The Eastern Bluebird Management Guide
The Eastern Bluebird is one of the smaller members of the thrush family. The male has a blue back, a rusty red breast, and the lower belly is white. The female is similar but the colors are not as bright. Young birds have a speckled breast with no red and are mostly gray in appearance. A little blue may show in the wings. The bluebird song is 3 or 4 soft gurgling notes. Their call is a cheerful chur-wi or tru-ly.
Bluebirds feed mainly on insects but will eat fruits and berries, especially in winter. They will come to a bird feeder to eat suet and will readily use a birdbath. Bluebirds are cavity nesters. They use old woodpecker holes and natural cavities in trees and posts. They cannot resist a birdhouse if it is of the proper size and in the right location. The range of the Eastern Bluebird is east of the Rockies from southern Canada to the Gulf States. Their close cousins, the Western Bluebird and Mountain Bluebird, are not found east of the Mississippi River. Most Eastern Bluebirds migrate into the southern part of their range in winter.
During the 1950's birdwatchers and ornithologists started to notice a decline in the number of Eastern Bluebirds. The decline has generally been attributed to a loss of good nesting habitat and sites, indiscriminate use of pesticides, and competition from other, more aggressive, cavity nesting species like House Sparrows and Starlings. In recent years a bluebird recovery has begun. This has been due to management programs carried out by organizations and individuals throughout the eastern states. The most successful management technique has been providing houses for nesting.
THE BLUEBIRD HOUSE
Specifications - Location - Installation
Bluebirds will use tree holes and other cavities of a variety of sizes and shapes, but studies have shown that they prefer nest holes that are generally 4 X 4 to 5 X 5 by about 8 inches deep. The entrance hole must be at least 1½ inches in diameter. The front should be hinged to provide for easy opening and cleaning. The 1½ inch hole should be in the front, 6 inches from the bottom. There should be holes in the bottom to allow for drainage. The house should be ventilated to help keep it cool in summer. This can be accomplished by leaving a space above the door or by drilling several holes slightly below the roof line.
Some manufacturers use copper or other metals on the outside of houses for durability or decorative purposes. This is not a good idea. These metal parts can get very hot in the summer sun, especially in the deep south. There is also a bluebird house on the market that does not have a roof. This is another lousy idea!
The location of the house is very important. Bluebirds prefer open grassy areas with enough trees or wires to provide perches. Pastures, open woods, and orchards make good locations. A golf course is a very good example of bluebird habitat. Avoid thick woods, large open areas with no trees, or open areas with very tall grass. The usual distance between houses is about 200 feet. Bluebirds are territorial and will usually not allow another pair to nest in the approximately 2 acres they claim as their own. There are records however of 2 pair of birds using houses that were nearly side by side.
There are those who suggest that the house should be installed facing north or east. This supposedly helps the house stay cooler in the summer heat. This is not really the case especially in the deep south. When the mid-afternoon temperature is 95 degrees the house is going to get hot regardless of the way it is facing. It is much more important to face the house toward a tree, shrub, or fence so the young birds will have perch to land on on when they take their first flight. If the house faces a broad expanse of lawn or open field they will probably wind up on the ground since the first flight is usually fairly short.
The house can be attached to a tree or post and can be from 4 to 15 feet above the ground. The ideal is to place the house on a post about 5 feet from the ground. At this height an adult can look into the house without having to use a ladder. A house on a post does not seem to attract as many roaches, ants, rats, and other nasty critters as a house on a tree. Using a post also allows you to put the house where you want it instead of being limited to a spot where a tree is growing.
BLUEBIRD MANAGEMENT
A good management program will help insure that the bluebirds using your houses will be successful in raising their families. Understanding the breeding cycle of the bluebird is essential to planning your management activities.
BLUEBIRD NESTING CHRONOLOGY
- Nest Cavity Search - The search for a nesting place may start as early as February in the deep south. The search will begin later in the northern states. The length of time it takes for the birds to find a site will depend on the availability of tree cavities or bird houses. The nest cavity may be found on the first day of the search or it may take up to 60 days for a suitable location to be found. At this stage of the nesting period the male and female birds will be seen near the house from time to time during the day. When a suitable nest cavity is found, the male claims the territory.
- Nest Building - It takes from 5-14 days for the birds to complete the nest. The female does most of the work. The male prefers to perch in a nearby tree and sing. Grass and straw are the preferred nest material. If you discover moss, fur, or sticks and leaves in a house, the nest is probably being built by one of the other small, cavity nesting species (Chickadee, Titmouse, Wren, Nuthatch).
- Egg Laying - Egg laying takes from 3 to 6 days. One light blue egg is laid each day until the clutch is complete. The most common clutch size is 5 eggs, but 3, 4, or 6 eggs is not uncommon. 2 or 7 eggs in a clutch is rare.
- Incubation - The female incubates the eggs for 13 or 14 days. She starts incubating on the day she completes the clutch. For this reason, the eggs will all hatch on the same day.
- Nestling Stage - The baby bluebirds will remain in the nest for approximately 15 days. They will be brooded by an adult bird every night, and on cool days until they are fully feathered. During the nestling period the youngsters will be fed by both parent birds. They do not leave the house during this time. All droppings are removed from the house except on the day the young birds fledge (fly from the nest). Once the young birds fledge they do not return to the nest.
- Fledgling Stage - At the end of the nestling period, the young birds fly from the nest. They will be fed by the parent birds for another 7 to 14 days. During this period you will see them in the vicinity of the house. Very soon after the nesting cycle has been completed the parent birds will start over. They may raise as many as 3 broods in a season. Certain management techniques should be practiced to help them along.
MANAGEMENT TECHNIQUES
- Observing The House - You can open the house to check the nest once or twice a week without distressing the birds. Frequent house checks will allow for quick discovery of problems, and make your record keeping more accurate.
- Cleaning The House - Clean the house before and after the nesting season and after each brood has left the nest. Bluebirds build a new nest for each brood. They will rebuild quicker if they have an empty cavity to nest in. They will sometimes refuse to use a house if it has an old nest in it, even if it is a nest they built. When they use a house with an old nest in it, they build a new nest on top of the old one.
- Insect & Predator Control - (These techniques are used only when problems arise)
Ants can be controlled by greasing the mounting pole or applying "Tree Tanglefoot" to the tree or pole. Other insects such as wasps can be removed physically, or controlled with pyrethrum spray or powder. If parasites are a problem, apply 1 teaspoon of 1% rotenone during the first few days of incubation. Do not use rotenone after the eggs have hatched. If eggs or nestlings disappear mysteriously a snake, raccoon, house cat, or other predator is usually the culprit. A metal baffle or some other type of barrier can be placed on the tree or pole to discourage these bandits from climbing to the house. Some nests will be lost to varmints in spite of all you can do. Remove the eggs, young, and nest of House Sparrows from the house. (House Sparrow eggs are slate-gray with dark blotches). Allow Chickadees, Titmice, and other species to raise their young.
- Record Keeping - A record should be kept on each of your bluebird houses. The record system should provide at a minimum the following information on each house.
1. The date of the start of the first nest and each successive nest.
2. The number of eggs in each nest.
3. The number of eggs that hatch in each nest.
4. The number of nestlings that survive long enough to fledge.
5. Problems with predators, insect pests, and disease.
Each house should be assigned a number so your record keeping will not become confused. At the end of the breeding season, you should total all the eggs laid, eggs hatched, and bluebirds fledged. It will be interesting to see if your numbers increase over the years as a result of your management program. Review your records occasionally to pinpoint problems. If a house is not used after 2 years, it should be moved to a different location.
ENJOY YOUR BLUEBIRDS!
Source: By Charles Kennedy - Alabama Wildbird Conservation Association