While investigating monofilament, you might be wondering how to put it on your nest box, how exactly does it need to go on my nest box in order to deter house sparrows? When installing monofilament line on your birdhouse, the most important thing is to place to vertical strings running down the front of your box just ⅛ of an inch from either side of the entrance hole.
Before we get started, we just want to clarify that monofilament line is fishing line. You can find it pretty much anywhere, including Walmart. Just be sure you buy 6# (pound) line that says monofilament on it. It is our experience that a thicker line will also deter birds you were hoping to attract to your nest box.
Installing the monofilament line is extremely easy, and all you’ll need for supplies are:
- A ruler or tape measure
- 6 # monofilament line (no more, no less)
- Thumbtack, nails, screws or screw eyes
- Scissors
- Pencil or other marking tool
- If using screws – you’ll need a screwdriver, and having an awl is helpful
- If using nails, you’ll need a hammer
Step 1: Measure ⅛ of an inch from the entry hole and mark
The first step to installing monofilament is to get everything marked up. Right now, we’ll focus on the entry hole. You want to install your monofilament line ⅛ of an inch from the entry hole on either side. To do this, get out your tape measure or rule, make sure you’re measuring from the center of the hole, and mark a spot ⅛ of an inch from the hole. Do this on both sides.
Step 2: Mark your lower sections
Now, align your measuring tape or ruler vertically, and measure about 7 inches down (if this is a standard approved box). Mark that spot making sure it lines up with the markings you made by the hole. This ensures that when you tie the line, it will remain ⅛ of an inch from the entry hole.
Mark those two spots.
Step 3: Mark your upper sections
In the same way you aligned your measuring tool from the markings near the entry hole, to the bottom section of the box, you’ll do this for the upper section. Because most boxes are hooded, this will be a bit tricky. Therefore, mark your spot and then unwind some monofilament string. Run it from that marked spot at the top to the spot at the bottom. Look at how the line runs. Is it still ⅛ of an inch from the entry hole? Does it appear too close? Too far?
Adjust your markings as needed.
Step 4: Get your starter holes going and then drive in your nails or screws (unless you’re using thumbtacks)
An awl is just a really inexpensive go-to tool. Have it handy to make the process easy by poking into your markings to get a small starter going.
If you are using thumbtacks, even easier. Go ahead and push in your thumbtacks into each starter hole.
If you are using a nail, hammer them in. If a screw, drive them in. If a screw eye, start twisting. Then, what makes it easier is to stick the awl through the hole of the screw eye, and use it as a lever to quickly twist it in.
A note of caution: don’t drive your screws or nails too far to where the points are exposed inside the box. You don’t want to cause unintentional harm to the mother bird or nestlings inside. So make sure when you do this, the tips of the screws, nails or anything you’re using aren’t showing up on the other side to where they could stick them. If you drive your screw too far, just unscrew until it’s no longer exposed. Don’t worry if they stick up pretty high on the outside. That’s just fine.
Step 5: String the front of your nest box
Now you’re ready to string the front of your box. This step isn’t terribly difficult, but it can be frustrating because monofilament likes to bounce back to its original curve.
Start on either side of the box, tie off an end. Make sure to knot it good. It might help to even wrap it around that first screw a few times and then tie. Now run it down to the bottom, keeping the line tight. Before tying it off and cutting, wind some line around this screw as well. Tie it off, and cut your line.
Cut off any excess and dispose of it.
Continue this step for the other side of the hole.
Installing monofilament on the top of your nest box
For some, after this step, they’re done. But others like to be extra careful. Some suggest adding monofilament to the top of the box to discourage house sparrows from singing on top of the box. If they can’t sing, they aren’t as easily able to claim the box.
Keep in mind, house sparrows and eurasian tree sparrows are very persistent, and this is only a tactic for discouragement.
The way we suggest stringing the top is forming a pattern in which an X is enclosed in a square.
Stringing the top of the box is a lot easier because it doesn’t require any measuring.
Step 1: Mark your sections
Marking your sections will depend on the style of box. If the backing that the box is mounted to (back wall basically) rises above the roof line, mark your first 2 holes on that (as pictured).
If the back wall is the same height, then mark your first 2 holes at the back end of the roof.
You don’t even need a pencil for this. You can go straight to using your awl. And if you are using thumbtacks, you can just drive them straight in.
After your backs are marked, go ahead and mark the front of the roof.
When marking the front of your roof, make sure the area in which your nail, or screw will not come into conflict with other screws.
Step 2: Hammer in your nails or drive in your screws
Just as you did for the vertical installation at the front of your box, you’re going to hammer in your nails or drive in yoru screws, or push in your thumbtacks.
A word of caution: when driving nails into the roof, don’t make them go too far down to where their points are exposed inside the box. You don’t want to unintentionally cause harm to the birds.
Step 3: String the top of your box
After having vertically strung the front of your box, you should be a pro at this step. Just tie off a section of monofilament onto one of your roofing screws and start running the line around. You’ll form a square at first. Then run it in a criss-cross pattern until you form an X.
Once you’ve made your pattern, tie it off and there you go.
For gabled roofs, you can form an X on both sides of the gable panels. It’s also not a bad idea to run line at the top where the two sides meet. This further discourages sparrows from singing at the top.
You can get more creative running monofilament on the sides of your box as well.
One thing to be very cautious about is having loose line hanging from your box, or any slack. Keep everything tight. Some guides out there suggest having loose monofilament hanging down on your box too – using nuts to weight it downward so it doesn’t curl and flutter around.
However, this could pose significant danger to your birds. They can easily get caught up in loose string. The last thing you want is a bird with a broken wing. So again, nothing loose, nothing hanging. Keep everything tight around your box.
Of course, you’re probably wondering if this works. You can find out more about the effectiveness of monofilament as a sparrow deterrent here. In this article, this deterrent technique is tested in multiple boxes. Some having monofilament attached to both the top and running down the front, while others only had the front of the box done.
