This is a box that looks like a bird house nest box . so very discreet , it can trap invasive English House Sparrows. The trap does not kill . so if you get a good bird in the trap then just let it go . English House sparrows kill other good bird to expand and take over more nesting boxes . if you are not wanting to trap then use the 7/8 oval for Violet Green swallows , see the you tube video (bird house oval entrance hole for Violet Green swallows) or the you tube video (small bird house entrance hole size) email protectswallows@shaw.ca