Monday, July 31, 2006

Bird Houses and Nesting Birds

Some people can put out a bird house and have it occupied immediately. I call that blind luck. I’ve tried a number of bird houses: wooden, gourd, rope, square, round, oblong.

I’ve had woodpeckers spend the day enlarging an entrance hole, only to have a mate take one look at the structure and say “Ummm, no.”
Last year the male Bewick’s wren built a nest in both a gourd and a coiled “lasso” bird house, but the female was not impressed with either.

For three years I’ve been putting out a titmouse house. The oak titmouse is a smallish gray bird with a crest. As cavity nesters who do not make the cavity themselves, the titmouse is dependent on finding old woodpecker cavities in dead trees. Such real estate is hard to find. City-dwelling humans readily cut down old and dead trees. With few nesting sites, the oak titmouse is in decline in southern California.

With this in mind, I purchased a bird house specifically designed to meet the needs of the titmouse pair that frequent my backyard. Many birds have a preference when it comes to bird house size, opening diameter, location height, and the direction the opening faces.

I came across a Cornell University publication that said most cavity nesting birds prefer their houses facing toward the northeast. With compass in hand, I aligned my houses. I raised the height, lowered the height. Put them in open areas, relocated them to overgrown areas. Occasionally, birds would do walkthroughs, but no one moved in.

When I read the titmouse prefers a nesting height between 11-15 feet. I went out and moved the nest box again. Within a few weeks, Bewick’s wrens moved in.

I think the deciding factor for the wrens was I had also added insect-laced suet to one of my feeders. The wrens were immediately attracted to this offering. For busy parents this was a readily available and dependable food source.

The wren pair worked diligently bringing food to their nestlings and once the youngsters fledged, taking them around the yard showing them where to hunt for insects. It was wonderful to watch the wrens as they raised two broods this spring in the titmouse house.

Now that everyone has fledged, it is time to be a good landlord and clean out the house.

It is amazing how two tiny wrens can build such an elaborate structure using only their beaks. The bottom layers are sticks, then twigs. Once they built up the height of the floor to the right depth from the entry door, they made a nest of soft grasses and leaves with a lining of dog hair and tufts of squirrel fur.

I thought the wrens were just chasing the squirrels to keep them away from the nest. Now it looks like they were actually plucking tufts of hair from squirrel tails.

It is amazing how clean the nest is. The parents take out the droppings in bundles and dispose of them away from the nest. This makes it harder for predators to find the hidden nest.

After cleaning it out, I carefully replaced the bird house back in its successful location. The wrens may be back next spring, but I have to admit I’m still hoping for the titmouse pair.

You don’t have to have a bird house to have nesting birds. Hummingbirds, California towhees, orioles and larger hawks build nests in trees and bushes. This year alone we had:

  • two nesting Allen’s hummingbirds, one on a low elm branch, one in a photinia shrub
  • red-shouldered hawks, in the high branches of a large eucalyptus
  • bushtits, high in a pine tree
  • California towhees, about 5 ft. high in an oleander
  • and of course the Bewick’s wrens in the titmouse house 12 ft. high in a Mexican pepper tree
Adding shrubs and trees to your landscaping will increase the real estate appeal for nesting birds. Provide reliable water and food, and your avian neighbors will abound.


Anonymous said...

Hrm. If the titmouses (titmice? titmeeces?) generally use a cavity previously created and/or occupied by another boid, mayn't it be true that they (the tit-whatever-the-plural-is) need some evidence that another bird was there before them? Maybe the new house has the wrong scent or something.


Unknown said...

I live in Redlands, located in Southern California. My property has many large historical trees in which many variety of birds frequent. My question: I have a lovely, large birdhouse on a 7' post with a total of 6 entry holes surrounding the house. Where is the best place for this birdhouse? Away from the trees in an open spot? What kind of birds will this type of house attract?

Keri Dearborn said...

The titmouse uses another birds cavity nest because it can't hollow out a tree cavity like a woodpecker does. If the cavity suits the titmouse's needs, it will move in. It doesn't need evidence that another bird has used it. Bewick's wren operate in the same way.

The birdhouse that Julie from Redlands is referring to is for communal nesting birds. Birds like swifts and swallows that like the protection of the group when nesting. These bird species typically nest more in the open so that all eyes of the community can see the nest location for a distance. A an "apartment-style" bird house like this needs to be in the open and near a meadow or pond where the parent birds can find the small insects that are needed for food.