American Kestrel Nest: Characteristics, Location, & Use

The American Kestrel nest is rather simple. Breeding pairs establish them within various structures, provided they offer a suitable enclosure and a small entrance hole. This article delves into the intricate details of the American Kestrel’s nest, exploring its physical characteristics, the selection of nest sites, and the flexibility it demonstrates in adapting to diverse nesting environments.

Typical American Kestrel nest, a shallow depression in a cavity. This is a nesting box where the owner has put gravel instead of wood shaving. Photo: Bird Cams, Cornell Lab of Ornithology.

Physical Characteristics of the American Kestrel Nest

The nest of an American Kestrel is a simple depression at the bottom of the nesting cavity. The depression is located in the center if it is a small cavity or on the side if cavity has ample room. The depression has a circular shape and keeps the eggs from rolling away.

American Kestrels are secondary cavity nesters, meaning they use existing natural cavities or those made by woodpeckers. Kestrels also frequently use nest boxes. 

The bottom of the nesting cavity

The bottom of the nesting cavity is important. If the bottom of the cavity is not flat or nearly flat with a surface where eggs can be laid and incubated, it becomes unsuitable as a nesting cavity for kestrels. In cavity where the bottom is flat but does not have dirt, debris or a soft substrate, where it is not possible to scrape a depression, eggs are laid on the bare bottom. 

Woodpecker cavities have a round bottom where eggs are kept in the middle even without any debris. Cavities without debris in the bottom (such as Nesting boxes without wood shavings), may trap eggs in the corners where they are not incubated properly. This often leads to poor hatching rate due to egg chilling.

Shape and size 

The shape and size of natural cavities used by the American Kestrel as nests are variable. Imagine an enclosure created by a broken limb or a hollow rotten trunk.

The size of the entrance appears to be more important. It has to be small enough to let an adult enter and exit the cavity comfortably. Cavities with large entrance holes are usually rejected.  

The depth of a nesting cavity can vary from 0.6 to 2.5 ft.

While any cavity can serve as nesting habitat for the American Kestrel, they consistently prefer abandoned cavities excavated by Pileated Woodpeckers: Photo: John Lynch.

Nesting Habitat

American Kestrels prefer open habitats with low-ground vegetation such as meadows, agricultural fields, prairies, deserts, open parklands, and edges of woodland. Ornithologist T.G Bolgooyen found that the American Kestrel prefers cavities surrounded by large (>20 ha) open patches covered with short ground vegetation with adequate hunting perches nearby. Kestrels are a strictly cavity nester and can use:

  • Natural nesting sites include natural cavities in trees and abandoned woodpecker-excavated cavities.
  • Man-made structures such as abandoned buildings, barns, a variety of sites in semi-urban areas, and nesting boxes offered to them.

Nesting boxes for American Kestrels 

Nesting boxes should be placed on poles or trees, at a height of 10-30 feet above the ground. The boxes should be made of wood, with a 3-inch diameter entrance hole. The interior should be filled with wood shavings or sawdust, and the floor should have drainage holes to prevent moisture buildup.

Summary Table: American Kestrel Nest Shape and Dimensions. Measurements of cavities excavated by Pileated Woodpeckers are given as reference as kestrels appear to regard them as their first choice for nesting.

Nesting CavityCharacteristics
Shape Any shape with an enclosure. The shape and area
of the chamber inside depends on the type of
cavity chosen to nest.
Round or teardrop (Shape of the Pileated
Woodpecker cavity)
Entrance hole∼4.7” high ∼2.5” wide (Pileated Woodpecker)

Entrances of approximately 3” diameter
allow easy access and exit to an adult
Kestrels. Cavities with large entrance
holes are rejected.
Depth of CavityVary from 0.5 to 2.4 ft
Height from the groundAmerican Kestrels nested in natural
cavities 6.5 to 80.3 ft from the ground
Nesting box presented by the Willistown Conservation Trust. Notice the perfect location to attach the nest box. Kestrels using this box will have an open area with low vegetation and plenty of perches to forage for food.

Territorial defense of the nest site

During the nesting season, American Kestrels are very territorial and will defend the nesting site against any intruders. In natural conditions pairs establish nesting territories far enough away from each other to avoid territorial conflicts.

When it comes to erecting nesting boxes, it is important to place each box at a safe distance to avoid conflicts. It is also important to avoid disturbing the nesting site during the nesting season, as this can cause stress to the nesting pair, which may result in nest abandonment. 

Nesting Habits

As an avid bird enthusiast, I have spent a lot of time observing American Kestrels. Here is what I have learned about their nesting behaviors.

Nest Site Selection

American Kestrels are flexible when it comes to nest selection. All they need is an enclosed site with soft substrate at the bottom where to scrape a small depression to lay the eggs. The nest location varies, but it is usually found in dead trees, snags, dirt banks, cliffs, barns, buildings, palm trees, and even below the top of old magpie nests.  

The selection of a suitable nest site is a critical decision for American Kestrels, and the male actively participates in this process. He finds potential nest sites and leads the female to them for an inspection and potential approval. 

Field studies have found that American Kestrels carefully consider various factors when selecting a nest site, ensuring the safety and well-being of their offspring.

1. Nest Location

Nest location is important for American Kestrels, as it provides a vital defense against avian and terrestrial predators. They prefer nest cavities that are isolated and away from branches that are close or touch the snag or tree to limit the access of predators to the nest site. Cavities with small openings, sturdy structures provide a secure environment for nestlings. 

2. Proximity to Food Sources: 

American Kestrels are active hunters, relying on a steady supply of prey to feed their young. Therefore, proximity to abundant food sources is a crucial consideration when selecting a nest site. 

Open fields, meadows, and grasslands, where their primary prey, small rodents and insects, are plentiful, are highly preferred nesting habitats. The ability to forage efficiently near the nest ensures a steady supply of food for the developing nestlings.

3. Field ornithologists studying nesting kestrels observed that nesting pairs avoid natural cavities and nesting boxes where the entrance hole faces the west.

Nest Construction

As mentioned above, the American Kestrel does not construct a nest. Instead, it relies on existing cavities or nest boxes. The only nest construction the female does is scraping a depression at the bottom of the cavity. This depression has no nesting material except for debris and regurgitated pellets. The nesting pair can gather pieces of wood, regurgitated pellets and similar materials around the nest, but if this material is not present just around the nest, the nest is just a depression on the bottom of the cavity.

Does the American Kestrel reuse the same nest?

Yes, the American Kestrel will reuse the same nest if it is available. They may use it for one breeding season and move on to another cavity the next. They can also return to the same cavity for two consecutive years and then move to another the third year.

The parasite load on a nest may be a reason why kestrels switch to another natural cavity. Kestrels using nest boxes that were cleaned up every year after the breeding season, therefore parasites were not a problem, had kestrels returning for multiple consecutive breeding seasons.  

Does the American Kestrel also use their nesting cavities as roosting sites?

Yes, the American Kestrel will use their nesting cavities as roosting sites outside of the breeding season. American Kestrels are solitary birds except for the breeding season when they associate with a breeding partner.

The Lesser Kestrel (Falcon naumanni), a close relative that occurs in Africa and Eurasia is a gregarious bird often traveling and roosting together.  

Does the American Kestrel experience a shortage of nesting sites?

Research on the American Kestrel found that they do experience a shortage of nesting sites. This is because they are secondary cavity nesters and do not excavate their own cavities. Instead, they rely on natural cavities or holes made by woodpeckers.

Due to the loss of natural habitats and the decrease in the number of woodpeckers, the American Kestrel is facing a shortage of nesting sites. This problem is exacerbated by competition for cavities with Wood Ducks, Great Crested Flycatcher, Bluebirds, Eastern Screech Owls and introduced species such as the European Starling.

The shortage of suitable nesting sites has led to a decline in their population, as they are unable to reproduce and raise their young.

What is being done to help

To address this issue, many conservationists and wildlife organizations have started installing nest boxes for the American Kestrel. These boxes mimic natural cavities and provide a safe and secure place for the birds to nest and raise their young.

Kestrels readily  take the nesting boxes. So much so that in many places they prefer breeding in nesting boxes than in natural and woodpecker-excavated cavities.

Providing these nest boxes results in less nest predation and higher reproductive success, which in turn helps increase the kestrel population.

Predators of American Kestrel Nests

As a cavity nester, the American kestrel is vulnerable to predators that can easily access their nests. The most common predators of Kestrel nests include snakes and  raccoons.

Snakes can easily climb trees and enter the nest cavities. Raccoons on the other hand, are known to raid bird nests for eggs and young chicks. Racoons are especially active during the breeding season when kestrels are most vulnerable.

What do Kestrels do to protect their nests?

To protect their nests from predators, American Kestrels nest in cavities that are high off the ground. This makes it more difficult for predators to access the nests. Additionally, kestrels will often use abandoned nests of other birds, which are less likely to be detected by predators.

Despite these adaptations, American Kestrels still face a number of threats from predators. As such, it is important for conservationists to monitor kestrel populations and take steps to protect their nests from predators.

The American Kestrel is flexible about the type of cavities it uses. This pair has chosen an old and rusty power structure to raise a family.

American Kestrel nests in urban areas

The American Kestrel is an adaptable bird that has found a surprising abundance of nesting opportunities in urban environments. 

Kestrels have repurposed human-made structures, using them into nesting sites for raising their young. Abandoned buildings, bridges, palm trees, and even ornamental bird houses have been used as nesting sites

These urban nesting sites offer several advantages for American Kestrels. 

  • Elevated structures, such as bridges and rooftops, provide excellent vantage points for scanning their surroundings, allowing them to spot potential prey with ease. 
  • The abundance of lights in urban areas attracts insects, which form a significant part of the kestrel’s diet. 
  • Fewer predators such as snakes and raccoons are found in urban areas. These predators are mostly unable to reach the cavities used by kestrels in urban environments resulting in a greater reproduction rate.

American Kestrels’ Adaptations to the lack of nesting sites

As natural areas have been transformed into agricultural fields, urban landscapes, and suburban developments, suitable nesting sites for these birds have dwindled. 

Unlike some other bird species that are specific in their nesting requirements, American Kestrels are opportunistic nesters. They readily accept a variety of natural cavities. This flexibility has allowed them to persist in a variety of habitats, even those that have undergone significant modification.

American Kestrels have shown a remarkable willingness to accept artificial nest boxes. These boxes, strategically placed in suitable habitats, provide valuable nesting opportunities for kestrels, particularly in areas where natural cavities are scarce. The use of nest boxes has been instrumental in maintaining and even expanding kestrel populations in many regions.

Beyond Accepting Nesting Boxes

The American Kestrel’s adaptability extends beyond nest site selection. These birds have also shown a remarkable ability to adjust their hunting strategies to different habitats. 

In urban areas, where open fields and meadows may be limited, they have learned to hunt along roadsides, parks, and even rooftops. Their adaptable foraging behavior has allowed them to find sufficient food sources in these altered environments.

Conservation Efforts

As a species of concern, the American Kestrel has been the focus of several conservation efforts. One of the most successful conservation measures has been the establishment of nest boxes. These boxes mimic natural nesting cavities and provide safe and secure nesting sites for the birds.

In addition, several organizations have launched campaigns to raise awareness about the plight of the American Kestrel and to promote conservation efforts.

Another important conservation effort is the monitoring of kestrel populations. This involves tracking the number of kestrels in a given area, as well as their breeding success and survival rates. This information is used to identify areas of concern and to develop conservation strategies to address these issues.

Finally, habitat conservation is a critical component of American Kestrel conservation. This involves protecting and restoring the open habitats, such as grasslands and meadows, that the birds rely on for hunting.


  • 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.