For the birds: Swallows appreciate a nice spring cleaning

Posted: Friday, May 09, 2003

As the birch leaves emerge and sprinkle green onto our passing winter landscape, I find myself digging into the garage and dusting off my golf clubs. Then, I hear a subtle chirping reminder that I have other duties to perform before I play.

Last spring, I put up several birdhouses around my property and was rewarded with two families of tree swallows darting around the yard, consuming large quantities of flying insects. You know the ones I am talking about. With such beautiful weather so far this spring I have yet to hear the M word, but we all know they are coming. Swarms of little buzzing bloodsuckers will soon be drowning even the sounds of birds. Your 6 a.m. wake-up call may soon be replaced with sleepless nights of swinging into the darkness as they buzz by your ear.

From the garage I heard the familiar chirping of swallows scouting out nest sites in my backyard. I realized that I had neglected to clean the birdhouses from the previous year's use.

Many people ask me if it is really that important to clean the houses out every year. In the wild, who cleans out the old nest materials? Well, this is my theory on the subject.

There is no shortage of possible nest sites in the wild. If swallows were unsatisfied with the cleanliness of last year's nest, they would simply move on and find a new site. Unfortunately for me, that may not be in the vicinity of my yard where I cheer at every mosquito picked out of the sky by these fearless fliers.

So why clean the nests, anyway? There are several compelling reasons why we should remove the old material and scrub out the debris from the old nests. Bird nests are inherently dirty spots; they often become the home of many parasites, such as feather mites and fleas. Over time, a nest used repeatedly can become completely infested with parasites. During the summer, parasite eggs are laid in the nest materials and then the following year they hatch and completely infest the new hatchling swallows.

In some cases this can actually reduce the survivorship of birds in the nest.

Since I put up the nest box in order to entice the birds into my yard, I think it is only fair to try and keep the box tidy for them each year.

I have also noticed that the swallows in my yard pride themselves on the quality of nest materials they collect. If there is no room for new materials due to excess leftover debris, they will simply move on. Some prefer to line their nests with moose hair, while others favor fine dry grass. Nests in my yard are often lined with delicate blonde hair from my golden retrievers!

If you are new to the game of nest boxes, here are a few pointers. It is quite a game, by the way. I know people that have put up nest boxes in their yard for years and have yet to attract any summer residents. They buy complicated, beautiful nest boxes and erect them everywhere, but just don't seem to entice any birds.

Other folks I know hang small cardboard boxes under their eaves and cut a hole in the box with a pocketknife. They have four or five families of both tree and violet-green swallows every year.

Like real estate, I think the trick is location. You may read in books that the nests have to be facing in a particular direction, like south facing, to provide additional warmth. I find this is less critical than what is in front of the nest and what the nest is secured to. I have placed boxes in trees, secured them to the house and even erected freestanding poles.

The best luck I have had is with boxes tucked up under the eaves on the corner of the house. Nest boxes that are attached to trees are often less desirable due to predators like the red squirrel. On most houses it is pretty difficult for a squirrel to predate a nest suspended under the eaves.

Swallows prefer to come flying into the box low to the ground and then swoop up to the nest hole with a straight in approach. If your nest box is on the back of the garage and you only have 15 feet to the wood line, you will probably not have a lot of success enticing swallows. They want a wide-open approach.

Lastly, the site you choose should be free of unpredictable disturbances. If you have people coming in and out of your front door, this would not work well for a nesting site. Swallows are fairly tolerant of humans, but they have their limits. Disturbances that force both parents to leave the nest box and fly around result in unsuccessful nests.

For you, this means the birds will lose interest in your yard and will spend the summer hawking mosquitoes in my yard.

Todd Eskelin is a biological technician at the Kenai National Wildlife Refuge. He specializes in birds and has conducted research on songbirds in many areas of the state.

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Previous Refuge Notebook articles can be viewed on the refuge Web site at

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