About us: We own the Wild Birds Unlimited nature shop in East Lansing, Michigan,
a store that provides a wide variety of supplies to help you enjoy the birdwatching hobby.

This blog was created to answer frequently asked questions & to share nature stories and photographs.
To contribute, email me at bloubird@gmail.com.

Friday, June 8, 2012

When to clean out a wren house

Great picture of house wren feeding a chick

We were lucky enough to have a wren family take up residence just outside our picture window.  What a joy to watch the parents tirelessly tend to their little ones!

Yesterday they flew the coop - babies and parents are now hanging out in our backyard, chirping and flitting about everywhere.  I want to encourage a second brood, so should I remove their used nest?  Do wrens reuse their nests or are the old ones considered too dirty?

Thanks, Kim Young
Chester, VA
Photographer:  Scott Young
This is a wonderful photo! Thank you for sharing.

You asked a very good question about nest cleaning. By cleaning out a nest box you help deter parasite infestation, a predator’s ability disturb a nest through the entrance hole and it’s a good time to evaluate the house’s condition. You should definitely clean out all bird houses at least once a year. I like to clean them in the fall after nesting season.

I encourage people to clean out bluebird boxes after each nesting or at least every fall because they aren’t good excavators. Bluebirds just build on top of old nests until the babies are sometimes are too close to the entrance hole and fall out before they are ready to fly.

Wrens can clean out their own box and the presence of a used House Wren nest may actually encourage wrens to re-nest. But you should check to make sure the nest doesn’t have any unhatched eggs or pests. If it’s a mess inside and the drainage holes are plugged go ahead and clean it out. You can leave some sticks below the house to help them rebuild. There is usually at least a two week window before they nest again.

To clean the nest box I usually place a plastic bag over the nest and just sweep it all in and twist the bag shut. You can rinse out the house with a water hose or diluted bleach spray. Make sure the drainage holes are unplugged and leave the house open to dry for a couple days. Finally dispose of the old nest in the trash and wash your hands thoroughly.

Thank you very much for contributing to the blog. Please feel free to write again. Sarah


Anonymous said...

I have wrens nesting in a decorative birdhouse that I never intended them to use! I am thrilled that this happened, and luckily there is a hole (covered with a movable piece of tin) in the back, so I can clean out the house when the wrens are done with it.
However, I don't believe there are drainage holes in the bottom of the house. Should I make some? Or doesn't it matter?
I don't think it matters to the wrens, as this is the second year they have used the house. (Not sure how many, if any, eggs were laid and hatched last year).

Anonymous said...

I have the same question about a decorative birdhouse we put up for decor & ended up with house wrens building a nest in it. We never saw any eggs or babies, but the wrens did use it regularly to sleep in. Will be a tad hard, but we can clean it out. Also wondered if we should drill holes in the bottom. Thx if anyone can help us out on this!

Wild Birds Unlimited Mid-Michigan said...

Many bird enthusiasts purchase a birdhouse at a local discount store and later find that it isn’t made to house birds properly. Things you should consider when purchasing a house:

1. Proper Drainage
Drain holes
Make sure your birdhouse has drain holes in the bottom to let out water. This is important to keep mold and bacteria from multiplying.

Roof overhang
Also, an inch or two of roof overhang will keep rain from entering the birdhouse entrance hole and will also help shade the interior on hot days.

2. Heating and Cooling
Just as in human homes, a birdhouse needs proper ventilation for heat escape in summer and thick walls for heat retention in winter.

Ventilation and insulation
Each birdhouse should have a slit or opening at the top of at least one side so hot air can escape during the summer. For the best insulation, most birders agree that wood makes a better birdhouse material than metal. It won't heat up as much in the hot months of summer, yet keeps warmth in during winter's cool months. Find one at least 3/4" thick. Though not usable for roosting in winter, clay or ceramic birdhouses insulate well in the warm months of summer.

3. Sizing
There are three main sizes to consider: entrance hole size, floor size, and entrance height.

Entrance hole size
The diameter opening determines which bird can enter the house. If the hole is too large, predators can reach in and disturb the nest. If the hole is too small, birds can’t gain access.

Floor size
Birds need a certain amount of floor space inside the house so the hatchlings have room to grow. For smaller songbirds like wrens, chickadees, titmice and nuthatches, 4" x 4" is usually fine. Larger birds need more floor space. Again, look for your target species' requirements.

Entrance height
This is measured from the floor of the box to the bottom of the entrance hole, and this distance is important for keeping eggs and hatchlings out of reach of predators that may approach the hole and try to scoop inside the house. Many species need 5" or more.

4. Safety
Safe birdhouses have a number of features that help protect the inhabitants from predators.

Perch-free entrance
Perches may look cute, but they simply give predators something to hold onto when approaching the entrance hole. Or, they invite invasive species to nest, which most people do not want. Since natural cavities such as tree trunks do not have perches, birds that will use nest boxes don't need a perch either. Another way to deter predators is to pole mount the nest box. Predators have a more difficult time climbing a thin metal pole than a tree trunk.

Enforcement around entrance hole
Some birdhouses feature a metal bracket around the entrance hole, which deters squirrels and other animals from enlarging the hole to gain access. Others have a thick piece of wood, with a cutout the same diameter as the hole, which in effect makes the entrance longer (called a predator guard) so that predators cannot scoop down into the box as easily.

Nontoxic materials
The best birdhouses are not finished with toxic paints or stains. Natural wood is the best choice for preventing the birds from having contact with anything toxic.

5. Mounting and Access
Your birdhouse must also keep your lifestyle in mind. It should be easy to mount, easy to clean and maintain and, if possible, easy for you to monitor the activities inside the box when practical.

Mounting device
It's easier to mount a birdhouse that includes a bracket or hanger for pole mounting or hanging. It simply saves you the time and trouble of trying to figure out how to install mounting hardware onto the birdhouse.

One side that opens
Birdhouses that you can open give you two advantages. You can keep them more sanitary because you can access the inside more easily for cleanout. Also, depending upon the style of opening, you can have a look at the activities inside the box, when practical.

Anonymous said...

I love wrens, I have five houses in my yard, One such house I have had 2 nestings thus far this year. The last family left on monday, last. Today another male is singing near the house, And is cleaning out the house, taking breaks and singing for a mate.I have neve seen wrens clean out a house. It is so cool. This is another reason that supports my love of them.