Helpful hints on:
Box monitoring
Box care
Competitors
Box pests
Faculty Advisors
Paul Matia
Sandra Ramsey
CentralDauphinHigh School
437 Piketown Road
Harrisburg, PA 17112
Material contained within this pamphlet is from:
Male Bluebird feeding fledgings
The Bluebirder's Timetable
Nest building: 1 - 6 days
Egg laying: 5 - 7 days
Incubation: 13 - 14 days
Fledging: 16 - 21 days
When Do Bluebirds Nest?
The breeding season for Bluebirds ranges between early April through mid-August. They typically nest 2 times per year and in good years with lots of food, they may make 3 “clutches”.
Nest boxes should be checked weekly throughout the breeding season to regulate competitors and parasites.
What is a Bluebird Nest like?
Bluebirds are cavity nesters. They build their nests in “cavities” in trees or in artificial houses. Bluebirds typically use woven grass, pine needles, straw, hair and sometimes feathers.
Typically there will be no seed heads, cigarette butts, strings, sticks, or other junk in a Bluebird nest. See Competing Species if you suspect the nest in your Bluebird nestbox is that of another species.
How many eggs per nest, and what do they look like? The eggs are laid one each day until the entire clutch is complete, usually 4-6 powder blue or, occasionally, white eggs (rarely)
The white eggs in the nest above are Bluebird eggs in a feather lined nest. Although rare, they do appear in this condition.
How long till they hatch? Incubation lasts approximately 12-14 days Incubation usually begins right after the last egg was laid, but sometimes the female will wait a day or two.
Determining the age of young bluebirds is extremely difficult. The size, weight, and development of nestling birds vary greatly and are dependent on food, weather, temperature, and the number of birds in a nest. Despite these variations, some common clues can help you approximate the age of nestling bluebirds.
Aging of Bluebird Nestlings
Day 1: Eyes closed; black down on head and
sometimes spine; young are a little
larger than egg.
Day 2-4: Eyes closed; body weight has at least
doubled; feathers begin to appear as
dark areas on wings and head (day 4).
Day 5-7: Eyes open as slits; feathers break
through skin on wings and head;
feathers begin to open (day 7).
Day 8-11: Eyes wide open; primary wing feathersstill opening; weight is 75 percent of
adult weight.
By day 11, wing featherson males may appear bright blue andon females, pale blue-gray.
Nestlingsmay preen a little.
Day 12-21: White eye ring; young actively stretching,preening, and flexing their wings.
Note: Opening the nest box after day 12 is notadvisable unless a problem arises. The increasinglyactive nestlings may fall or hop out of the nestbox, reducing their chances for survival.
COMPETITIVE SPECIES
Learn to recognize the nest and eggs of the house sparrow and remove them from yournest box.
House sparrow nests, eggs, adults, and young are not protected by law and may be legally removed or destroyed. It may take many weeks of removal to discourage house sparrows from using your bluebird box.
A house sparrow nest is very sloppy. It is made of coarse grass, rootlets, leaves, straw, and possibly bits of cloth and litter, which fill the cavity. It often has a domed roof when built in a nest box and may vary in size. The three to seven eggs are oval and white, gray or greenish, with irregular, brown speckles.
The female House Sparrow (below) is dull in color but look for the eye stripe in identification.
The Cowbird is what is known as a parasitic nester. It builds no nest of its own, but lays its eggs in the nests of other species, then leaves the incubation, feeding and care of its young to the host bird. Often the Cowbird will remove one of the hosts eggs from the nest prior to laying its own.
If a Cowbird lays an egg in a Bluebird nest, the Bluebirds may raise the Cowbird young at the expense of their own chicks.
The European Starling (EUST) is a formidable competitor to Bluebirds in the wild; however a man-made nestbox with a 1 1/2" opening will not admit a Starling.
Starlings may still compete with the Bluebird at the mealworm feeder. Several styles of feeders have been designed to discourage the Starling from entering.
The House Wren can be a problem for Bluebirds, as it frequently fills several desirable nesting sites with twigs, but only uses one nest.
It has also been known to enter nestboxes where Bluebirds are nesting, pecking holes in the Bluebird eggs.
Being a native songbird, however, it is a protected species, and its completed nest and/or eggs should never be disturbed. It is possible to discourage a House Wren from building in a specific Bluebird nestbox before the nest is complete by repeatedly emptying the box of the twigs that the House wren deposits there . But the best defense against House Wrens is to place the Bluebirds nestbox in a fairly open location, at least 100 feet from densely wooded areas, as the House Wren prefers to nest in or near wooded land.
The Titmouse (TUTI) is a native cavity nester and a very desirable nextbox tenant. They may nest in Bluebird boxes, but they are able to use boxes with smaller openings. If you have Titmice and Bluebirds competing for a nestbox, the Bluebirds will frequently win because they are the larger bird.
The nest of a Titmouse is often messy with pieces of paper and other debris along with loose leaves.
Chickadees, like Titmice, are very desirable nestbox tenants.
Chickadee nests are often heavily lined with feathers and mosses.
The Tree Swallow (TRES) is a beautiful bird welcomed by many bluebird nestbox owners. The two species can often be encouraged to nest in close proximity by providing nestboxes in pairs, placed 5 - 25 feet apart.