Thank you. I just wanted to make sure the slits were not something we needed to put in. When we make nesting boxes for the birds, they recommend roughing up the wood under the hole on the inside to make it easier for the birds to cling.
This really does sound like an interesting project and we have plenty of scraps that can work. We have a lot of fun observing the birds at their houses during breeding season and have learned so much about their behaviour. Sure we see insects on the flowers, but it would be so neat to see their lives away from there. We have seen digger wasps build their "nests" and that was fun.
