It’s bluebird box time in the Sierra Foothills |

It’s bluebird box time in the Sierra Foothills

Male bluebirds are taking on their brilliant blue colors to attract mates for the spring.

Because of this, the Sierra Foothills Audubon Society’s nest box program is getting ready for another season of nesting bluebirds. Bluebird monitors with nest boxes in place are cleaning out the remains of last year’s nests.

The importance of having a clean nest box was shown recently in an issue of Auk. Stanback and Ford of the Biology Department at Davidson College observed: “Bluebirds are willing to switch nest sites to minimize parasitism. Bluebirds prefer successful (previously used) cavities but only if they are clean.” Wasps and bees nesting in bird boxes will prevent birds from using them. It is necessary to remove these nests and open the boxes up for a few days to eliminate these pests.

Free nest boxes will again be available this year, thanks to the efforts of the Welcome Wagon’s woodworking group. Led by Milt Schmidt with liaison Hindi Greenberg, they are producing nest boxes from scrap sheathing and fencing material. Contact Jim Groeser at 432-6596 or at lgroeser@, and he’ll arrange to get one to you.

Monitors are also getting the forms ready to record their observations this year. These records are an important part of the annual program indicating the breeding success of different species and highlighting the presence of predators. Individual nest box records are available on the Web site for downloading and printing ( You can also contact Jim Groeser about this. Plans for building your own boxes are also available on the Web site.

Bluebirds are insect eaters and prefer open meadows or pastures with an abundant supply of bugs and worms for their homes. They are also quite territorial and will not locate within a hundred yards of another nest. Thus, only large meadows are suitable for more than one nest box. Nest boxes should be placed on a smooth pole or hung from a low tree branch to minimize predation from animals like raccoons and snakes. Preventative measures are necessary if nest predation becomes rampant. Regular monitoring reveals predators’ activities.

The final report from last year’s bluebird boxes shows that we fledged 388 western bluebirds and 123 mountain bluebirds. Eighty-year-old Barbara Moore, with help from Patty Evans and Ann McBride, monitors the 120 boxes she built and sited in the Russell Valley.

She was the only person to provide boxes for mountain bluebirds in California. The next most productive species in our boxes was the tree swallow. Three hundred and twelve new tree swallows emerged from 86 nests this year. Plain titmice produced 57 fledglings, while we added 36 new mountain chickadees to the environment.

These numbers are from 29 monitors who sent in their reports from a total of 277 boxes. Just over three- quarters of the 506 bluebird eggs produced fledglings. Bluebirds averaged slightly fewer than five eggs per nest. We did have more reports of predation of nestling chicks this year.

To all of you who monitored your boxes to no avail this year, let me quote a few lines from Vince Palomba in Penn Valley: “A pair of bluebirds nested in my box this spring. … I saw two young ones leave the box and join the parent birds. I did not have the opportunity to see if there were any other young birds. This was the first time I had bluebirds in my bird box in five years.”

Walt Carnahan is president of the Sierra Foothills Audubon Society.

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