They are normally fastened to a tree (high up!). Our lad PhantomVeg is a licensed bat handler (no, it's not rude!) and has put them up in various places. They have a ridged bit below for the bats to cling to, and just a slit as an entrance, but otherwise look a bit like a bird box.

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Some days you're the statue, some days you're the pigeon!

vegheaven.blogspot.com Updated Aug 6th 2008