The female lays one egg a day. After she lays the last egg there is a two week gestation period before hatching. (Incubation does not start untilallthe eggs are laid.)
From the time they hatch to the time they fledge is approximately 21 days.
Short answer --- About 5 inches. :-) Blue Jays are ten to eleven inches long from tip of beak to tip of tail. The Western Bluebird is 5 and 1/2 inches long. The Scrub Jay has blue wings, tail and some on the upper part of the head. They show a lot of grey on the throat and breast. Stellar's Jays are mostly deep blue with a very prominent black topnotch. Both are noisy gregarious birds which tend to monopolize bird feeders and can be a real nuisance. Neither have any red on the breast. Western Bluebirds are about half the size of the jays - about the size of sparrows or slightly larger than Juncos. Bluebirds eat primarily insects and do not come to bird feeders where other birds are eating seeds or grain. The male Bluebird has very deep blue feathers on the head, wings, back and tail. Western Bluebirds have distinct rusty red breasts and usually have some rust color across the shoulder area.
If you live in the Willamette Valley or Oregon, you may see your bluebirds all winter long. Our population does not migrate, though they do flock up and move to lower elevations in the winter. Generally, a pair of bluebirds that nests successfully will return to the same area to nest in subsequent years. Even if one of the pair dies during the winter, the other bird may return with a new mate. Also, the male offspring will also tend to return to the area in which they hatched, bringing their own mates. The female offspring generally disperse over the winter and, if they find a mate, follow him to his natal site.
Bluebirds generally mate the year after they hatch. Often they are less than one year old. It's a good thing they get started early as bluebirds do not live very long.
You can put up nest boxes for bluebirds anytime. However, the best time is in the fall or winter. Bluebirds prefer a weathered box over a brand new one, and they begin checking out boxes as early as February or March.
There is no way to completely protect bluebird nests from predators.However, there are several things that you can do to reduce the risk of predation.
Avian predators:You can minimize predation by starlings, jays and kestrels by using nest boxes that are approved by the North American Bluebird Society. In the Willamette Valley, we recommend that nest boxes have an entrance hole that is 1 ½" in diameter. This is too small to admit the larger birds. The nest boxes need to have sufficient depth below the entrance hole to keep these birds from reaching eggs or chicks by sticking their heads into the nest box. Cleaning out old nests after the young fledge will also help keep the next nest that is built low enough to protect eggs and young.
There are two other avian predators that are small enough to enter a bluebird nest box. A house wren may peck holes in the eggs of other birds that arenesting in its territory. The best defense against house wrens is to place the nest box in an open area far away from brush and shrubs. House wrens are native birds that are protected by law. Their nests and eggs should not be disturbed.
House sparrows may peck holes in the eggs of other birds, kill nestlings by pecking their skulls or eyes and even kill adult birds if they find them in the nest box. The best defense against house sparrows is to place the nest box in an open area away from barns and other buildings where house sparrows are present. This non-native bird is so common that it is difficult to avoid them. You next line of defense is to remove house sparrow nests and eggs wherever you encounter them.
Animal predators:House cats and raccoons are the most common animal predators. The best way to protect bluebirds from these predators is to mount the nest box on a metal or pvc pole. Cats can not climb these poles. If raccoons are a real threat, multi-purpose lithium grease on the poles works great. This may also help todeter snakes.
If you can mount the nest box on a metal pole, you can try cone-shaped metal baffles mounted under the nest box or wire tunnels (noel guard) attached to the entrance hole.
Details for these and other predator control devices are available on the North American Bluebird Society web site under "Fact Sheets." You can find the NABS web site at www.nabluebirdsociety.org
Bluebirds are really grassland birds. It is difficult to attract them to urban or heavily wooded property. Most bluebirds prefer open fields with one or two large oak trees, pastures, vineyards, old orchards or large mowed yards with selected medium-sized trees for nest guarding. Nest boxes should be placed out in the open on fence posts or metal poles not nestled into groves of trees.
Bluebirds are primarily insect eaters. They do like berries, but they are rarely attracted to the typical bird feeding stations that offer a variety of seeds. Bluebirds feed primarily on the ground-like the robin, to whom they are related. They like spiders, crickets, ants, grubs and small worms. Once bluebirds start nesting, you can offer mealworms to help the parent birds feed their nestlings during cold, rainy weather. The most effective way to attract bluebirds is planting native berry producing plants.
Bluebirds in the Lower Willamette Valley do not migrate south for the winter. They tend to join small flocks and forage on insects and dried berries. The will move to lower elevations if the winter is very cold. Sometimes they will roost over night in a nest box during the bitterest weather.
Bluebird males establish and defend feeding territories to which they bring their mate. It is the female bluebird's job to choose the best nest box within that territory. A successful pair may return year after year to the same area, often the same next box. When one of the pair dies over the winter, the remaining bluebird may return with a new mate or one of the pair's male offspring may take over the nesting territory.