Hi, I'm a Brit from Northumberland going through a manic nestbox building phase and have stuck countless tit boxes with 25, 28 and 32 diameter holes as well as a few tawny owl boxes. I have two acres with a boundary of mature(ish) trees and a small stream running along the bottom. Does anyone have any notion of other boxes I could make for different species (asides from wrens, robins, blackbirds, sparrows) which are likely to use them? I heard that tree-creepers are very infrequent box users and we don't get woodpeckers or nuthatches. Any tips or design ideas would be greatly appreciated, thanks guys.