Bluebird Box?

By Rey Wells

This is year three for the “Bluebird” box in our side yard in northeastern New York State.  Two years ago, Tree Swallows arrived early and raised a brood.  I then cleaned out the box, hoping that bluebirds would move in.  Instead, a pair of House Wrens claimed it and successfully raised chicks.

Last year House Sparrows arrived early and claimed it.  They successfully raised chicks.  I intended to clean out the box once their young had fledged.  But before I got to do that, a pair of bluebirds moved in and built right on top of the sparrow nest.  They had success, also.

On April 16th of this year a pair of Black-capped Chickadees inspected the box but moved on.  It was pretty early in the season.  On April 27th a pair of House Wrens arrived and started to fill the box with sticks.  Here is one of the wrens doing just that. (1)

In early May trouble arrived.  It was a pair of House Sparrows.  The larger birds moved right in and took control of the box.  Here is one of the wrens appearing helpless as it perches on a twig and exchanges stares with the male sparrow in the box opening. (2)

But the wrens didn’t give up.  They chattered continually close by, and the male sang often.  Then one of the wrens (I’d like to think the male) went on the attack.  Here he (or she) is dive bombing the male sparrow as the female sparrow looks out of the box opening. (3)

After a few days of continual harassment by the wrens, the sparrows had enough.  They moved on.  It was back to normal breeding activity for the wrens.  Here is one of them leaving the box for another stick or two. (4)

The wrens took back control of the box on about May 7th.  Fast forward to June 24th.  The chicks are about to fledge.  Here is one of the parents about to feed a chick at 12:06 PM. (5)

Starting at about 12:40 PM, one by one, nestlings become fledglings.  Here is a photo taken at 12:56 PM.  It is the third nestling that I watched come to the opening.  Note that its feet are gripping the outside of the hole.  Less than two seconds after each one progressed to that position, it flew away.  (6)

I have theorized that songbird parents might not feed chicks on fledge day to encourage them to leave the nest.  Obviously, that is not the case with House Wrens.  If anyone knows it to be the case with some birds, I’d like to know.

For a day or so, there was wren activity in the hedge row as the parents continued to tend to the fledglings.  Then there was silence as they had all moved away.  I cleaned out the box, hoping once again for bluebirds.  But about a week later, adult wrens moved in to start the process all over again.  As I write this on July 14th, a female is once again incubating eggs.

House Wrens are fierce competitors for nesting spaces.  Given that and the fact that they often have two broods, they exist in large numbers.  Their population is estimated to be close to 200 million.  They are the most widely distributed birds in the Americas.

House Wrens building a nest (1)
Start of the standoff (2)
The wren is smaller but mightier (3)
The nest building continues. (4)
Feeding time (5)
Time to grow up. (6)