Last week in Schenley Park I watched a house wren claiming a nest box at the golf course. While the wren sang near the box, a Carolina chickadee peered out of the hole. One of them was going to win the box. My bet is on the house wren.
Good nest locations are highly contested both within and between species. Chickadees, house wrens, bluebirds, tree swallows and house sparrows all compete for the same nest boxes. The winners are determined by timing, temperament, and weaponry.
Chickadees are brave but small. They usually lose.
Eastern bluebirds and tree swallows are well matched and can share the same territory if two nest boxes are placed next to each other. The bluebirds begin nesting earlier and pick a box. The swallows arrive later and pick the other. But it can go either way.
House wrens don’t need to nest in boxes but when they’ve picked one they are persistent, quick builders and will remove the eggs and very young nestlings of other birds. They trump the other three.
By law you can’t interfere with these native species but you can put up more boxes. The wider the selection, the less they’ll compete.
House sparrows are another story, though.
Aggressive and well armed, house sparrows always win. They claim several boxes even though they use just one. They kill the nestlings and even the adult bluebirds incubating eggs. The only way to protect bluebirds is to trap and kill the house sparrows. You can to do this because house sparrows aren’t protected by law. They’re “listed” as an invasive species. (Click here to read more at the bluebird website, sialis.org.)
In the city there’s cruel justice for house sparrows. When another invasive species wants their nest they’re out of luck. The starlings win.
(photos by Cris Hamilton, Chuck Tague, Marcy Cunkelman and Robert Greene, Jr.)
my bluebirds always arrive first, as you said. But then the house sparrows kick them out. The only thing for me to do is let the sparrows build their nest, lay their eggs, then I take out & dispose of the eggs. The sparrows must think — all this work for naught, and then they give up — til next year. Then the bluebirds can have their turn — I usually get a successful nest & some eggs that hatch. The sparrows have gone elsewhere. It’s never as good as the first nesting, for some reason. When people hear that I’ve disposed of the sparrow eggs, they go “aw-w-w.” And I tell them, if you’ve had a sparrow kill your mother bluebird — I find her all pecked to death — your fury would be so great, you’d have no trouble getting rid of the sparrow eggs.
Mama bluebird has been so busy all week long, laying one egg every day for 4 days. I went out this evening to give her and dad more meal worms and check for egg number 5 and lo and behold all 4 eggs were on the ground below the box, cracked and eaten! So sad for them. Do you think it’s a house wren or house sparrow? Do you think mam and dad bluebird will lay more eggs since it’s only April 12th?
Diane, I don’t know what species did it, but you can get good answers & advice from the North American Bluebird Society at http://www.nabluebirdsociety.org/ They even have a Hotline contact for all your questions (see their home page).
Hi Libby, I too feed the wildlife outside and I put up many different boxes of all sizes so many birds could choose their nest boxes. If that happens to you again with the eggs and The sparrows fighting for the nest boxes, instead of destroying the eggs, if you have a wildlife rehabilitator around in your area, you can give them the eggs and they will incubate them and have surrogate sparrows that cannot go back into the wild raised them. Just another alternative instead of destroying the eggs, every thing has a right to live and yes it is sad seeing your female bluebird pecked to death on the floor, but that doesn’t mean, genocide for the rest of the Sparrow species in your yard. If you put in your computer wildlife rehabilitators in your area, I’m sure you can work something out with them and you could give them the eggs for them to raise, if the problem keeps happening to you. Best regards and thank you for taking care of our wildlife animal cousins in the the yard. Best Regards. – Pete.
Peter, Taking the house sparrow eggs will cause the female house sparrow to reclutch up to 8 times to replace the eggs that were lost. Meanwhile the male house sparrow will continue to claim the territory & kill bluebirds. The only thing that keeps bluebirds alive is to eliminate the male house sparrows.
Since 2012, we’ve had 3 Bluebird boxes on our property. The first year, we had 2 successful clutches hatch and fledge from one box. In 2013, the first clutch hatched in that same nest box then died from the cold, the 2nd clutch was successful. Last year, the trouble began with the House Sparrows. They killed the babies of the first clutch and broke the eggs of the 2nd. For the rest of the summer, we pulled out a total of 17 House Sparrow nests from the 3 boxes and never saw the Bluebirds for the rest of the summer. This year, we started with a Bluebird pair claiming a box. A few days later, Tree Swallows were seen dive-bombing the Bluebirds relentlessly..the Bluebirds left. The Tree Swallows were seen flying all around the box for a couple days, perching several times on it and then they disappeared. We found a dead Swallow at the base of the box a couple days after noting the disappearance of them. It’s been 2 weeks now and not a bird, not even House Sparrows, has built a nest in any of our boxes. The whole situation is odd.
Do bluebirds even try living inside the (Pittsburgh) city limits? I’ve never seen one here, but my observations are hardly comprehensive.
Sara, there are nest boxes at Schenley golf course (and probably other city parks/cemeteries) where I have seen bluebirds. But there is so little bluebird habitat and the competition is so keen that they are very unusual and might not be successful.