American Kestrel

(Falco sparverius)

April 1999 Fish and Wildlife Habitat Management Leaflet Number 3

General Information

The American kestrel is one of the most common and colorful

birds of prey in North America. Because of its small size and

colorful plumage, it can easily be mistaken for a songbird as it

sits atop a utility pole or wire. However, once witnessed

hovering over an open field in search of prey, the kestrel’s

predatory nature becomes apparent. A member of the falcon

family, the American kestrel is closely related to the peregrine

falcon and merlin. The bird is often referred to as the sparrow

hawk because of its small size. Its scientific name, Falco

sparverius, holds the Latin meaning, "falcon of the sparrows."

Although its scientific name and the commonly used name

"sparrow hawk" imply that the kestrel feeds exclusively on

small birds, the majority of the kestrel's diet consists of insects

and small mammals. As is the case with many beneficial

predator species, the kestrel’s value lies in the role it plays in

keeping insect and small rodent populations in check.

In the early and mid-1900s, American kestrel populations declined in many parts of North America as

a result of the loss of nesting habitat in the form of tree and other natural cavities. A growing human

population contributed to the loss of nesting habitat as fencerows and tree-lined field borders were

removed to provide crop fields and make way for expanding urbanization. In recent years, the removal

of dead standing trees, or snags, for firewood, and the continued clearing of fencerows and hedgerows

has had a significant impact on the success of the American kestrel. A management practice that has

helped to improve the kestrel’s status is the placement of artificial nesting structures on road signs

along highways and other areas of suitable kestrel habitat. Due in part to the provision of artificial

nesting structures throughout North America, the American kestrel is once again a commonly seen bird

of prey. The ongoing recovery of the American kestrel is an example of how sound wildlife

management practices have been used to increase the survival success of an individual wildlife species.

This pamphlet is designed to serve as an introduction to the habitat requirements of the American

kestrel and to assist land managers in the development of a comprehensive kestrel management plan.

The success of any individual species management plan depends on targeting the specific needs of the

desired species and analyzing the designated habitat area as a whole to ensure that all required habitat

elements are present. This guide also provides monitoring guidelines to document success and to

ensure that problems are addressed as they arise.

Wildlife Habitat Management Institute
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Range

The range of the American kestrel spans across

nearly all of North America. Kestrels breed as

far north as central and western Alaska, across

northern Canada to Nova Scotia, and extend

south throughout North America into central

Mexico, Baja, and the Caribbean. Kestrels are

local breeders in Central America and are

widely distributed throughout South America

as well. Most of the birds breeding in Canada

and the northern United States migrate to the

southern United States and Mexico in the winter. The summer range of the kestrel is very similar to

the bird’s breeding range. Kestrels that summer in warmer regions remain as year-round residents.

Habitat Requirements

General

American kestrel habitat consists of open fields containing widely scattered trees, pastures adjacent to

woodland borders, deserts, as well as rural, urban, and suburban settings consisting of buildings and

other structures providing perching and nesting sites. Common foraging habitats used by kestrels

include open grassy meadows and highway and power line rights-of-way. Foraging habitat is

supplemented by nearby trees that can serve as perching or nesting sites. Perches in the forms of

isolated trees and utility poles and wires are essential habitat components for the kestrel’s hunting

activities. Often, the lack of hunting perches is a limiting factor in local kestrel populations. Although

American kestrel populations are on the rise, the largest threat to their future is the continued loss of

nesting habitat. By protecting snags, and properly managing open areas, landowners can assist in the

continued success of kestrels and other species that rely on similar habitat.

Food

The American kestrel’s primary summer food consists of insects such as grasshoppers and crickets.

Small mammals such as mice, rats, shrews, gophers, and young ground squirrels, and birds are

sometimes eaten in summer as well. The absence of an abundant winter supply of insects in the

northern reaches of the bird’s winter range forces the kestrel to feed primarily on small mammals in

the winter months. Other food items that are occasionally consumed by kestrels include frogs, small

snakes, bats, and lizards. Kestrels will use perches, such as a branch or power line, to scout hunting

areas. However, the bird typically feeds by gliding or hovering over an area before swooping to take

its prey either on the wing or on the ground.

Important American kestrel food items. The following species are known to be important food items in the diet of

American kestrels. Those species in bold print are of particular value for their usefulness as a winter food source.

Insects:

Grasshoppers, crickets, beetles, moths, and others

Small Mammals and Birds:

mice rats shrews gophers ground squirrels small birds frogs small snakes bats lizards
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Cover – Nesting

The American kestrel is

a cavity nesting species,

but does not create its

own nesting cavity. It

relies heavily on the

abandoned nesting

cavities of woodpeckers,

squirrels, and magpies.

Common nesting sites

include hollows in trees

and cacti, holes in cliffs,

crevices in barns, and

building roofs, walls, and ledges. Nesting boxes are also

readily accepted for nesting. Male kestrels typically will

select cavities 15 to 30 feet above the ground in areas

where abundant open space exists to provide an insect

base on which to forage. The role of the nesting cavity

remains important throughout nestling development, as

young remain in the nest dependent upon parent kestrels

for roughly 30 days before fledging. In areas where

natural snags comprise the most common nesting

habitat, optimal snag-to-acreage ratio is calculated for

one acre of land. It is advised that on one acre of

forested land, there should be one snag larger than 20

inches dbh (diameter at breast-height), four snags

between 10 and 20 inches dbh, and two snags between 6 and 10 inches dbh. In areas managed for

kestrels where snags or natural cavities are scarce, nest boxes can be placed to augment the availability

of natural cavities.

Cover – Winter

In areas where kestrels winter, habitat requirements

differ very little from common nesting or summer

cover types. Woodland edges, highway and power

line rights-of-way, pastures, and farmlands where

adequate ratios of snags exist with open grassy areas,

provide adequate winter cover needs. In the bird’s

western range, cavities in cacti and holes in rock

cliffs provide adequate roosting habitat. Nest boxes

may provide some individuals with winter roosting

sites as well. Due to the varying temperatures

between the cooler, northern reaches and warmer,

southern reaches of the kestrel’s range, availability

of common food sources may differ, but habitat

requirements remain constant. Year-round

availability of insects plays a key role in determining

where kestrels winter.

Nest Box Design. -- Nest boxes should be

constructed of a weather-resistant wood such as

cedar. The wood can be painted or stained but

only on the outside surface. The entrance hole

should be 3 inches in diameter. Numerous nest

box designs have been used with success; Fig. 1

provides one example. A good method of

assisting fledglings in their climb from the nest to

the entrance hole is to roughen up the inside

wood surface under the hole with a chisel. It is

recommended that the outside surface below the

entrance hole be roughened as well. The bottom

of the box should be lined with 2 to 3 inches of

wood chips or shavings, straw, or pine straw.

The lid or one side of the box should be

removable or on a hinge to facilitate monitoring

and cleaning. Three or four _-inch drain holes

should be drilled into the box bottom. Recessing

the box floor _-inch into the bottom edge of the

walls will help protect the floor from weather rot.

Ventilation and shade requirements are met by

overhanging roofs and construction designs

described in Fig. 1. All kestrel boxes affixed to

poles should be fitted with a galvanized sheet

metal predator guard (see Fig. 2). The predator

guard should be placed on the pole 6 to 12 inches

below the bottom of the box. Also, to help deter

predation, an even coating of non-drying

crankcase grease or carnauba wax can be applied

to the pole from the ground to six inches below

the box.
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Water

Water requirements for the American kestrel are assumed to be met when the bird inhabits areas

containing suitable nesting and wintering habitat. The kestrel’s foraging behavior and the types of

food eaten provide it with an adequate amount of water.

Interspersion of Habitat Components

In order for successful kestrel reproduction and survival to occur, all required habitat components must

be available in relative proximity to one another. Because some kestrels migrate, and most are highly

mobile during winter, the most critical aspect of habitat interspersion, or the mix of different habitat

types, is the proximity of suitable foraging habitat to spring nesting habitat. The highest-quality

nesting habitat is of little use if the nearest open foraging habitat is not within close proximity.

Likewise, the best foraging habitat will not support nesting pairs if there are no available nest cavities.

Ideal interspersion of American kestrel habitat components consists of a complex of open grassy fields,

pastures, highway and power line rights-of-way, woodland edges, perches in the form of trees, shrubs,

utility wires or telephone poles, and numerous natural or artificial nesting cavities throughout.

Minimum Habitat Area

Minimum habitat requirements become an issue only when two or more nesting pairs desire to nest

within one general area. Because kestrels are active territorial hunters, nesting pairs often prefer to

nest in cavities that are either separated by some distance or by a natural geographic feature, such as a

large hill or wide valley. Pairs may nest in close proximity to one another when space and territoriality

requirements are met. Nest boxes should be placed at least one-half mile apart and in locations

surrounded by at least one acre of open space. Lands outside the immediate planning area should be

considered when making the determination of minimum habitat area for kestrel reproduction.

Nest Box Placement. -- Kestrel nest boxes should be placed on a tree, post, or the side or a barn or outbuilding

with the entrance hole 15 to 20 feet above the ground. Boxes placed on posts should be equipped with a predator guard

as shown in Fig. 2. The box entrance should face southeast to avoid direct winds and to take advantage of the sun's

rays. Open fields, pastures, hedgerows, and highway and power line rights-of-way comprised of or surrounded by at

least one acre of space within 20 yards of a tree with dead limbs, a utility pole, or other perch make up the best habitat

in which to place nest boxes. These habitat types in close proximity to creeks and wet areas have proven to be very

productive for kestrels as well. Place boxes well away from buildings and other human habitations that may harbor

starling populations. Also, placing boxes more than 50 yards from woodland edges will help reduce competition for

boxes with squirrels. Open areas will provide food for hunting and adjacent trees, utility poles, and fence posts are used

as plucking perches by the male kestrel to dismember prey before the female feeds it to the young. Perches are also

used for preening, courting, and by fledglings when learning to fly. Individual nesting pairs require an adequate

territory in which to nest and forage. Therefore, nest boxes should be placed at least one-half mile from one another.

Boxes placed near or along roadsides should be placed with the entrance hole facing away from the road.

In agricultural areas, it is important that nest boxes be located a distance away from fields that are heavily treated with

pesticides since the birds feed primarily on insects. Overall, one should attempt to accommodate the bird’s natural

nesting instincts and requirements while still allowing for routine monitoring during the nesting season. If predators

such as raccoons or snakes discover an occupied nest box, they likely will continue to return for eggs or nestlings in the

future. If such predation becomes a problem, relocating troubled nest boxes after a few seasons may be beneficial.
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Fig. 1. American kestrel nesting box design.
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Fig. 2. Standard cone-shaped predator guard.
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American Kestrel Habitat Requirements Summary Table.

Habitat Component Habitat Requirements

Food – Young • Insects - primarily grasshoppers.

Food – Adult • Insects - primarily grasshoppers and crickets.

• Mammals, birds, reptiles, and amphibians (mice, rats, shrews, gophers, ground squirrels,

sparrow-size birds, frogs, small snakes, bats, lizards).

Nesting Cover • Natural tree cavities or nesting boxes in open fields, along woodland edges, pastures,

hedgerows, and highway and power line rights-of-way within 20 yards of a tree with dead

limbs, a utility pole, or other perch. Cavities in cacti, cliffs, crevices in barns, and

building roofs, walls, and ledges.

Brood-Rearing

Cover

• Same requirements as nesting cover. Nestlings remain in the nest dependent upon parent

kestrels for roughly 30 days before fledging.

Winter Cover • Woodland edges, highway and power line rights-of-way, pastures, and farmlands where

adequate ratios of snags exist with open grassy areas that support small-mammal

populations. Cavities in cacti and holes in rock cliffs.

Water • Water requirements for kestrels are met through daily food intake.

Interspersion • Prefer a complex of open grassy fields, pastures, and highway and power line rights-ofway, either mown or of low growth, woodland edges, widely scattered trees, snags, and

perches in the form of trees, shrubs, utility wires or telephone poles.

Minimum Habitat

Size

• Adequate distance to allow for territoriality or the presence of a natural geographic

feature, such as a large hill or wide valley, that allows for two or more nesting pairs in an

area. Likewise, nest boxes should be placed a distance of at least one-half mile apart in

locations surrounded by at least one acre of open space.

Limiting Factors

For planning purposes, use the inventory table of limiting factors on the next page to inventory the site

to determine the availability of each of the basic habitat components, based on the above narrative

habitat requirement descriptions. Habitat components that are absent or rated low are limiting habitat

quality for American kestrels.

Exotic Species Control – Exotic species, specifically the European starling, compete with American kestrels for nesting

cavities. Simple steps can be taken, however, to reduce nest box use by starlings. If starlings are found to be nesting in a box,

remove and dispose of the nest and its contents. The actual trapping and elimination of the adult bird in the box is more effective

than simply removing the nest. Trapping with inside-the-box traps or bait-type traps such as those made by Trio and Hav-a-hart

is recommended. If relocation of trapped birds is preferred over disposal, the birds should be taken a distance of at least three

miles from the trapping area and released in similar habitat. However, the significant drawback of this management technique is

that it simply may move the problem birds from one location to another. If you are uncomfortable with removing the birds or

nests, another option is to vigorously shake the eggs, or addle them, for 60 seconds and leave them in the nest so that the female

will continue to expend reproductive energy without hatching success. This also prevents the starling from attempting to take over

another nest box. Other native cavity-nesting birds, such as eastern screech owls and eastern bluebirds may use and are welcomed

in nest boxes. Because they are federally protected, it is illegal to destroy them, their nests, or their eggs. Therefore, nest monitors

must be certain of the bird species nesting in a box before control measures are implemented. Two aids, Guide to Nests, Eggs, and

Nestlings of North American Birds, and Birds’ Nests (in the Peterson Field Guide Series) are recommended (complete citations

included in the reference section). Note: Box placement is the best means of controlling exotic species. Careful box placement

will also reduce competition from squirrels. Placing boxes a good distance from buildings and human habitation and orienting

them with a southern exposure will help prevent starlings from using kestrel boxes. Placing boxes in open grassy areas away from

woodland edges will help to reduce over-use of boxes by non-target native bird species and squirrels.
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Inventory of Limiting Factors

Availability/Quality

Habitat Component High Medium Low Absent

Food

Nesting cover

Brood-rearing cover

Winter cover (may not be applicable if kestrels do

not winter in the area)

Interspersion of habitat components

Minimum habitat size

Management Prescriptions

Management treatments should address the habitat components that are determined to be limiting

American kestrel habitat potential. For planning purposes, select among the possible action items

listed below to raise the quality or availability of each habitat component determined to be limiting. A

list of programs that may provide financial or technical assistance to carry out specific management

practices is given, when applicable.

Habitat

Component

Management options for increasing

habitat quality or availability

Assistance

Programs

• Maintain grassy and open field areas by conducting rotational mowing

and managed grazing where appropriate.

Food WHIP, EQIP, PFW, CRP

• Preserve snags and widely scattered trees and other perches in close

proximity to open field areas.

N/A

• Install nesting boxes in open field areas. WHIP, PFW

• Preserve large live and dead-standing hardwood and softwood trees

conducive to natural cavities in and adjacent to open field areas.

N/A

Nesting and

brood-rearing

Cover

• Preserve snags, building structures, and cacti conducive to nesting

cavities.

N/A

• Preserve snags and widely scattered trees and other perches in close

proximity to open field areas.

N/A

• Preserve large live and dead-standing hardwood and softwood trees

conducive to natural cavities in and adjacent to open field areas.

N/A

• Preserve snags, building structures, and cacti conducive to nesting

cavities.

N/A

Winter cover

• Leave nesting boxes in open field areas year-round. WHIP, PFW

Interspersion

& minimum

habitat size

• Combine above prescriptions to increase interspersion of habitat

components or amount of suitable kestrel habitat.

WHIP, CRP, PFW, EQIP

Landowners interested in making their individual efforts more valuable to the community can work

with WHC and NRCS to involve school and scout groups and their families in habitat projects. A

kestrel management project is an easy way to provide fun, hands-on learning opportunities, especially

for children. If the land is corporate owned, encourage interested employees to become involved.

Involve students or scouts in building and monitoring nest boxes. The educational benefits can greatly

increase the value of your individual kestrel management project.
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Programs that provide technical and financial assistance to develop fish and wildlife habitat on

private lands.

Program Land Eligibility Type of Assistance Contact

Conservation Reserve

Program (CRP)

Highly erodible land,

wetland, and certain

other lands with

cropping history.

Stream-side areas in

pasture land

50% cost-share for establishing permanent cover and

conservation practices, and annual rental payments

for land enrolled in 10 to 15-year contracts.

Additional financial incentives are available for

some practices

NRCS or FSA State or

County Office

Environmental Quality

Incentives Program

(EQIP)

Cropland, range,

grazing land & other

agricultural land in

need of treatment

Up to 75% cost-share for conservation practices in

accordance with 5 to 10-year contracts. Incentive

payments for certain management practices

NRCS State or County

Office

Partners for Fish and

Wildlife Program

(PFW)

Most degraded fish

and/or wildlife

habitat

Up to 100% financial and technical assistance to

restore wildlife habitat under minimum 10-year

cooperative agreements

Local office of the U.S.

Fish and Wildlife

Service

Waterways for Wildlife Private land Technical and program development assistance to

coalesce habitat efforts of corporations and private

landowners to meet common watershed level goals

Wildlife Habitat

Council (301-588-

8994)

Wildlife at Work Corporate land Technical assistance on developing habitat projects

into a program that will allow companies to involve

employees and the community

Wildlife Habitat

Council (301-588-

8994)

Wildlife Habitat

Incentives Program

(WHIP)

High-priority fish and

wildlife habitats

Up to 75% cost-share for conservation practices

under 5 to 10-year contracts

NRCS State or County

Office

State fish and wildlife agencies and private groups such as state Audubon societies, American Birding

Association, Hawk Mountain Sanctuary, and others may have assistance programs or other useful tools

in your state.

State or local contacts

Nest Box Monitoring. -- Before nesting boxes are erected, a maintenance, monitoring, and data collection plan should be

developed to maximize program success. Unmonitored boxes may be counter-productive by helping to increase populations of

exotic competitor species such as European starling. It is essential to erect only as many boxes as can be properly monitored. To

avoid discouraging nesting kestrels, boxes should not be visited more often than four or five times each year. Because the kestrel

has such an expansive range throughout North America, the time period in which nesting activity begins in various regions differs.

In southern, western, and other warm regions in which the kestrel is a year-round resident, eggs are typically laid by the first week

of March. Colder, more northern reaches typically see eggs laid in mid to late April. The establishment of nesting territories

generally begins three to four weeks prior to egg laying; therefore, the first visit to nest boxes should occur before this date. First

visits should clear nest boxes completely of all materials, as well as make any necessary repairs to boxes. Two inches of wood

chips or shavings should be placed in boxes at this time. Observation of nest boxes from a distance of 50 to 75 yards is necessary

to determine if nesting activity is taking place. Observations should be made between mid-morning and late afternoon for 15 to 30

minutes, three to four times a week, from mid-March through late June depending on the region. Activity common to nesting

kestrels consists of frequent entering and exiting of nest boxes by both the male and female bird. Second visits to nest boxes

should occur 10 to 14 days after the male kestrel is seen bringing food into the nest box. Opening boxes before this time may

prevent the female from laying her entire clutch of eggs or discourage her from using the box. Second visits should document the

eggs, being careful not to unnecessarily disturb the nest. Third visits should be made about two weeks prior to the expected

fledging date of the nestlings. Approximate fledging dates can be determined by adding 46-50 days to the estimated date that the

last egg was laid. A count of nestlings in the box should be recorded. Monitors should use extreme caution when opening boxes

at this time to prevent nestlings from prematurely exiting the box. Banding of nestlings should occur during the third visit if part

of the nest box program. Banding activities should be done in cooperation with a bird expert and licensed bander. The fourth

visit should occur one month after the nestlings have fledged to clean nest boxes of all nesting materials. Boxes should remain out

during the winter to provide winter cover for kestrels, screech owls, and other resident birds. European starling nests should be

removed and disposed of when found to be the sole contents of a box and no sign of kestrel use is apparent. Wildlife Habitat

Council member organizations can enroll their monitoring program in WHC’s Nest Monitoring Program, useful in WHC’s

Corporate Wildlife Habitat Certification Program. Enrollment can be accomplished by contacting the WHC Nest Monitoring

Program Coordinator at (301) 588-8994.
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Nest Box Data Sheet

Landowner, Company, or Site Name__________________________________________

Location____________________________

Year________________ Monitor_____________________________

Box Number_________

First Brood Second Brood

Species

Eggs Laid

Young Hatched

Young Fledged

Hatch Date

Cause of Nest Failure

Notes/Observations:

Date___________________

Year________________ Monitor_____________________________

Box Number_________

First Brood Second Brood

Species

Eggs Laid

Young Hatched

Young Fledged

Hatch Date

Cause of Nest Failure

Notes/Observations:

Date___________________
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References

Baicich, P. and C. Harrison. 1997. Guide to Nests, Eggs, and Nestlings of North American Birds.

Academic Press and Harcourt Brace. 347 pp.

Bookout, T.A., Editor. 1994. Research and Management Techniques for Wildlife and Habitats. Fifth

ed. The Wildlife Society, Bethesda, MD. 740 pp.

Brewer, R., G. McPeek, R. J. Adams, Jr. 1991. Breeding Birds of Michigan. Michigan State

University Press. East Lansing, Michigan. 570 pp.

Chambers, R. 1983. Integrating Timber and Wildlife Management. State University of New York

College of Environmental Science and Forestry. Syracuse, New York. 150 pp.

Ehrlich, P. R., D. Dobkin, and D. Wheye. 1988. The Birder's Handbook. Simon and Schuster, Inc.,

New York, New York. 780 pp.

Heintszelman, D.S. 1964. Spring and summer sparrow hawk food habits. Wilson Bulletin. 76:323-

330.

Henderson, C.L. 1987. photograph. Landscaping for Wildlife. Minnesota Department of Natural

Resources.

Henderson, C. L. 1992. Woodworking for Wildlife. Minnesota Department of Natural Resources. St.

Paul, Minnesota. 112 pp.

Peterson, R. T. 1980. Eastern Birds. Houghton Mifflin Press, Boston, Mass. 377 pp.

Rudolph, S.G. 1982. Foraging strategies of American kestrels during breeding. Ecology. 63:1268-

1276.

Sauer, J. R., J. E. Hines, G. Gough, I. Thomas, and B. G. Peterjohn. 1997. The North American

Breeding Bird Survey Results and Analysis. Version 96.4. Patuxent Wildlife Research Center, Laurel,

MD.

Terres, J. K. 1991. The Audubon Society Encyclopedia of North American Birds. Wings Books,

New York. 1110 pp.
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NRCS

Wildlife Habitat Management Institute

100 Webster Circle, Suite 3

Madison, MS 39110

(601) 965-5886

In cooperation with partners, the

mission of the Wildlife Habitat

Management Institute is to develop

and disseminate scientifically based

technical materials that will assist

NRCS field staffs and others to

promote conservation stewardship of

fish and wildlife and deliver sound

habitat management principles and

practices to America’s land users.

Wildlife

Habitat Council

1010 Wayne Avenue, Suite 920

Silver Spring, MD 20910

(301) 588-8994

The Wildlife Habitat Council's

mission is to increase the amount

of quality wildlife habitat on

corporate, private, and public land.

WHC engages corporations, public

agencies, and private, non-profit

organizations on a voluntary basis

as one team for the recovery,

development, and preservation of

wildlife habitat worldwide.

The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, national origin, sex, religion, age,

disability, political beliefs, and marital or familial status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative

means for communication of program information (Braille, large print, audiotape, etc.) should contact the USDA Office of Communications at (202) 720-

2791.

To file a complaint, write the Secretary of Agriculture, U.S. Department of Agriculture, Washington, DC 20250, or call 1-800-245-6340 (voice) or (202) 720-

1127 (TDD). USDA is an equal employment opportunity employer.