Within days of writing my previous post I'm pleased to report that four of the petrel boxes show some sign of use! How do I know the box has been used? The two images below show the differences between an unused box (note the undisturbed soil) and one which a petrel has explored - the soil lining the box has been scraped from the centre of the box and pushed up into the corners, the bird has brought vegetation inside, there is a small brown feather and an unmistakable musty smell which can only belong to a petrel. Both boxes are in the same cleit with a pipe burrow facing in the same direction so it's unlikely that vegetation would have been blown by the wind into one and not the other.
It looks like our old birds are back in the 'same' sites, which would suggest the new design is acceptable as a nest site. Of course I'm jumping the gun a little as the birds are yet to nest and maybe they will decide the box is not quite the luxury summer home they wanted. The other box is one to keep an eye on as in the past birds did show an interest in a box inside the same cleit but never settled to breed. There's still time for birds to occupy other boxes and plenty of time for young birds to 'play house' which basically means they are too young to breed this season but that they test out potential sites for future years. We would of course be delighted if many more boxes were used this year but will be pleased if any birds nest and then successfully fledge their young.