TERRITORIAL CALL FROM A TREE TOP

COMMUNICATION BETWEEN MALE AND FEMALE

Whine calls

This is a long, drawn-out vocalization that can last for 1-2 minutes. Whine calls are used by both male and females during daily interactions and typically the following contexts:

Courtship: Both sexes use it to communicate during courtship displays and copulation.

Food exchanges: The female uses whine calls to prompt the male to deliver the food he brings to the nest while she is incubating.

Aggression: Kestrels may also use whine calls to display aggression towards other individuals.


TYPICAL WHINING CALLS

FEMALE WHINING CALLS BEFORE COPULATION

Begging quivering calls

This is a type of call that is similar to the whine call but it has a quivering quality to it. This type of call is produced only by the chicks.

In the nest: Nestlings begin to use begging quivering calls after the first week when they have the eyes open and are able to see well. Begging quivering calls get louder as chicks get older. 

  • Outside the nest: After fledging, chicks continue using the begging quivering call to solicit food from their parents. 
  • Contact calls: Fledglings use the quivering calls to keep in contact with each other.

Kestrel chicks lose the quivering whine call after they reach nutritional independence.

juvenile kestrels newly fledged


CHICK CALLS WHILE BEING FED

Situational or Interaction Calls

Situational or interaction calls are those specific to a situation or resulting from a specific interaction. These calls may have parts that resemble the typical calls but can incorporate unique or infrequently heard sounds. Additionally, these calls may combine parts of the typical calls.

Friendly interactions tend to result in soft calls including growls, hisses, and cackles. Aggressive interaction between adults, defense of the territory, and alarm calls are often louder, longer, and more excited.


MALE WITH FOOD CALLS THE FEMALE INSIDE DE NEST

EXCITED CALLS: MOBBING A RED-TAILED HAWK

Flight Calls

Does the American kestrel have songs

The American Kestrel does not sing in the traditional sense. They do not dedicate time to produce something that can resemble the song of a bird. These calls have either a staccato or whining quality and are used mostly in the context of interactions. 

Some individuals may string together a series of klee calls followed by whining calls and other vocalizations that resemble a song. But this usually results in the context of multiple types of interactions. 

Kestrel Communication by signals

In addition to the vocalizations mentioned above, American Kestrels also use a variety of visual and behavioral displays to communicate danger. These displays may include stooping flights, shallow wing-flapping glide, and tail-fanning.

American kestrels do a characteristic head bobbing when they try to have a better look at something. A nervous head bobbing may be a way to communicate the presence of potential prey or minor approaching risks.

Does the American Kestrel have the ability to learn and imitate calls or other vocalizations?

American Kestrels have an innate repertoire. Their core vocalizations are genetically preprogrammed. This means that physiologically the sounds  they produce are the only sounds that their brains and syrinx are able to produce.  

The ability of birds to learn and imitate the songs and calls of other birds varies greatly across different species. This ability is rooted in several physiological reasons. Among the more evident are the brain structure and syrinx complexity of a bird.

Brain Structure

Birds capable of vocal learning possess a specific neural pathway in their brains called the “vocal learning pathway”. This pathway connects the auditory areas, where sounds are processed, to the vocal motor areas, responsible for sound production. This connection allows them to analyze and learn new sounds and then reproduce them accurately.

Syrinx Complexity

The syrinx, the vocal organ of birds, also plays a crucial role. Birds with intricate syrinx structures, with multiple sets of muscles and membranes, have greater control over their vocalizations and are more adept at mimicking sounds.

Many songbirds, such as mockingbirds, warblers, and finches, are renowned for their ability to learn and imitate a wide variety of sounds. They possess sophisticated vocal learning pathways and intricate syrinx structures, allowing them to achieve remarkable vocal feats.

Hawks and falcons like the American kestrel have limited or no vocal learning ability. Their simpler vocal organs and brains lack the necessary adaptations for complex sound production and mimicry.

Does the American Kestrel have regional vocal dialects?

Anecdotal observations, and research suggest differences in kestrel calls from different regions, particularly in the pitch and frequency of their “klee” calls; the most common kestrel call. 

Klee klee calls of an American kestrel recorded in the Country of Peru. This call es rather similar to the calls of American kestrels in North America.

Studies have analyzed recorded kestrel vocalizations from various locations, revealing subtle variations in acoustic parameters like frequency modulation and call duration. Differences in American Kestrels calls across their wide range appears to be associated with genetic variation and population differentiation, which could be reflected in vocal dialects.

References

  • Johnsgard, P. 1990. Hawks, Eagles, and Falcons of North America. United States: Smithsonian Institution.
  • Smallwood, J. A. and D. M. Bird (2020). American Kestrel (Falco sparverius), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

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