Crews thin trees at Mark Twain Lake to help 200,000 endangered Indiana bats

As per the report, treatments are carried out in late summer and early autumn, when trees begin moving nutrients and stored energy toward their roots in preparation for winter. That movement helps carry the herbicide deeper into the trees.

Every autumn, as forests begin to thin naturally, another kind of clearing takes place around Missouri’s Mark Twain Lake. This time, the goal is not timber production or development, but making room for one of North America’s most vulnerable bats.

According to a report by WGEM, about 200,000 endangered Indiana bats spend the warmer months in the forests surrounding the lake before heading east to hibernate at Sodalis Nature Preserve near Hannibal. That represents roughly one-third of the species’ entire North American population, making the landscape an unusually important stronghold for the bats.

Opening up the forest

The U.S. Army Corps of Engineers, working with The Conservation Fund, has begun forest stand improvement work across public wildlife management areas around Mark Twain Lake.

The project focuses on reopening flight and foraging corridors that have become increasingly crowded after decades without active timber management, states the online report.For more than 40 years, shade-tolerant trees such as sugar maple and ironwood have filled in the forest’s middle canopy. While these trees are part of a healthy woodland, their dense growth can block sunlight and create obstacles for bats moving between feeding areas and roost trees, states the report.

Rather than clearing large sections of forest, crews are using a targeted technique known as hack and squirt. Workers make small cuts around the trunks of selected trees and apply herbicide directly into those openings. The method allows crews to remove specific trees while leaving the surrounding forest largely intact.

Dead trees become bat habitat

One of the unusual benefits of the approach comes after the targeted trees die. They are left standing, gradually becoming snags that can remain part of the ecosystem for years.

Indiana bats rely on cracks, crevices and peeling bark in mature trees for roosting, particularly in the overstory oaks found throughout the area. Depending on the tree, a treated snag can provide useful habitat for roughly four to 10 years before naturally breaking down.As per the report, treatments are carried out in late summer and early autumn, when trees begin moving nutrients and stored energy toward their roots in preparation for winter.

That movement helps carry the herbicide deeper into the trees.

More than a bat project

Opening the middle layer of the forest is expected to benefit more than Indiana bats. With fewer trees blocking the canopy, additional sunlight can reach the forest floor, encouraging native grasses, flowering plants and young oak-hickory growth. Those changes can improve habitat for deer, wild turkey and other wildlife that depend on the forest understory.An initial 30-acre phase was completed last year, and crews are now working toward treating more than 250 acres around Mark Twain Lake by November 1. The wildlife management areas remain open to hikers, hunters and other visitors during the work. Visitors are being asked to give forestry crews room to operate as the habitat restoration continues.Images Courtesy: istock