House Sparrows are a threat to many cavity-nesting native birds in North America (and in many other parts of the world). They were introduced from Europe and are now often a pest species and not covered by any wildlife protection laws in Canada or the U.S., except for anti-cruelty laws. House Sparrows will often attack and kill native species in order to take over their nest cavities or nest boxes. I experienced this first-hand when a pair of House Sparrows decided to take over a nest box on our car-port where a pair of Violet-green Swallows was raising three chicks. The sparrows killed the female swallow, and since the surviving male parent seemed incapable of feeding the chicks, I ended up raising them in our house and eventually saw them successfully fledge.
That incident is what prompted me to investigate ways to trap House Sparrows in nest boxes meant for swallows or other native nest-box users. There are several commercial traps one can buy but they are expensive and unnecessarily complex. Here are instructions to make a simple, cheap and effective sparrow trap. Most people will have the necessary materials already at hand. This is meant for a nest box with a circular hole (not a large rectangular opening like some bluebird boxes).
Materials:
- A small piece of 1/4 inch plywood or something similar (like particle-board in the photo)
- a 1-inch nail (I trim off the sharp end)
- some strong thread (I use dental floss)
- a thumb tack
- A half-inch screw with a flat head (see photo)
Materials needed to make the trap.
1. Cut the plywood into a shape that will cover the nest box hole when it swings down but allows the hole to be open when set (see the photos below). Let’s call this the trap-door. Drill a screw hole in the trap door large enough to allow it to swing freely but still remain close to the nest box.
2. Mount the trap door above the nest box hole so that it completely covers the hole when down but doesn’t obstruct the hole when set. Drill a hole in the nest box for the nail to hold up the trap door when set (see arrow in photo); the hole should be wide enough to allow the nail to easily slip in and out but still support the trap door.
The sparrow trap set (left photo) and sprung (right). The arrow indicates the nail holding up the trap door when set.
3. Connect the thread to the nail at one end and to the thumb tack at the other end, with enough thread to loop across the entrance hole so that a bird coming through the hole will hit the thread and pull out the nail. You will likely have to adjust the length of the thread to get it just right.
Inside the nest box. The thumb tack holds one end of the thread securely. The nail fits into the hole but is pulled out when the bird hits the thread, releasing the trap door.
4. To set the trap – swing the trap door up. From inside the box insert the nail through the hole so that it supports the trap door.
So now you’ve trapped that murderous House Sparrow. How to get it out of the box. Hold a net or bag over the nest-box hole and while keeping it there slide up the trap door. The sparrow should fly out into your net. I use an old pillow-slip with a wire loop stapled to hold it open (see photo). The sparrow is more likely to come out if I hold up the other end of the pillow-slip so that it appears to be an escape route. Be vigilant – House Sparrows can escape through tiny openings.
Old pillow slip with a wire loop stapled to hold it open when positioned over the nest-box hole.
You can then dispatch the House Sparrow in a humane way. If you accidentally catch a swallow or other legitimate cavity-nester you can release it immediately un-harmed. Once the trap is set be sure to check it regularly.
One other thing – please encourage your friends and neighbours not to allow House Sparrows to nest in their nest boxes.
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