For the Birds…
Preparing artificial nesting structures for Spring
by Josh Brandt, Wildlife Area Manager
Cerro Gordo County Conservation Board
To improve nesting success for some of our avian friends such as wood ducks and bluebirds, the Cerro Gordo County Conservation Board (CGCCB) has installed artificial nesting structures in county wildlife areas, parks, and roadside prairies. If you have some of these structures on your property and have not yet prepared for this Spring’s nesting season, now is definitely the time!
During the last few months CGCCB staff has been preparing for the arrival of breeding wood ducks and bluebirds by cleaning out and preparing their nesting boxes. Wood ducks are cavity nesters that prefer to build their nests in hollowed out trees near water. They will however, readily use artificial boxes constructed from wood, metal, or plastic. Wood ducks arrive in Southern Iowa as soon as late February, and will most likely make their way to North Iowa by early to mid March in search of a place to nest. In preparation for their arrival, nesting material from the previous season is cleaned out, along with egg fragments and other debris, and the bottom of the nesting box is refilled with fresh wood shavings. Wood ducks will rarely bring new nesting material to the box, so adding the wood shavings is a critical step to promote successful usage of the structure. This is a good time to inspect the box for damages, make any needed repairs, clear access by trimming any obstructing tree limbs, and minimize access points for predators. Cleaning out the boxes also provides the opportunity to track and inventory the success of the boxes from year to year. The Conservation Board has installed and regularly monitors over 180 wood duck boxes on 20 areas. During an average nesting season approximately ½ of the nesting structures are utilized by wood ducks. A typical hen wood duck will lay 10 or more eggs in a clutch, and will regularly produce two broods per year, so a little simple math can demonstrate the significant local impact we can have on the wood duck population.
The Eastern Bluebird is another species that will often nest in man-made structures. Bluebird boxes are typically constructed from wood (mostly cedar) and installed in native or restored prairies and grasslands. Many CGCCB areas and roadsides are home to these nesting structures and must be monitored annually as well. It is common practice to open the door on Bluebird boxes following the nesting season, clean out the old nesting material, and leave it open throughout the Fall and Winter months. This prevents mice from taking up residence inside the box. As we make our way into the Spring months, the boxes need to be closed to prepare for the arrival of migrating Bluebirds. No nesting material is added to these boxes, as the Eastern Bluebird constructs it’s own tidy nest with nearby grass.
If you have a natural area on your property that can support breeding populations of wood ducks or bluebirds, consider adding a nesting structure to give them additional opportunities for successful reproduction. There are numerous products that are commercially available for purchase, or you can construct your own boxes. Construction plans are available for both wood duck and bluebird boxes online or at the Lime Creek Nature Center.
