Just the mention of house sparrows will make many bluebird lovers recoil. This highly aggressive species, which was imported from Europe in 1850, is responsible for the death of thousands of bluebirds every year. House sparrows not only occupy empty bluebird nesting boxes, but they also storm occupied boxes, killing adult bluebirds and nestlings. There are currently no bluebird nest box designs that completely repel house sparrows, but there are a number of passive and aggressive measures you can take to reduce their population.
Passive methods to control house sparrows
The most obvious and important strategy for dissuading house sparrows from hanging around your yard is to never feed them. In addition, make sure you set up your bluebird houses as far away as possible from houses, sheds or other structures, which house sparrows frequent. During the winter, check your nest boxes and make sure that house sparrows aren't roosting there. If they are, you should not only expel them, but also move the nesting box to a different location.
What to do once a house sparrow has built a nest
Its is generally agreed upon that removing a house sparrow nest is the best course of action. However, beware of the fact that removing a nest will often agitate the male house sparrow, sometimes causing it to invade any bluebird nest it can find and go on a killing rampage.
For this reason, the 'decoy box' method is also effective. Instead of removing the nest, simply remove the eggs and freeze them for a few hours, killing the embryo. Then replace them, placating the adult house sparrows. This way you'll prevent the multiplication of the house sparrow breed without putting your bluebirds in jeopardy.
House sparrow traps
There are a number of house sparrow traps that can be used. Some house sparrow traps are designed to sit inside the nesting box and trap the house sparrow as it enters. These traps must be monitored consistently, as they can also trap other birds as well. When you find a trapped house sparrow, you have a number of options in terms of what to do with it.
Since house sparrows are an invasive species, they aren't protected by wildlife laws and it is legal to kill them. If you catch a house sparrow in a trap, you can place a plastic bag over the trap and the bird will fly into it. Then, press on its breast bone and crush its lungs, which will kill it instanteously.
The other option is to clips its wings. If it is unable to fly it will be eaten by predators very soon. If you find these options to be inhumane, you can release them into the wild, though it is discouraged. If you end up doing so, release the birds in a very urban area, where they are unlikely to make it back to prey on other birds.
Other house sparrow traps work by luring the sparrows into cages with bait. Lastly, it has been found that hanging monofilament fishing line around a nest box often repels house sparrows, or at least delays their occupation.
The bottom line on house sparrows
House sparrows are a truly unfortunate pest and one of the most difficult things that bluebird lovers have to deal with. It's important to be patient and explore all your options, as house sparrows are a tenacious species capable of destroying your birding experience.
Ready to purchase a bluebird nesting box? Check out our bluebird house collection Want to learn more about bluebirds? Check out the other articles below.
Ready to purchase a bluebird nesting box? Check out our bluebird house collection. Want to learn more about bluebirds? Check out the other articles below.