The sparrow hawk, known scientifically as the American kestrel (Falco sparverius), holds the title of the smallest and most prevalent falcon in North America. Exhibiting a slight variation in size due to subspecies and gender, these birds can weigh anywhere from as light as a blue jay to as heavy as a mourning dove. Despite its North American dominance, the American kestrel’s habitat extends further south into South America. Over time, this bird has flourished and branched out into 17 distinct subspecies, each one uniquely suited to thrive in different environments and habitats across the Americas.
In the world of birds of prey, the American kestrel holds the title of the smallest raptor in all of America according to traditional classification. It’s worth noting that the American kestrel displays sexual dimorphism, meaning that the males and females have differing appearances. However, it’s important to mention that there is some similarity in the coloration of their plumage. In terms of size, the American kestrel typically ranges from 22 to 31 cm (8.7 to 12.2 in) in length, while its wingspan measures approximately 51–61 cm (20–24 in).
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The female kestrel is larger than the male, although its size difference is not as significant as larger falcons. In a specific subspecies, the female kestrel is typically 10% to 15% larger. Generally, the kestrels in more northern regions tend to be larger in size. For instance, a large female kestrel in the northern hemisphere can be about twice the size of a small male kestrel in the southern regions. The average weight of a male kestrel ranges between 80 and 143 grams (2.8-5.0 oz), while the female kestrel weighs between 86 and 165 grams (3.0-5.8 oz). In terms of measurements, the wing bone’s length is approximately 16 to 21 centimeters (6.3-8.3 in), the tail measures around 11 to 15 centimeters (4.3-5.9 in), and the tarsus measures between 3.2 and 4 centimeters (1.3-1.6 in).
Regarding vocalizations, the American kestrel produces three basic sounds – the “klee” or “killy”, the “whine”, and the “chitter”. The “klee” sound is typically conveyed as a rapid sequence, such as klee, klee, klee, klee, when the kestrel is agitated or excited. This vocalization is utilized in various situations and can be heard from both male and female kestrels. Nonetheless, the larger female kestrels tend to have deeper voices compared to the males. On the other hand, the “whine” call is mainly associated with feeding but can also be emitted during copulation.
Ecology and behavior:
American kestrels can be observed in various environments such as grasslands, meadows, deserts, and other open or semi-open areas. Interestingly, they are not confined to rural areas alone, as they can also thrive in urban and suburban regions. In order to establish a comfortable habitat, kestrels must have access to perches for resting and observing, ample open space for hunting, and suitable hollows for nesting purposes.
The range of living conditions that the American kestrel can adapt to is quite remarkable. They are found in a variety of environments, from the Arctic Circle to the tropical regions of Central America. These resilient birds can even survive at extremely high elevations, up to 14,800 feet in the Andes Mountains. You can spot them anywhere from northern Canada and Alaska to the southernmost point of South America, in a place called Tierra del Fuego.
It’s worth noting that the American kestrel is the only kestrel species found in the Americas, even though its classification is not entirely accurate from a genetic standpoint. Although it is primarily found in the Americas, it has been seen as a vagrant in other parts of the world, such as the UK, Denmark, Malta, and the Azores.
When it comes to feeding, the American kestrel has a versatile diet. They mainly consume small animals like grasshoppers, crickets, butterflies, moths, dragonflies, beetles, lizards, mice, voles, shrews, frogs, and small birds. Interestingly, there have also been reports of kestrels killing scorpions, snakes, bats, and squirrels. This diverse diet allows them to thrive and maintain high population densities. Their primary hunting strategy involves perching and patiently waiting for their prey to come within reach.
Overall, the American kestrel is a fascinating bird that has adapted to a wide range of habitats and has a diet that encompasses various small creatures.
The bird is commonly observed on roadsides or in fields, perched on various objects like trees, power lines, or fence posts. It utilizes kiting as a hunting technique, where it hovers in the air with fast wing movements and scans the ground for prey. Additionally, it engages in low flight over fields or pursues insects and birds in the air to hunt.
In terms of its status and conservation, the American kestrel is believed to be the most abundant falcon in North America. However, accurately determining its overall population is challenging due to the fluctuating nature of local populations caused by resource availability. Data collected from the USGS Breeding Bird Survey (BBS) shows that the breeding population of North America is gradually decreasing over time, with certain regions like New England and coastal California experiencing more significant declines.
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