Bats benefit farmers by eating many insect pests, but bat populations are decreasing due to habitat loss. Farmers can help bats by providing bat houses, which also helps the farmers by reducing pests. However, more research is needed to confirm how much bats help with pest control in agriculture. For this 2001 study, ten organic farms in central California were chosen to have bat houses installed as part of a pest management project. A total of 45 bat houses (25 on buildings, 20 on poles) were put up in June and August 2001 to test what designs and locations bats prefer.

Bat houses at five of the 10 farms (50%) were used by bats within one to five months, which was encouraging because the houses were installed late in the year, after bat colonies had already formed. Eleven of the 45 houses (24%) were known to be occupied, though possibly more were used. Bat houses on barns were used more than those on poles (36% vs. 10%), but more monitoring is needed over two summer seasons to know bat preferences. This study is the first part of a longer project. The next step (Phase II) will measure how much bats reduce crop pests once enough houses attract bat colonies.