We have been having a difficult time with two of our nest boxes. The only birds that have been using them are House Sparrows. We check them often and remove any nest material from the invasive species, but these birds are persistent. So we have decided to remove the boxes altogether. Sorry sparrows, you will have to find somewhere else to nest.
Monitoring nest boxes can have its vicissitudes. Invasive birds can hamper your success and you must deal with them in an expeditious manner. Many times, we can place a guard around the nest box opening, reposition the box, or even change the style of box. Sometimes you just have to cut your losses and take the whole thing down for the season.
We hope that we can replace the boxes next year for better results. That will entail some monitoring of the area before placement to make sure the local birdlife is what we want to attract. In the meantime, you will notice our data graphics have changed on those boxes. We still have thirteen active boxes, so keep checking back for how we are doing.