House Sparrows are a constant nuisance to both bluebirds and bluebird landlords. Sparrows compete heavily with bluebirds for nest boxes and they can do deadly damage to adult bluebirds and their young. The best way to deter house sparrows is by using tried and true methods that other bluebird landlords have had success with. In this article, I’ll show you how to deter house sparrows with fishing line.
This method was originally made popular by Joan Watroba, editor of the Bluebird Society of Pennsylvania newsletter (source). Since this method has proven to be so effective, I wanted to provide you with a complete illustrated guide for using this method, showing you step-by-step how to deter House Sparrows with fishing line.
I’ll tell you why this method is effective at deterring House Sparrows, the materials you’ll need for this project, and the steps you’ll need to take to make this method work for you. Let’s get started.
Pro Tip: To see my favorite bluebird nest box that I use and recommend, check it out on Amazon here.
Why Monofilament Fishing Line Deters House Sparrows
Hanging a few feet of monofilament fishing line around a bluebird house’s entrance hole may spook House Sparrows due to their poor eyesight, which, ideally, will be enough to keep them from using the nest box.
Bluebirds, and other native cavity nesting birds, are typically insect-eaters with good eyesight. House Sparrows, on the other hand, mainly eat seeds, so their eyesight does not need to be as sharp. As such, when sparrows attempt to enter a nest box with fishing line hanging from it, it usually spooks them and they become hesitant to use that particular nest box.
According to Joan Watroba, even sparrows that made an initial nest in a nest box fitted with fishing line were deterred from making second and third nesting attempts once their first nest was removed (source). So, even though this method, like all methods, isn’t 100% effective at deterring House Sparrows, it does seem to be very effective compared to other deterrent measures.
So, if you’re ready to give this a try, let’s look at a few materials you will need in order to install fishing line on your own bluebird house.
Materials Needed
- 4 Pushpins or Metal Screws
- Monofilament Fishing Line (6 lb. test clear or lightly-tinted) – here’s a link to this fishing line on Amazon
- Bluebird Nest Box (Standard wooden bluebird house, not a PVC pipe nest box)
You can choose to use either pushpins or metal screws for this project. Screws will be sturdier, but they will also leave holes in your nest box if you take them out, which some people don’t prefer. I choose to use small pushpins or thumbtacks, because they are easiest to install and they don’t leave holes in the bluebird house.
This method will work for almost any wooden bluebird house. However, since you will be installing fishing line to the front of your nest box, this method is more convenient if you have a side-opening nest box, so that you won’t have to worry about disturbing the monofilament when you open the box. Check out my favorite side-opening nest box (the one that I use) on my Recommended Tools page here.
Instructions: How to Deter House Sparrows from Your Bluebird Nest Box with Monofilament Fishing Line
1. Press two pushpins securely into the front of the nest box roof (about 1 3/4″ apart).
The idea is to place the pins or screws about 1 3/4″ apart on the front of the nest box roof, on either side of the entrance hole. The round entrance hole should either be 1 1/2″ in diameter for Eastern Bluebirds or 1 9/16″ in diameter for Western and Mountain Bluebirds, so spacing the pins apart 1 3/4″ will make them just a little bit wider than the entrance to the nest box.
2. Press two more pushpins into the bottom of the front of the nest box (about 1 3/4″ apart).
Now, press the other two pins into the bottom front of the nest box, in line with the pins at the top. You can press these bottom pins into the front panel of the nest box, or into the floor board, depending on the style of bluebird house you are using.
3. Tie the fishing line to the top left pushpin.
Once the pushpins are in place, you can begin tying on the fishing line. Start by securely tying the fishing line to the top left pushpin.
4. Wind the fishing line around the bottom left pin
Next, wind the fishing line a few times around the bottom left push pin, making sure the line is tight.
5. Wind the fishing line around the bottom right pin
Then, pull the line tight and wind it a few times around the bottom right push pin.
6. Pull the line tight and fasten the fishing line around the top right pushpin
Finally, pull the line tight, wind it a few times around the top right pushpin, and tie it securely so that all of the fishing line stays in place.
Now the monofilament fishing line should be surrounding the area around the entrance hole to the nest box. When sparrows attempt to enter the nest box, they should be spooked and fly away. Ideally, this will be enough of a deterrent to keep House Sparrows from nesting in your bluebird house.
Of course, no method is 100% sparrow-resistant, so make sure you read the article I wrote called How to Keep House Sparrows Out of Bluebird Houses for more best practices when dealing with this invasive species (click here).
If you want to attract bluebirds to your yard THIS YEAR, the best place to start is the Bluebird Landlord Audio Guide. In this audio guide, I’ll tell you everything you need to know about attracting bluebirds in just 59 minutes and 38 seconds.
Check out the Bluebird Landlord Audio Guide here.
Things to Keep in Mind (Maintenance)
Check the tightness of the fishing line when you monitor your nest box
As a responsible bluebird landlord, you are probably monitoring your bluebird houses at least weekly. Make sure to check your fishing line-fitted nest boxes at least once a week to catch any issues that might arise.
First, check to see if any lines are becoming loose. This probably means you just need to retie the fishing line to the pushpins to make the line tight once again.
Next, check if any pushpins have fallen out. If your pushpins are frequently falling off, consider replacing them with sturdier metal screws.
Replace the monofilament fishing line when it becomes weak
It would be rare, but it is possible that your fishing line might become weak or completely break during the season. If this happens, just replace the whole line with a new one. Fishing line is relatively cheap – less than $10 for 300 yards here on Amazon – so go ahead and fully replace any weak or broken lines.
Remove the fishing line at the end of the nesting season
At the end of the nesting season, in late August or early September, take the monofilament fishing line off your nest boxes. During the winter, birds will use your nest boxes for roosting instead of nesting, so you won’t need to deter House Sparrows at this time anyway.
I recommend having your bluebird houses up and ready to go for bluebirds by mid February, since this is when they’ll start scouting out new nesting locations. So you can put the fishing line back on your nest boxes around February 15th to keep the sparrows away.
Conclusion
Thanks for reading this article about how to deter House Sparrows from using your bluebird house with monofilament fishing line. Even though House Sparrows can be a huge nuisance to bluebird landlords, thankfully, there are methods like this one that have been proven to be very effective at keeping sparrows away. Give this method a try!
If you want to learn some other best practices for dealing with House Sparrows, check out the following articles I wrote on this topic:
- How to Keep House Sparrows Out of Bluebird Houses (click here to read)
- How to Get Rid of House Sparrows (click here to read)
