Bird House Additions – Bluebird and Wren Nest Boxes

This week’s projects were to add two bird houses to the yard – a Bluebird nest box in the garden and a wren nest box to be attached to one of the River Birch trees.

A few years back, I had put up a Bluebird house in early Spring, but it was soon taken over by House Sparrows. I then read information from the PA Bluebird Society (after the house was up), that House Sparrows are aggressive and often kill Bluebirds if they are in a house that the Sparrows want. This occurs in areas that are frequently visited by Sparrows, such was and is the case with our location. Needless to say, I removed the house before the Sparrows could set up a nest and breed more Sparrows.

I had given up on the idea until I decided to try again using this house I had purchased, but using the modifications that Bluebird-support organizations suggest.

The first modification is the use of monofilament line, or fishing line, fixed to the front of the box and running down each side of the entrance. With a front opening door, the line was a bit wider than I wanted, but hopefully it will have the same effect (it reportedly scares off House Sparrows who cannot see the line).

I also added a entrance guard from Kettle Moraine Woodworking. The opening is 1 1/2 inch in diameter. The diameter is critical.

The other suggestion from Bluebird Conservation was to add a skylight – a hole in the roof covered with plexiglass. Evidently, House Sparrows like to next in a dark space while the Bluebirds to not care….or care as much…or perhaps even like it.

The house went in this second week of March. The ground was not frozen at this point, so the support was easy to get erected.

Modified Bluebird Nest Box with monofilament line and skylight.

Having some extra cedar, I built a nest box that hopefully will be suitable for Wrens. The diameter of the entrance is 1 1/4 inches. I attached this to one of the River Birch trees on the upper side of the yard. Plastic zip ties straps were used to attach the box to the tree. The house was designed to have one side of the roof open to enable cleaning.

The location in the River Birch is not as isolated as it probably should be in that it is close to the street and sidewalk. It will be better once the leaves on the tree emerge.

I might have missed the timing window for Bluebirds nesting for this year. The timing for wren nesting is coming up however.