Parent bluebird feeding a grub to a nestling.
photo by Peggy Honda

Are bluebirds visiting your yard to forage for insects or seek a tree hole in which to nest? Installing a birdhouse can be beneficial and a source of much entertainment. But problems develop when proven methods of helping them are not followed. Below is what you need to know.

Bluebirds search for tree cavities in February and March and begin building their nests. In a healthy habitat dead trees and woodpeckers provide the tree holes they require. But, in Fullerton local birds need human help to find cavities they need for nesting. Certain birdhouses are acceptable substitutes, however, most birdhouses are not well-designed or are not placed in safe locations.

The right box in the right place is key.

A safe box for bluebirds is about 10″ tall  with an inside floor dimension of 5″ by 5″. The wood should be about 3/4″ thick and the hole should be 1-1/2″  or 1-9/16″ in diameter. It should have a door that opens for easy cleaning and have no perching post. A good box design is available at http://www.socalbluebirds.org.

A pair of breeding bluebirds needs about two acres of low grass. If your lawn and those nearby collectively provide approximately that amount, bluebirds may successfully breed.

Outdoor cats and nest boxes are a deadly combination.

Cats are not native American wildlife and native birds have not evolved with these excellent predators. Millions of birds are killed annually by cats. Locations where feral or pet cats roam are not place for a nest box.

Shaded locations can be life savers.

It is important to place the box in a well-shaded area because the internal temperature of the box can be substantially higher. Prolonged high temperatures can affect the health of parents and kill nestlings. Side-ventilation holes are beneficial. Painting boxes a light color to reflect heat is also recommended.

Busy feeders near nest boxes are risky.

Having a nest box in your yard while also enticing as many birds as possible with seed, mealworms, nectar, suet, bread, etc. increases stress for the nesting bluebirds. Feeders also draw snakes, rodents and hawks. It is safest to have no feeders if nest boxes are present.

Other dangers.

When birds weave materials like string, frayed blue tarps, ribbon, Easter grass, and yarn into their nest, strangulation or trapping can occur. Raccoons and snakes are frequent predators in many places and methods to deter them are necessary to bird survival. Argentine and Fire Ants are ubiquitous and must be kept out of boxes because they also kill birds. Other dangers include chimneys and vertical pipes. When the latter are 1-10 inches in diameter they attract songbirds looking for a cavity. The straight, smooth sides of the pipe traps birds. Options include removing the pipe, capping, screening or filling them with dirt, rocks or concrete.

More ways you can help bluebirds.

Did you know you can also help bluebirds by volunteering to monitor an existing trail of boxes already in use by bluebirds? These trails are usually in highly suitable habitats which ensure greater breeding success long term. Contact your nearest Bluebird Society.

Dead trees exceed the benefits of nest boxes.

In urban areas dying trees are removed by people for safety and aesthetic reasons and because they are unaware of their tremendous habitat value. It surprises many to learn that, in some cases, a dead tree can be safely managed and monitored. It’s important to first ask a certified arborist and tree-risk assessor if a dead tree needs to be removed completely, or perhaps if part of a dead limb in a live tree can be saved. Encouraging the safe retention and management of standing dead trees in appropriate cirumstances and locations is critical. Doing so benefits the health of urban forests overall and reduces reliance of birds on human made artificial cavities.

Healthy and diverse urban forests should continue to be an important goal for the benefit of all wildlife and people, and to offset climate change.

Resources

Learn more about dead tree selection and management or to order a Wildlife Tree sign for a safely managed dead tree, please visit http://www.CavityConservation.com

Explore the following websites for suggestions for predator guards and other resources for nest box owners: http://www.socalbluebirds.org   http://www.sialis.org  and http://www.nabluebirdsociety.org.

If a bird is injured or a baby bird has fallen from the nest learn what to do and not do by visiting: http://www.songbirdcareandeducation.org/foundababybird.html

To find a certified wildlife rehabilitation center that works with songbirds go to: https://www.wildlife.ca.gov/Conservation/Laboratories/Wildlife-Investigations/Rehab/Facilities