Eastern Bluebird (Sialia sialis)
|Bluebirds occur throughout much of North America. In the spring and summer they look inside the small holes of branches and tree trunks to build their grass nests. Occassionally, they will choose an exposed cavity or a broken tree snag that is open on top.
|In many areas natural cavities are missing due to the downing of trees or have been eliminated due to tree pruning. Nest boxes may be put out to simulate natural wooden cavities and are often accepted by bluebirds.
|The house sparrow is a recent inhabitant of this continent and has competed viciously with the bluebird often killing young and adult birds while they are in the nesting cavity. Those nest boxes with open tops may help to disinterest the house sparrow from competing.
Woodpeckers (Family Picidae)
|Woodpeckers peck at wood. They do it to uncover insects that hide under the bark. They do it to carve out small hollows in tree trunks to use as homes. And sometimes they do it as a way of talking to each other. In the early spring they can be heard hard at work making nest sites in the sides of tall trees. Other birds are sometimes interested in their energetic occupation.
|The European starling which was brought to North America in the nineteenth century also likes to nest in hollow cavities in trees. But the starling cannot excavate the wood, so it watches the woodpeckers and waits for them to finish. Once the woodpecker is done, the starling comes and evicts it from its home. Now the woodpecker must start all over again at a new tree. And then more starlings come and chase the woodpecker once more.
|In order to help the woodpecker overcome the problem. caused by introducing this bird to the western hemisphere, Native America has designed an artificial nest box with a clear plastic shield: "The Woodpecker Protector". Woodpeckers climb up the front of the box, up under the shield, and into the entrance hole.
|Once inside the woodpecker is now protected from intrusions by the starlings. It is safe to nest and incubate. The young woodpeckers wait inside for food and grow large and full of feathers. Ordinarily it is dark inside the cavity and the young practice stretching their wings and calling.
|The parents bring food into the nest box for the young. And when the parents leave, they must also remove the droppings of the young to keep the inside of the nest box clean. They carry the fecal sacs of the young out of the nest box and fly it to a spot far from the nest.
|Starlings cannot climb up vertical surfaces like woodpeckers can and so cannot get into the shielded nest box. They look to fly directly into the entrance hole and are thus prevented from using these nest boxes.