September 2005, Volume 3, Issue 9

Concrete Trees


Bat Conservation International’s Bat House Project has moved aggressively in new directions to increase the number of bat species that can find homes in artificial roosts.

Since its creation in 1993, the program has collected and analyzed data from 7,000 bat-house enthusiasts around the United States, Canada and other countries. Those observations by volunteer Research Associates dramatically improved bat-house success and amply demonstrated the value of bat houses in providing refuge for bat faced with habitat loss.

But traditional bat houses are most useful for about 14 species of bats – such as little brown myotis, big brown bats and the endangered Indiana myotis – that roost in crevices.

Now BCI and its partners are also developing new types of alternative roosts to meet the needs of forest bats that have been displaced by the loss of old-growth trees that offer such bat-friendly features as extra-large hollows.

Eighteen artificial tree roosts, made originally with concrete culverts and now with less-expensive cinder blocks, have been installed since August 2000 in Georgia, North Carolina, Mississippi, Kentucky and Texas. All 18 have been occupied by bats, mostly Rafinesque’s big-eared bats (which are threatened or endangered throughout much of their range), but also by four other species.

Research on these “concrete trees” continues to reduce costs and labor and simplify the logistics of their installation in remote areas, and to demonstrate that alternative roosts can be designed to replace rapidly disappearing large tree hollows.

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