Custom Roosts

Biologist Laurie Lomas checks the artificial hollow tree roost at Trinity River National Wildlife Refuge in Liberty, TX.

Many North American bat species readily use the 3/4-inch crevices of typical backyard bat houses, but other bats need special accommodations. Instead of crevices, some species roost in instead hollow trees or beneath loose bark. BCI and its partners have been developing "tower roosts" – artificial hollow trees – and other innovative options for these bats.

Artificial Hollow Trees

Old-growth trees with hollow interiors are the natural homes for many forest-dwelling bats that mostly roost in small colonies of no more than few dozen individuals. But such trees are often disappearing from managed forests.

Tower roosts, developed over a decade by BCI and its partners, are providing an exciting alternative. Early versions of the towers used large concrete culverts, which showed promise but were expensive and difficult to install. Current artificial-tree roosts consist of rectangular towers built of cinder blocks. They are attracting Rafinesque's big-eared bats and southeastern myotis – rare species that occur throughout the southeastern United States.

For more information about tower roosts, contact BCI's artificial-roost coordinator.

In Costa Rica, meanwhile, German graduate student Detlev Kelm used a BCI Student Research Scholarship to help support his research into the value of very low-cost artificial-hollow-tree roosts for enhancing the regeneration of cleared rainforest. His extensive research used roosts built of concrete-and-sawdust slabs to attract fruit and nectar bats to damaged forests, then documents a dramatic increase in the dispersal of seeds of pioneer plants – the first to grow as clearings begin to recover.

Innovations

Bat Baffles

If you want to install bat houses in a building, you don't have to build an entire bat house. You can be creative as long as you remember to keep the roosting crevices to approximately ¾-inch. Here are some examples:

Tony Koch checks the bat houses in his barn in Stayton.	Bat baffles inside the Campbell Tower at Shangri La Botanical Gardens, Orange TX.

In the Netherlands, bat ecologist Erik Korsten adapted nursery-house plans from BCI's Bat House Builder's Handbook to build and install some of the very first large bat houses in Europe, where bat boxes had always been little more than tiny, modified bird houses. The innovative bat house, installed in 2004, became very popular with pipstrelles a year later, and was soon being emulated around the region.