Hi Stephen and welcome.
Have you made any birds yet? That's a great idea to place them around the school.......
Maybe also consider rewarding the children with fact sheets or something similar.
Some of Johan's birds also have interesting stories or backgrounds to them that may well appeal to children if retold appropriately.
For example, there is a story about how the Hoopoe got its crown on the build thread I did here (last page)......
Hoopoe - Johan Scherft