Bluebirds bring happiness and reduce pests in your garden

Guess what? Recent scientific studies have confirmed that seeing and hearing birds makes people happy! Science is just beginning to back up something that we humans have intuitively known for a very long time. A typical example is the blue bird, which has symbolized happiness in cultures around the world for centuries.

Two species of bluebirds call Butte County home. Classified as an uncommon resident, the mountain bluebird (Sialis currucoides) prefers grasslands at higher elevations while its slightly smaller cousin, the western bluebird (Sialis mexicana), inhabits open woodlands and coniferous forests and the parks. The western bluebird is the species commonly found nesting in our area and therefore the one you are most likely to encounter in your yard or garden.

“The Real Dirt” is a chronicle of various local Master Gardeners who are part of UC Butte County’s Master Gardeners.

A bluebird is likely to catch your eye with its bright plumage and cheerful song. Male western bluebirds are blue with gray underparts and a rusty red vest that extends over their backs. The female has a duller, more muted version of her mate’s coloration.

Western Bluebirds frequent forest edges and open understory that provide them with the visibility they need to hunt for food. They find feeding grounds in parks and schoolyards and along fields and golf courses. They hunt by dropping from low perches to the ground to capture invertebrate prey. Their summer diet, composed mainly of insects, makes them excellent allies for the landscape and the garden of the house; they will eat many beetles and caterpillars considered pests of vegetable and agricultural crops, as well as those pesky mosquitoes. Studies of their pest control potential confirm that they significantly reduce insects on vegetation and show promise as natural pest control agents in commercial vineyards and orchards as part of an integrated pest management program. pests.

You can welcome bluebirds to your garden by incorporating native plants into your flower beds and landscaping. Native plants not only provide habitat for insects considered beneficial to your garden, but are also more likely to provide the diverse insect community needed to support bluebird families during their summer breeding season. Avoiding pesticide use will be safer for birds and your community of beneficial insects, and with bluebirds in your garden, you may find that you don’t need pesticides in the first place.

  • Western Bluebird hatchlings and an unhatched egg in a nest. (Maren S. Smith / Contributor)

  • A western bluebird in a nest box. (Maren S. Smith / Contributor)

  • A western bluebird with lunch. (Maren S. Smith / Contributor)

  • A female western bluebird selects a berry. (Laurie Wilson, Wilson Nature Photography/Contributor)

In winter, western bluebirds flock and migrate short distances to take advantage of the seasonal availability of small fruits and berries, and some seeds. Some of the native berry-producing plants they prefer include mistletoe, toyon (Christmas berry or California holly), elderberry, California grape, serviceberry, red berry, juniper, and even juniper. poison oak. You can improve your landscape’s appeal to bluebirds by providing a year-round water source and native plants for bluebirds to eat in the winter. Other plants they may feed on include dogwood, pacific madrone, cherries (Prunus species), figs, California rose, California buckthorn, wax myrtle, manzanita, and lantana.

Another way to increase the potential for bluebirds on your property is to provide artificial nesting sites. As secondary cavity nesters, bluebirds are unable to dig their own nesting holes, but must rely on cavities created by other animals or the elements. The removal of dead and dying trees, both for construction and due to uncontrolled wildfires, has contributed to the decline of bluebird populations and affected many other cavity-nesting bird species, some of which compete with bluebirds for nesting sites. Be sure to check your diseased trees for nesting cavities before removing them and if you see bluebirds in your yard or immediate vicinity or think you have a good habitat, please consider setting up a nest box to help them.

If you have more than an acre of property, you may have room for multiple nesting boxes or even a trail of bluebird nesting boxes. Due to territoriality, bluebirds will not nest near other bluebirds, so if you are setting up more than one nest box, don’t expect more than one pair of bluebirds unless you have space to leave 200 to 300 meters between boxes. Pairs of boxes as close as 15 to 20 feet apart can provide nesting sites for a pair of bluebirds and a pair of oak tits or tree swallows (reducing their competition for sites nesting sites where natural cavities are rare).

Maintaining bluebird boxes can be a wonderfully rewarding experience that will bring you closer to nature. Be aware that different species of birds have their preferences when it comes to nesting boxes, but don’t let this caution put you off. Whether you choose a box to buy or make your own, following a few relatively simple guidelines will improve your ability to attract bluebirds and ensure they can raise their young safely and successfully.

Western Bluebird Nest Box Guidelines:

  • Use untreated pine or redwood (old fence boards can be recycled into birdhouses).
  • Keep the color and look natural and forgo an outdoor perch; birds need camouflage to avoid predation, and perches allow avian predators easier access to eggs and young.
  • The box should be eight to ten inches deep, with an interior cavity of about five and a half square inches; the entrance hole should one and a half inches in diameter, placed seven
    inches above the ground.
  • Provide insulation to keep nest boxes cool in the summer and warm in the winter by making sure the sides of the nest box are at least three-quarters of an inch thick.
  • The ventilation space under the roof and the holes in the bottom corners will keep the birds cool in the summer and dry in the rains.
  • Rough grooves under the nest on the inner surface help the birds out.
  • An opening side provides easy access for monitoring and cleaning old nests after each brood has fledged.
  • Mount the box at least five feet above the ground on a pole, if possible. Boxes can be attached to trees and fences, but this type of setup will allow predators easier access to the box.

To ward off pole-climbing predators (like raccoons), your birdhouse needs an overhanging roof, a wire cage around the entrance hole, and a predator deflector. Here are some instructions for creating a deflector:

Predator baffles are simple, inexpensive and effective:

  • Place the nest box out of wind and extreme sun, and away from busy areas or land that will be mowed, to minimize disturbance to the birds.
  • Keep the nest box pointed toward cover such as shrubs or trees, but free of vegetation so that adult birds have easy access.
  • Monitor your nest box for signs of active nesting (usually occurring between March and July) and consider becoming a citizen scientist to share your observations (see how below).
  • Leave nesting boxes in place all year round as bluebirds can take shelter in them in winter.

More information on bluebirds, woodworking plans for nest boxes, and additional resources can be found online at, the North American Bluebird Society web page /, and the California Bluebird Recovery Program at, among other bird conservation websites. The CBRP website shares a wealth of information and resources aimed at helping individuals select quality nest boxes and successfully install, maintain and monitor their nest boxes. Members also offer their expertise to advise the public and conduct training for those wishing to install and monitor nest boxes throughout the state.

Finally, you can contribute to citizen science by collecting data on how birds use your nest box and sharing it with CBRP and the Cornell Lab of Ornithology’s Nest Watch program (, an activity that is sure to delight young and old alike.

Let’s go bowling! The University of California Cooperative Extension (UCCE) in Butte County strives to meet the needs of Butte County residents like you in a variety of ways, including 4H, agricultural counselors, nutrition programs and physical activity and master gardeners.

Butte County Support Group UCCE will host their 18th Annual Bowl-A-Thon and Silent Auction on Saturday, March 12 from 6-9 p.m. Join us for a fun night! Get together with your friends and family to form a team of four bowlers; for a contribution of $300 per team, each bowler will receive three games of bowling and a free shoe rental. More information can be found on our web page or call the UCCE office at 538-7201.

Your tax-deductible donation will support UCCE programs and activities in Butte County.

The UC Butte County Master Gardeners are part of the University of California Cooperative Extension System, serving our community in a variety of ways, including 4-H, agricultural counselors, and nutrition and health programs. ‘physical activity. To learn more about the UCCE Butte County Master Gardeners and for help with gardening in our area, visit If you have a gardening question or problem, call the hotline at 538-7201 or email [email protected]