Mariton: More on Bird Houses

April 28, 2011

I am guilty of taking for granted that people understand why we utilize bird houses, or nest boxes. I stopped using the term Bird House some time ago. It gives the impression that birds use boxes to stay warm during nasty weather, or that they might live there all year. I have had birds sleep in nest boxes during the winter, but it is a temporary arrangement. A bird house is not a home.

Nest box more accurately describes a bird’s use of the structure: it builds its nest there. Nursery box is even more accurate. Because, once the young leave the nest and are actively flying, the birds (parents and children) don’t return. Even with Bluebirds, that might raise two broods in a summer, they rarely use the same box for the second brood. That is why it is not a bad idea to have a few boxes, even if they are closer together than what the “book” says they should be.

A nest box is just an artificial cavity. A cavity is just a hole in a tree. Why is this important?  Well 50 to 70 years ago, we noticed that species like Eastern Bluebirds, Chickadees, and Wood Ducks were disappearing from our yards, and our woods, and our creeks. At that time the forests in Pennsylvania were very young.  Firewood was at a premium.  Wooden fenceposts had been replaced with steel posts and wire. There just weren’t very many dead trees in the landscape with holes. Instead of waiting for the forest to mature, some people thought of testing artificial cavities. They worked! Whether they are made out of boards, PVC pipe (or even buckets for Wood Ducks) nest boxes have returned several species from the brink. Another conservation success story brought to your by people that observed nature and experimented, instead of wringing their hands.

Now here is the surprise for most people. Most birds don’t nest in bird houses.  Most birds build nests on tree branches, in crotches of trees, or even on the ground.  I don’t care how well you decorate a bird house, a Cardinal will not move in, because Cardinals aren’t cavity nesters.


Bluebirds, Tree Swallows, Chickadees, Tufted Titmouses, Woodpeckers, House Wrens, Nuthatches, Screech Owls, and Wood Ducks are a few of the cavity nesting species. They can all benefit from arificial nest boxes built to proper dimensions, and placed in the correct location and habitat.

(All photos by Carole Mebus.)