These photos with accompanying text highlight my evolving attempts to make nest boxes House Sparrow resistant. Until the 2009 nesting season I had not discovered House Sparrows nesting in any of my mono-line treated boxes. This year, 2009, I had two instances of House Sparrows nesting in boxes having my mono-line 3 treatment proving that the treatment does not make a box House Sparrow proof.

These two boxes and others are hung in trees in a memorial park in Los Gatos, California. The first photo below includes a third nest box (in the left of the photo) from which four Western Bluebirds fledged. This third box initially did not have my mono-line 3 treatment, but it was added once the Western Bluebird nest was discovered.

House Sparrows nest under the tiles in the arch on the right of the photo. In fact, several sparrows can be seen in the photo on the top of the tiles. During the 2008 season there were many sparrow nests being built under the tiles, so I brought the problem to the attention of the park's maintenance staff. They filled many of the holes under the tiles with an expanding insulating foam which prevented most sparrow nesting activities. Unfortunately, there are several broken tiles which allow entry, and, therefoe, nesting.

So here we have Western Bluebirds and House Sparrows nesting in close proximity to each other. Most importantly, the bluebirds fledged. Did the mono-line treatment help? I want to believe so.

Since discovering the House Sparrow nests in my treated boxes, I've taken two actions:

1. Adjusted the standoffs to decrease the distance between the vertical mono-line segments. Continue to reduce this distance if necessary.
2. Tipped the box forward by reforming the hanger wire. This action slopes the front of the box in a slight downward direction similar to that of a Peterson Nest Box. Continue to increase the slope if necessary.

One point that I want to stress is to always keep the mono-line taunt by adusting the standoffs.

So the quest to make nest boxes House Sparrow proof continues realizing that one may have to settle for resistant.