FAQ

When the first settlers arrived, the Eastern Bluebird was as numerous as robins are today. This azure bird with the rusty breast, considered by many as the harbinger of spring, was proposed as the New York state bird in 1928. However, it wasn’t until 1970, when its numbers were down by 92%, that it became the state bird. Thanks to articles that raised awareness about the plight of the bluebird, hundreds of people installed nest boxes, helping to increase their population. See the full story here.

Bluebirds do not make their nest on tree branches. They are secondary “cavity” nesting birds, which means they build their nests in natural cavities such as holes in trees, wooden fence posts, or those created by woodpeckers. Loss of habitat and natural cavities due to dead tree removal and increased activity of invasive species made bluebird survival a matter of providing nest boxes, which they readily accept as nesting sites. References: Getting Started with Bluebirds; Setting Up Nestboxes

Ideal placement for a nestbox must allow for 2-25 acres of territory that bluebirds will defend from other bluebirds. It should be at least 100 yards away from another nestbox. If your property is much smaller than this, adjacent open property may allow you to have a successful nesting site. Place the nest box at least 50 feet out from trees and bushes to discourage House Wren intrusion. If there are English House Sparrows in your area, it may be better not to install a nest box. House sparrows are invasive, non-native birds that destroy bluebird nests and young. Allowing them to nest in your nest box would be damaging to bluebird recovery. References: Getting Started with Bluebirds and How to Properly Set Up Your Bluebird Nest Box; Fact Sheet: House Sparrow Control

Placing the nest box in an open area, more than 50-100 feet away from shrubs, leafy vines, wood piles, and brush, will discourage wrens. They do not like to fly over long open areas. Wrens build a readily recognizable stick nest, which should be removed from your bluebird nest box if there is no nesting cup present. Weekly or more frequent monitoring of boxes is necessary since wrens can build a nest and lay eggs very quickly. In a situation where the battle seems lost to the wrens, replace the bluebird nestbox with a small wren box (1 ¼” opening). House Wrens are a native species, so in the face of their persistence, having them in the yard singing away is not a bad thing if you cannot get bluebirds! Reference: Sialis.org House Wren Management

There are many possible causes of death in nestlings. This is one area where close monitoring of your nestboxes is very important, followed by examination of the nestbox and nest. Some possible reasons for nestling loss:

1. Abandonment by the female (her death or injury) in the first week of life
2. Cold, damp weather making it difficult for the adults to procure food for the nestlings
3. Predation by other birds: house sparrows or wrens
4. Poorly constructed nestbox allowing either overheating, freezing, or leaks, leading to wet nests. (Download files: Bluebird Nesting Boxes; NABS Nest Box specifications)
5. Disease, heavy parasitism (Download: Blowflies and Bluebirds)
6. Reference: Sialis.org Should I remove a dead nestling?

Unhatched eggs are often pushed to the side of the nest or down into it. Dead young may also be pushed to the side. Parents remove or consume egg shells of hatchlings, as they do with their fecal sacs. Monitoring the nest boxes every 5-7 days allows you to clean out dead young and help improve the prospects of the remaining live young by removing a source of infection or parasitism. After the young have fledged, the old nest should be removed and the box thoroughly cleaned out. Reference: Should I remove a dead nestling?

Right after fledging, the young are fed and then taught to feed on their own by their parents, usually in an area near their nest site. They will be seen as family flocks of 6-8 among the trees near their nest site. Whether bluebirds move away from your area or stay around usually depends on weather and food availability, sudden loss of habitat, and your area of the country. Bluebirds will stay in a breeding area as long as they can procure food (insects in the summer and berries of many sorts in the colder months when insect numbers are down). If the weather becomes continually wet and cold, they will move to areas where they have adequate food and warmth. Males try to stay all winter so they can reclaim their territory early in the spring. You may be visited by bluebirds that arrived from another area on their way to wintering grounds. Unless you can identify them by bands, you cannot tell them from residents.

In the early spring, it is not uncommon to see wasps in nestboxes. They usually appear groggy from the cold, which makes it easier to simply scrape them out of the box with a flat tool like a spatula. With warmer weather, they may build a nest and become more aggressive. Wait until almost dark, or a cool morning, when they are subdued, and use your spatula to remove the nest. Keep them out by rubbing Ivory soap into the roof of the nest box to make it difficult for them to attach a nest. Do not use insecticides. If you are allergic to stings, do not attempt this - get help. The native paper wasp has its place in our ecosystem, but not in our nest boxes. The European paper wasp is an alien and much more aggressive. Online sites will help you identify them.

If your boxes are attracting house sparrows, they should be relocated if possible. Examples of areas not suitable for bluebird nest boxes: around suburban houses, farmsteads, chicken coops/yards, livestock feedlots, and old buildings. It might be wiser to install house wren boxes, which will attract that native bird, and because of the smaller opening, will keep house sparrows out and prevent them from increasing their population in your area.

References:  Sialis.org - Managing House Sparrows; Sialis.org—Sparrow Spookers; A House Sparrow Advisory for Property Owner; Fact Sheet: House Sparrow Control

Red-bellied Woodpeckers, Downy Woodpeckers, and flying squirrels will try to make the openings larger. A metal guard plate with a 1 ½” opening can be carefully placed over the opening so it does not restrict the bluebird’s entry and will discourage this chipping.

Missing eggs are most likely due to predation by:

• House Wrens
• House sparrows
• Raccoons
• Snakes
• Other bird species

Using a Noel wire predator guard to protect the box opening from cats and raccoons, together with a snake baffle on the pole, can be very helpful. Reference: Predator Control

75% or more of their diet consists of insects during the months they are available. When insects are not available, bluebirds eat berries and fruits from trees and bushes such as sumac, bittersweet, bayberry, wineberry, white cedar, holly, dogwood, etc. Black cherry seeds (pits) and ground snail shells have often been seen in their nest after fledging. Reference: Plantings for Eastern Bluebirds

It depends. Unpainted natural wood, especially cedar, is acceptable and works very well. Pine is a common and inexpensive building material, but if left unpainted, it does not weather well, and the box will have a shorter life. The exterior of the nest box may be painted with a non-toxic (latex) paint. Allow at least a week for it to dry and dissipate any odor before installing the box. Painting the top of the nest box white will help reflect sunlight and reduce heat absorption, thus keeping the box cooler. The inside of a box should never be painted. Reference: NABS Nest Box Specifications

The female Eastern Bluebird lays one egg a day - they rarely skip a day. Checking the nest box daily during egg laying will tell you whether she came back the next day or not. If the clutch was finished, we recommend waiting 13-14 days to see if the eggs hatch, since you may not be there to see when she returns or leaves the nestbox. Make sure you have counted the number of days properly and realize they do not always go by the book.

In New York state, bluebird movement depends on weather conditions and the availability of food. They may move to warmer areas where food is more plentiful in times of severe winter weather. We typically see males throughout the winter. The young and females seem to leave the area for more southerly locations, although cameras placed at nesting sites have recorded birds of the most recent year late into the winter. Wintering bluebirds have been seen at the forest edge, around houses, and even on wide open spits of land jutting out into marine bays. In some warmer sections of the country, both sexes stay year-round and have more clutches.  (Download Wintering Bluebirds May Need Help and Winter Food For Bluebirds)

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