Bluebirds disappear in favour of sparrows when housing densities reach two per acre, the mean housing density in Bermuda today. The House Sparrow nests from February to June. A sparrow nest is an untidy nest made of grass, and trash often wrapping over the top of the nest.
The Bermuda’s bluebirds in the past used to have 3 broods a season but because of the aggressive house sparrow competing for nesting boxes it has almost been reduced to one brood in June and July.
Sparrows fit through the same size hole (1 ½ inches) as the bluebird, and as such they often evict bluebirds from nesting boxes killing the young and adult in the process. Many bluebirds are attacked and killed by groups of sparrows. When sparrows occupy your bluebird box, the male sparrow has staked his territory, claimed your nesting box for the season and will continually attract females to his box.
The only way to rid the nesting box of sparrows is to deter the male sparrow from nesting. There are various ways to do this:
- Continually remove the sparrow nest, or wait and remove the eggs and nest.
- Leave the box door open for a week or more.
- Take your box down for a few weeks.
- Trap and cull the male sparrow.
- If one continually evicts the sparrow and there are bluebirds in your area the bluebird will nest.
Discourage House Sparrows by adding a skylight by Dean Rust
Here is an easy method to discourage house sparrows from invading and “taking over” your bluebird nest box ………….ADD A SKYLIGHT !!
House sparrows are and have been the bluebirds’ #1 Enemy; so let’s get started on “how to” prevent them from driving your bluebirds away.
If you have an old nest box or a new one, this technique will work. You will need:
- 1/4” power drill
- 3″ hole saw
- 4” x 4” plexiglass piece (1/4” works great)
- 4 copper screw nails/brads for plexiglass
- tube of silicone caulk for plexiglass
- 1/16” drill bit for brads; 1/8” drill for screws
- tape measure & straight edge
- hammer for plexiglass
- Locate the center point on the roof of your box directly over the floor area.
- Puncture the spot with a nail; then drill a 3” hole completely through the top.
- Pre-drill the holes 1.5“ from the corners in the plexiglass
- Position your plexiglass or over the opening and hammer a copper brad into each hole
- Place a bead of silicone caulk to seal the plexiglass on all 4 sides.
Congratulations !! You are finished and can install your bluebird box to its desired location.
I have used this “Bluebird Box Skylight” technique on many sparrow-infested trails with great success. Nothing is 100% effective (“Sparrow-proof”) when trying to discourage house sparrows but I think you will be happy with your results. It is worth a try just 15 minutes of your time and a couple dollars in cost.
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