If you’re managing a bluebird nest box, chickadee nest box or other native cavity bird and have seen a house wren in your yard or even enter your nest box, you might be wondering if they’re a threat and how to minimize the house wren threat to your bluebirds.
If you have a house wren going near your bluebird or chickadee nest box, the first step you can take is to add a second nest box, after that optimizing nest box location, adding a wren guard, keeping the wren busy and a few other steps will help keep the peace between bluebirds and house wrens.
In this article, we’ll be highlighting 8 tips for what you should do if you’ve spotted a house wren near your bluebird or chickadee nest box.
But Before we do that, it is extremely important for us to remind everyone that house wrens are native cavity nesting birds and are therefore federally protected. Furthermore, we encourage everyone here to have a heart for backyard bird conservation, and that means protecting native wild birds.
House wrens are definitely a threat to nesting bluebirds, chickadees, tree swallows and other smaller cavity birds.
They are known for building dummy nests, and that means they often invade active nest boxes and throw the eggs out or even very young nestlings. This invasion can be the ruin of an entire brood.
Knowing this can make it hard for us to sometimes advocate for house wrens. But we must protect them as much as any other cavity bird. And fortunately, there are ways to keep the peace between house wrens and other native cavity birds.
These tips will not guarantee peace. But they can certainly set you up for a lot more success.
Quick list of tips for when you’re trying to keep the peace between bluebirds and house wrens:
- Immediately put up a second nest box.
- Optimize the location of each nest box – one in a location appealing to bluebirds and one in a location appealing to house wrens.
- Distance each nest box at least 30 feet apart, if not more. You can sometimes work with less.
- Do not let the nest box holes face each other.
- If possible, block the sight between both nest boxes.
- Add a wren guard to your bluebird nest box after the first egg is laid.
- Add a sparrow spooker to the nest box after the first egg is laid.
- Buy time by removing sticks from a nonactive house wren nest (do not remove the whole nest).
Watch the video version
Step 1: Add a second nest box
If you have a house wren on your property that has been getting a little close to your bluebird, tree swallow or chickadee nest box, one of the most immediate things you can do is to add a second nest box.
Don’t get just any nest box. In this case, get another standard bluebird nest box built according to the North American Bluebird Society’s specifications.
The reasons we recommend this type of nest box are:
- Your wren is already interested in this style
- You now have an extra bluebird nest box
- They are more protective of smaller cavity species like chickadees and house wrens
The Woodlink BB3 model box is one of our first best recommendations. It’s a great starter nest box and very affordable, and definitely great for a situation like this. It’s also large enough to install a Blink camera for nest box monitoring and a Van Ert trap.
You can find it on Amazon*.
But we also carry it on our site.
If you’re in a pinch for time, Walmart or the big box hardware stores may have decent options. We don’t usually recommend the Nature’s Way boxes because they’re a little too small and many have a dark top which can turn a nest box into an egg oven. But for house wrens, and with a quick paint job, they’re perfect.
So if you’re in a hurry, this might be a good solution. We strongly recommend buying a water-based white paint to paint the roof a lighter color if you bought a dark top nest box.
Step 2: Optimize the location of each nest box
Once you have your second nest box, it’s time to optimize the location of each one.
If your bluebird has already started building her nest, leave that box alone. Don’t move it until that nesting cycle is complete.
But if she hasn’t, you can move it to a better location. This might also fool the wren into looking at the other, newly provided box.
Before we proceed with how to select locations for each – We do want to caution you about moving nest boxes when you’ve had bluebirds or chickadees routinely use them. There is always a possibility they might not like the new location.
Bluebird Ideal Location: Here are some things to look out for when deciding where to place a bluebird nest box:
- Open areas away from tree lines or thick rows of bushes
- Have perch material like a shepherd’s hook
- One or two small bushes or a tall tree in a generally open area can also appeal to them
Wren Ideal Location: Here are some things to look out for when selecting a spot appealing to house wrens:
- Place your nest box near a thick row of bushes, or a tree line.
- If a tree line is not an option, place your nest box in an area more shaded with some good hiding spots.
- Under a porch or awning might be appealing. Avoid hanging it. Try to still mount the box to a metal pole.
Things to keep in mind:
- Always be sure you’re mounting your nest boxes to a metal pole with at least an 8″x24″ baffle.
- Avoid mounting to fence posts and trees – otherwise you’re turning a nest box into a potential lunch box for predators, which is not good stewardship of these birds.
- Remember, house wrens are native to North America, and therefore we have a duty to protect them as well.
- Once a house wren begins adding material to a secondary nest box, add a 1-1/8 inch hole reducer to the nest box. Protecting the house wren will hopefully keep him distracted with that nest box and less curious about the bluebird nest box.
Step 3: Have an appropriate nest box distance between bluebirds and house wrens
In our experience, placing a secondary nest box at least 30 feet away from an active bluebird nest box is really helpful.
We recommend pairing the concept of distance with the concept of location optimization to really ensure peace.
If you only have about 20 feet of space to work with, it’s still worth trying and can still potentially work out. But you may run into more issues. See some of the other tips to help reduce problems in tight spaces.
As you put these nest boxes any closer together, you might start to run into problems. That’s not to say you don’t try. But we encourage as much space as possible while appealing to the natural preferences of each species.
Step 4: Don’t let bluebird and house wren entry holes face each other
When putting up a secondary nest box, the way the entry holes are oriented can make a difference for bluebirds and house wrens.
If the entry holes are facing each other, you’re giving both birds more visibility which will increase curiosity as well as aggression and anxiety in each.
Step 5: Block the sight between both nest boxes when possible
One way to help maintain backyard peace between bluebirds and house wrens is to try to limit the visibility of each nest box. Having a full bush or tree positioned between both boxes can help reduce curiosity and aggression.
This tip should further allow the house wren to be focused on building his current nest rather than investigating other nest sites for dummy nests.
Step 6: Add a wren guard to your bluebird or chickadee nest box after the first egg is laid
One of the most popular methods for preventing house wren invasions into your bluebird or chickadee nest boxes is to add a wren guard after the residing bird has laid at least one egg.
A wren guard is a little hood or screen that blocks the vision of the nest box entry hole.
We have an article all about wren guards that you might find helpful.
The hope is that other birds that are unfamiliar with that box will not see and be tempted by the nest box because they can’t see the entrance. And if they are, the obstacle of entry will be too difficult for them to care about.
Meanwhile, the residing bird is already familiar with that nest box and knows it has an egg inside. Therefore, it is highly invested in the nest.
We have a video tutorial about how to make a wren guard using cardboard.
A few reasons cardboard is a good idea to use to build a wren guard instead of wood:
- It’s super cheap and easy to produce
- You don’t need any special tools. Just scissors and tape
- You can trim it if you need and customize if you need
- It allows you to train your birds to up to it if you need to.
A downside to using a cardboard wren guard is rain. Eventually it can warp. But it is very simple and cheap to make a second wren guard.
Training bluebirds to use a wren guard (rarely necessary)
We mentioned training your birds to use the wren guard. Sometimes the residing bluebird or chickadee can struggle to get into the nest box once the wren guard is on. In our experience, we’ve found that trimming the front panel so that a little bit of the hole is exposed is helpful.
Then once you see both male and female birds going inside, wait for them to leave, and then reattach the bit that was trimmed off, blocking the whole thing again.
At this point, it might take some time, but they’ll quickly get the hang of it.
Training the residential bird to use a wren guard should only take about an hour.
Sometimes wren guards are less effective
Unfortunately, if a house wren has already been inside the nest box, the wren guard may become less effective. Always always always still put a wren guard up. Just know that wren guards won’t ever fully ensure safety, and its effectiveness does drop if a wren has already been insides.
We’ve also observed wren guards to be less effective during periods of high competition for nest boxes. If the demand for nesting sites is high and availability is low, every bird becomes desperate. Again, we still encourage you to use a wren guard. We just don’t want you to set your expectations as high.
Step 7: Add a sparrow spooker to your bluebird or chickadee nest box after the first egg is laid
A sparrow spooker is an apparatus that is used to hang shiny streamers over the nest box in an effort to scare off house sparrows.
While a sparrow spooker is aimed at frightening off house sparrows, doubling up on deterrents can be really helpful.
You can buy sparrow spookers from sparrowtraps.net and they’re very affordable.
Or you can buy a wooden pasta rack* and make your own. The reason we like this second option is because there are 2 easy ways to mount this to your nest box.
The stem of the sparrow spooker could be taped to the pole or you can attach the base of the rack to the nest box and then untwist and retwist the stem back on.
Another reason we like the pasta rack option is because you can change how many arms are on the rack.
Aside from ordering the pasta rack, you’ll just need streamers. For that, you can use:
- Bird scare tape*
- metallic party streamers*
- shiny gift wrap ribbon*
- cut up a metallic emergency blanket
We have a YouTube videos showing how to make the sparrow spooker.
Step 8: Buying time until the first bluebird egg is laid
You might be wondering how to keep a house wren out of your bluebird, tree swallow or chickadee nest box while the nests are still under construction and there is no egg yet.
If you’ve already followed the previous steps about adding a second nest box and optimizing the location, hopefully the house wren has taken interest in the second nest box.
At this point, check the secondary box. If you see sticks inside, then a house wren has been building in the nest box.
The tip we’re about to present is not one we highly recommend; however, since house wrens are known for building dummy nests, and it is only a violation of the law to interfere with an active nest of a native bird, you can use this option carefully to buy time.
By definition, an active nest is a nest with eggs in it, eggs being laid in it, nestlings inside or the mother bird brooding the nest.
For this tip, all you’ll do is wait until the nest is a little less than half way high (less than half way to the entry hole) and start removing sticks.
DO NOT DESTROY THE NEST. We’re only suggesting you remove some sticks to bring the height down. This will keep the house wren focused on and busy building the current nest that he hopefully won’t take as much interest in the other nest boxes.
Monitor the house wren nest box regularly, and remove sticks as needed.
For safety, wear gloves and always wash your hands afterward.
Once you have the wren guard and sparrow spooker up, because the house wren is a native bird and we must have a heart for conservation, we recommend leaving the house wren nest box alone and letting them finish building and having babies.
Important notes and considerations
This advice will not guarantee peace between bluebirds and house wrens. It can only help manage the situation, but there are no guarantees where wild birds are concerned.
A very seasoned bluebird trail monitor once cautioned many of us in the community about the fact that when we manage nest boxes, we are managing wild animals, and there is only so much within the bounds of our control. Outside of that, they will do what they will do.
An analogy would be to compare us to sheriffs in the wild west. We work to keep the peace among the citizens and protect them. But occasionally fights break out and problems occur.
Sometimes there are bad years as far as house wrens are concerned. We recently heard a report of another house wren invading a house wren nest box and driving out the nestlings. So nothing is ever a guarantee.
Never harm house wrens. House wrens are native birds and as such, they deserve our protection because they have a role in the ecosystem.
Where house sparrows and European Starlings are concerned, we promote trapping and dispatching because they are an invasive species that have devastated the native bird population and are highly ecologically disruptive. But house wrens have an actual ecological niche they play, and we are to respect that.
Your birds will try to defend their nest. This won’t ensure the safety of eggs or nestlings. But if a house wren is caught invading a bluebird’s nest, the bluebird will certainly attack it.
We have caught this on camera, and have been lucky to see that each time, the house wren has escaped unharmed.
So to some extent, you can trust your birds to pick up the slack a little and help out.
While we encourage you to keep going with it, even it if it was a bad year, sometimes the heartbreaks are too powerful. We never want to have bad experiences lead to hate toward a native bird. So if the roughness of nature is more than you can stand, it might be better to take a break from nest box management.
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