Check Your Bluebird Boxes

2/11/09  February is the time to clean and repair your bluebird boxes for the new nesting season. During this time, clean out any old nest material that has been in place over the winter. Also, repair any damages that may have enlarged the entrance hole and be sure that a predator guard is in place. The use of a sticky pest barrier on the pole below the nest box can help prevent fire ants from reaching your fledglings.  A product called Tangle Foot can be ordered on line or is available at some nurseries. 

Once the bluebird box is cleaned out, start monitoring the bluebird box at regular intervals to determine how productive your boxes are and to observe any problems that may develop.  The monitoring process can be rewarding by seeing the boxes that you installed being used.

Starting in March, you can check boxes once a week and continue to do so through July.  To check a box, tap the box before opening it so the female can leave if she is inside.  She will return after a short time.  While monitoring, look for evidence of nest building, eggs, or any other signs of bird activity.  Record when nest building begins, when and how many eggs are present, and when and how many birds hatch. Be watchful of non-native birds such as House Sparrow’s building nest. House sparrow nests are not as well built as those of bluebirds and the nest are littered with fecal material. You can remove the nest of house sparrows, but by law do not remove the nests of native species like wrens, titmice, swallows, and chickadees.

During the monitoring process there are several periods in which you must be careful not to disturb the box. The first period is during the first three days of egg laying, do not disturb the female during the morning hours since this is when laying occurs. Just remember that when you see nest construction nearly completed, start checking the box in the afternoon. The second period in which you should not disturb is the 3 day period just before you expect the birds to fledge. Bluebirds normally fledge when they are 17-20 days old, so to be safe do not check on them after about day 14.  A disturbance at this time can cause the young to fledge prematurely, in which they could starve are be vulnerable to predators.

After the young birds leave, clean out the nest material so re-nesting can occur.  Bluebirds will build new nests on top of old ones and successfully bring off broods.  The problem with this is that the second nest is higher in the box and can be more easily reached by a predator like a cat or raccoon.  After the last brood leaves in late summer, leave nesting material in the box over the winter.  This old material provides insulation for birds taking refuge in the box on cold winter nights.   During cold weather, many individuals may ‘pile-up’ in a single box to stay warm.