How to be a good nest box landlord

Part of being a responsible nest box landlord is your willingness to watch out for your tenants.  Some of your landlord duties include:

•     Checking the box for other species, such as starlings or common sparrows that may use it if not discouraged from doing so.

•     Monitoring the activity in the nest box to determine if predators are gaining access.

•     Cleaning the nest box out after every nesting season.  This is necessary for ridding the box of dirty nest materials, fecal matter, and nest parasites.

•     Repairing damaged nest boxes and replacing irreparable ones.

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.

Always work quietly and efficiently to minimize stress to the birds.  Slowly and quietly open the box, and check the contents.  Be careful, you may find something other than a bird inside.  Don’t be surprised to see squirrels, bluebirds, starlings, other birds, a mouse, snake, insects or even honey bees.

Always wear a dust mask when cleaning out nest boxes.  Look for fleas, flies, mites, larvae, and lice in the bottom of the box. 

If you find insects or parasites, your first reaction may be to grab the nearest can of insect spray.  If you do, use only insecticides known to be safe around birds: 1 percent rotenone powder or pyrethrin spray.  You can also use a 2 percent bleach/water solution to kill any nest parasites.  If wasps are a problem, coat the inside top of the box with a bar of soap.

During the nesting season, the box should be opened carefully and quietly to make sure European starlings have not laid their eggs in the box.  Even if kestrels are present in the box, it is okay to quietly inspect the box a few times during this season.  Occasional checking of the nest will not cause the kestrels to abandon the nest. 

European starlings may be a persistent problem because they often nest in kestrel nest boxes. Starlings replace or cover wood chips with grass and other material and lay five, six or seven greenish white to bluish white eggs. Kestrel eggs are usually white, pinkish-white, or cinnamon-colored, and they are evenly covered with small spots of brown. 

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.  Starlings are an unprotected species.

Kestrels normally lay a clutch of five eggs.  If you are unsure about which bird’s eggs are in the box, take a few minutes and watch from a distance to see which species is using the box.  If the eggs belong to starlings, remove the eggs and discard them.  Also, remove any nest materials the starlings may have brought into the nest box.

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.

Four downy chicks with female kestrel

Photo credit:  The Kestrel Box, an Arizona non-profit corporation

 Avoid checking nest boxes:

•    In the morning during egg-laying.  Nest boxes should be checked in the afternoon, since most females lay their eggs in the morning and are absent from the nests in the afternoon.

•    During the first few days of incubation.  If necessary, observe the box from a distance and approach only when the female leaves the nest to feed.

•    When young are close to fledging.  When the young are disturbed during this stage, they leave the nest prematurely.  Young that fledge prematurely do not stay in the nest box despite attempts to return them, and their survival rates are very low.

•    During inclement weather.  If the weather is cold, damp, or rainy, postpone checking the box until another day.  Checking boxes during this time can be very stressful for the birds.  

While not a requirement of Iowa's American Kestrel Nest Box Program, checking on your nest box every so often and keeping records of your observations and discoveries is one of the most rewarding parts of the program.  

You'll be surprised from visit to visit as you watch the kestrels diving for their prey, feeding their young, and sitting patiently perched on the fence post. 

Click on the "Monitoring and Record keeping" button to find out how to keep a journal of your observations and a recommended list of supplies to take along on each visit.