Northern Prairie Wildlife Research Center
Establishing a Nest Box Program for American Kestrels Along an Interstate
Establishing Your Interstate Highway Nest Box Program for American Kestrels
The ideas presented here focus on providing kestrel nesting sites along interstate
highways; they are applicable to any highways with grassy rights-of-way and road
signs supported by steel posts.
The first step: Obtain permission from your local transportation authority
to establish and monitor a nest box route.
Erecting Nest Boxes and Working Along the Interstate:
- Building Nest Boxes
- These may be built from any of the designs available. The design shown on
pages four and seven provides enough board above and below the box for wrapping
the banding material to secure the box to the sign-post. The kestrel nest
box featured here is suitable for use in other locations, such as the outer
wall of a barn or a windmill. We recommend white pine (#2) for box construction.
Painting the boxes will increase their useful life. Using earth-tone paint
(avocado, tan, or gray) allows boxes to blend in with the environment.
- Safety Equipment
- Abide by the guidelines set forth by your transportation authority. Use
extreme caution while working along the interstate. It is advisable to have
a yellow caution light on top of your vehicle and to wear a blaze orange vest
and a hard hat.
- Placement of Nest Boxes
- Attach the box to the sign-post 10 to 30 feet above ground. Space the boxes,
on average, one mile from each other and no closer together than one-half
- Box use by kestrels will most likely be highest in open areas where natural
cavities are lacking. If a box has been in place for three or four years and
has not been used, it is advisable to choose a new site.
- If a wetland is adjacent to the highway, using somewhat larger Wood Duck
nest boxes will provide nesting opportunities for these birds as well as kestrels.
Kestrels will use the larger Wood Duck nest box, but kestrel nest boxes are
too small for Wood Ducks. Nest box plans for Wood Ducks are widely available.
(see Nest Structures for Ducks
- Attachment of Nest Boxes
- Metal banding material is used to secure the nest box to the steel sign-post.
Use "C"-clamps to hold the box in place while working. Bands are applied with
a tool that is normally used for strapping steel bands around freight. This
steel binder is expensive, but is available for rent at many of the outlets
that rent tools. One strap is wrapped around the sign-post and board extending
above the box, and a second strap is wrapped below in the same manner (see
photo). A third strap may be wrapped around the entire box and post and will
help hold the box in place in high winds. Stainless steel banding is more
expensive than galvanized steel but will not require replacement. In Iowa,
galvanized steel banding rusts and breaks in about six years.
- Checking and Maintaining Nest Boxes:
- Nest boxes should be visited at least three or four times each year. The
first visit should occur before the kestrels begin territory establishment.
The date of the first visit will, of course, vary from one region to another.
Because kestrels establish their territories in mid-March in Central Iowa,
in this area the first box check is made in late February or early March.
At this time, nest boxes are cleaned and repaired, and three to four inches
of wood chips, wood shavings, or straw are added to the bottom of each box.
- To monitor nest box use by kestrels, boxes should be visited two to three
times during the nesting season. Several additional visits will be necessary
to obtain accurate data to evaluate nesting success. To determine whether
the young kestrels have successfully left a nest box, one visit should occur
within five days of their expected nest departure. Because kestrels are especially
sensitive to disturbance during the first two weeks of their 30-day incubation
period, avoid visiting the boxes at this time (last two weeks of April in
Central Iowa). The last visit should be made in late summer after nesting
to remove old nesting material and to do repairs.
Young American Kestrels hunting socially after nest departure.
- European Starlings often nest in kestrel nest boxes. Starlings replace or
cover wood chips with grass and other material and lay five, six or seven
pale blue eggs. If starlings are found nesting, remove the nest and replace
it with a new layer of wood chips. Sometimes kestrels will evict starlings
from nest boxes. If this happens, the kestrels will use the starling's nesting
material (see photo of kestrel incubating).
- Records kept for each box on each visit will help to evaluate the sucess
of individual nest boxes, the nesting sucess of your kestrel population, and
ultimately, the sucess of your nest box program.
Previous Section -- The American Kestrel: North America's
Return to Contents
Next Section -- Iowa's Nest Box Program