I’ve had huge successes the past couple of years with my garden Tree Sparrows, but this year, I fear that they might not be doing quite as well. I admit I’m yet to open the boxes, but the lack of activity around all three boxes suggests that for some reason the broods have all failed.
There are a variety of reasons why birds fail to breed successfully, even in sites and boxes like mine that have produced several broods of young in previous years. It’s sad when it happens, but in most instances it’s a natural event and just has to be accepted. Last year my three boxes produced close to 30 young Tree Sparrows, hopefully that’s enough to compensate for the losses this year and it’s not too late for a second breeding attempt.
When I open the boxes, I’ll probably have a better idea of the cause of failure. Of course I could have added a camera to keep an eye on them and watch them develop – perhaps I’ll do that next year! This did get me thinking about the cause of nest box failures though, some of which I have shared below.
Weather plays a huge part in the success or failure of most breeding birds. A late cold spell can chill eggs and heavy rain over several days can have exactly the same effect. Even in the best made nest boxes water can find its way into the box and cause eggs or very young birds to become chilled. Perhaps a wet period this Spring did this for the Tree Sparrows in my garden.
There isn’t much you can do about the weather, but you can position your nest boxes away from the prevailing wind direction so that the rain isn’t driven in. Shelter them a little by siting the box on a tree or wall where possible.