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  • Writer's picture Lorna Visser

Can fake trees save real bats?

Snk’mip Marsh goes completely batty with installation of BrandenBark structures

Photo below: A tree technician installs BrandenBark at one of the Valhalla Foundation for Ecology's nature sanctuaries

Four leading-edge bat roosting structures have been installed in a nature sanctuary located in the west Kootenay region of British Columbia, Canada, a sanctuary stewarded by the Valhalla Foundation for Ecology (VFE).

In September 2023, four trees at the VFE's Snk'mip Marsh Sanctuary were modified for the installation of BrandenBark™, an artificial roost structure that mimics the natural roosting habitat of tree-dwelling bats.  The installations were done in partnership with Wildlife Conservation Society Canada (WCS).

“Because this area has been heavily fragmented and degraded by logging and human development, old trees with loose, sloughing bark (the trees many bats need for roosting) are disappearing.  So, when we were contacted by WCS asking to install bat habitat-enhancement structures at Snk’mip, we jumped at the chance,” said VFE director Lorna Visser.

BrandenBark™ roosts -– sheets of synthetic bark designed to simulate the conditions, including the micro-climates, that bats prefer in natural structures — are installed high in a tree after technicians turn the tree into a snag.  The synthetic bark is attached loosely to the tree in such a way as to seal out rainfall, but with a gap of several inches at the bottom so bats can shimmy in under the slab of artificial bark and move around within it.

“Once they discover these trees, bats will roost under the BrandenBark™ and shift around depending on the temperature,” said bat biologist Heather Gates, who supervised the installations at Snk’mip.  She's become something of an expert: WCS has so far installed 90 of these structures at 23 locations throughout the region.

Gates and other WCS technicians will be back in the spring to install mesh guano traps under the structures to collect bat droppings, for species identification.  In addition, WCS has been monitoring bats at the sanctuary for many years using acoustic microphones that pick up bats’ echolocation sounds: the high-frequency clicks, squeaks and chirps that are different for every species of bat.

“The Snk’mip nature sanctuary provides a great place for bat enhancements,” said Gates, “it has a large open water-body for them to swoop down and drink from, and a healthy ecosystem providing lots of insects for them to eat.”  

The natural habitat available for bats at Snk’mip has been substantially expanded and enhanced by the VFE restoring and expanding the Snk’mip wetland itself. 

The restoration work was funded by the Columbia Basin Trust and many other foundations including the Slocan Valley Legacy Fund, as well as by generous donations from community members and a lot of volunteer labour.

A former industrial and residential site, VFE restored the property by decommissioning and replanting a sprawling, interlaced network of bulldozer roads, converting formerly degraded areas into ponds and pools, filling in and completely restoring a gravel pit, and building new ponds in upland areas using pond liners.  More than a thousand native-species plants (bushes and tree seedlings) were planted (many by local school students) and, each fall, areas of the property are seed with native grasses and sedges. 

“The monitoring study we conducted (see related post: ‘We're thrilled! Proof we're protecting at-risk critters at our nature sanctuary’) shows what an amazing rebound this restoration project has provided for nature,” said Visser. “We have substantially improved and expanded this habitat, including for bats.”

Visser notes that old-growth wildlife trees are important not just to bats but also to a myriad of other species such as woodpeckers, owls, cavity-nesting ducks, and fur-bearers such as marten and fisher.

Gates adds that bats are amazing creatures: Bats are the only flying mammal, they are the primary consumer of nighttime insects (eating huge numbers of pesky mosquitoes), bats can live to be more than 40 years old, most female bats give birth to just one pup per year, and British Columbia has the highest bat species diversity of all the Canadian provinces.  Good reasons to help save our furry flying friends!

At right: Lorna Visser, Director of the Valhalla Foundation for Ecology, admiring a newly bat-modified tree

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