The American Kestrel (Falco sparverius) is the smallest and most common falcon species in North America. Roughly the size of a mourning dove, this brightly colored, highly predatory member of the Falconidae family combines the speed and precision of a raptor with the agility of a songbird. Found coast-to-coast in open habitats across the United States, the American Kestrel is easily recognized by its unique hunting method: hovering stationary in mid-air over fields before diving on its prey.
American Kestrel Quick Facts
| Common Name | American Kestrel, Sparrow Hawk |
| Scientific Name | Falco sparverius |
| Size & Length | 8.7 to 12.2 inches |
| Wingspan | 20.1 to 24.0 inches |
| Weight | 2.8 to 5.8 ounces |
| US Range | Nationwide year-round; northernmost populations migrate south |
| Migration | Partially migratory (Depends on winter latitude) |
| Conservation Status | Declining locally; strictly monitored |
How to Identify American Kestrels
American Kestrels possess a slender, aerodynamic build with long, narrow, pointed wings and a long, square-tipped tail.
Distinct Head Markings (Both Sexes)
Regardless of sex, all American Kestrels share a striking, high-contrast face pattern. They feature a white face accented by two vertical, bold black stripes on each cheek, known as “malar stripes” or mustaches. Additionally, the back of their head features two hidden black spots called ocelli, which mimic eyes. These false eyes confuse potential predators approaching from behind and deter songbirds from mobbing the kestrel.
Male vs. Female Plumage
American Kestrels are highly sexually dimorphic, making field identification straightforward.
- Adult Males: Exceptionally colorful. They feature slate-blue wings that contrast with a warm, rufous-cinnamon back. Their tail is bright rufous with a single, thick black subterminal band and a white tip. The breast is pale buff with delicate black spotting.
- Adult Females: Noticeably larger than males but less colorful. Their wings, back, and tail are a uniform, warm reddish-brown heavily barred with dark brown horizontal bands. Their breast is creamy white with dense, vertical brown streaks rather than spots.
Habitat and U.S. Range
American Kestrels occupy a massive geographical range encompassing the entire contiguous United States and Alaska. While southern and coastal populations are permanent, year-round residents, kestrel populations that breed in Canada and the northernmost US states migrate south to the southern tier of the country each autumn.
Kestrels are birds of wide-open spaces and require flat terrain with minimal canopy cover:
- Agricultural fields, pastures, and orchards.
- Overgrown meadows, prairies, and sagebrush deserts.
- Suburban parks, highway corridors, and vacant industrial lots.
They require elevated perches—such as telephone wires, fence posts, and lone trees—to scan the ground for food. They completely avoid dense, unbroken woodlands.
Diet and Advanced Hunting Mechanics
Despite their classification as falcons, American Kestrels do not typically hunt other birds in high-speed aerial pursuits like the Peregrine Falcon. Instead, they operate as sit-and-wait predators or aerial hoverers, focusing their efforts on the ground.
Seasonal Diet Shifts
Their diet changes dynamically depending on seasonal abundance:
- Summer: Large insects form the bulk of their food. They consume massive quantities of grasshoppers, crickets, beetles, cicadas, and dragonflies.
- Winter: As insects die off, they switch to vertebrate prey, including meadow voles, deer mice, shrews, small snakes, lizards, and occasionally small songbirds like House Sparrows.
Ultraviolet Vision and Hover-Hunting
When hunting in open terrain, kestrels frequently engage in “wind-hovering.” They face directly into the wind, flapping their wings rapidly while adjusting their tail to hold their head completely motionless in mid-air.
From this vantage point, kestrels utilize a remarkable biological adaptation: the ability to see ultraviolet light. Because small rodents like voles continuously mark their runways with urine and feces—which reflect ultraviolet light—the kestrel can see brilliant, glowing navigation trails across fields. This allows them to zero in on the exact locations of active rodent populations with pinpoint accuracy.
Conservation and the Nest Box Solution
While the American Kestrel remains widespread, long-term data from Breeding Bird Surveys indicate a steady, concerning population decline across much of their traditional US range. The primary drivers are habitat loss due to suburban sprawl, the removal of dead trees containing nesting holes, and heavy pesticide use that eliminates their insect food supply.
Because kestrels are secondary cavity nesters, they cannot excavate their own holes. They rely entirely on old woodpecker cavities or natural hollows in dead trees to lay eggs. You can actively support kestrel conservation by installing a targeted nesting box.
1. Build or Buy to Correct Specs
A kestrel box must follow precise structural dimensions to ensure safety and prevent predation:
- Floor Size: 8 x 8 inches.
- Box Depth: 12 to 15 inches.
- Entrance Hole: Exactly 3 inches in diameter, positioned near the top of the box. A hole larger than 3 inches allows larger predators like raccoons or Great Horned Owls to enter.
2. Strategic Placement
- Height: Mount the box 10 to 20 feet off the ground on a sturdy wooden pole, the side of an isolated barn, or a lone tree.
- Habitat: Face the box toward wide-open grassland or agricultural fields. The entrance should ideally face east or south to avoid prevailing storm winds.
- Bedding: Add a 2-inch layer of clean wood shavings (not sawdust) to the bottom of the box, as kestrels do not bring in their own nesting materials.
3. Manage Pest Competitors
Because European Starlings (Sturnus vulgaris) are invasive cavity-nesters, they will aggressively try to colonize kestrel boxes. Check the box regularly in early spring and remove starling nests immediately to keep the cavity open for native kestrels.
Vocalizations and Communication
American Kestrels are highly vocal, especially when defending their breeding territory or communicating between pairs. Their most famous call is a loud, rapid, high-pitched scolding cry that sounds like “klee-klee-klee-klee” or “killy-killy-killy.” They launch this call while diving at intruders or when flushed from utility lines.