Selective Tree Thinning
Watch a video of a helicopter helping to thin the forest at Ellsworth Creek Preserve.
Willapa Program Director explains why Ellsworth Creek provides critical habitat for the marbled murrelet.
By Robin Stanton
Could selectively logging trees in an old-growth forest actually help revive a threatened seabird?
Conservancy biologist Tom Kollasch got this counterintuitive idea while he was watching marbled murrelets flying in Washington's Willapa National Wildlife Refuge. The murrelets — a threatened seabird that nests in old-growth forest — were circling small stands of old-growth trees that were blocked by younger trees.
Kollasch knew that the marbled murrelet flies fast but doesn't turn well in flight. “My colleagues and I started wondering if we could open up a path into those trees, if the murrelets would take advantage of it and use them,” he says.
So the Conservancy led a project that used a detailed tree map and a helicopter to surgically remove specific trees in Willapa that surround potential nesting sites. And while the results are still up in the air, the murrelet can certainly use all the help we can give it.
Marbled murrelets are robin-sized seabirds that feed at sea like their cousins the puffin and common murre. But they fly inland up to 50 miles to nest on large moss-covered branches most commonly found in coastal old-growth forests — forests of giant spruce, hemlock, cedar and fir.
The short, stubby-winged bird can fly faster than 40 miles an hour but its lack of maneuverability in flight makes it a challenge for the murrelet to land on a branch. So it's really important for the forest to have openings and corridors under the canopy to create favorable nesting conditions.
Unfortunately, these small remnant stands — ranging in size from a few trees to a few acres — are surrounded and filled in by dense uniform growth of younger trees, which grew in response to more light after logging, making it difficult for the murrelets to reach these nesting platforms.
And with nesting habitat disappearing in southwest Washington because of logging and windstorms, Kollasch knew it was time to act on his observations.
So in Willapa, which is adjacent to the Conservancy’s Ellsworth Creek Preserve, the Conservancy is managing a project in partnership with the refuge and the Washington Department of Fish and Wildlife to see if it can reestablish those favorable conditions.
In the fall of 2008, the project selectively removed some of the younger trees surrounding the remaining big, old trees that have branches favored by the marbled murrelet.
“We came back to each nest tree and mapped every tree around it, and then marked the particular trees that we thought could help open a flight path if removed, but not open the stand up too much," says Kollasch.
This is where the helicopter comes in: Once each hand-selected tree was felled in place, the helicopter flew in with a 200-foot cable to lift the tree out of the forest and take it to a central location for sorting and hauling.
Using the helicopter to haul the logs significantly reduces the ground disturbance caused by the thinning. And the Conservancy will sell the logs and put that revenue back into similar restoration projects, including additional tree-stand monitoring.
Now that the thinning has been completed, the Conservancy will continue to monitor these stands to see if marbled murrelets do begin to use these trees as nest sites. And Kollasch is taking a long view on success.
“If the murrelets show up within two years, that would be incredibly exciting,” he says. “But even if they don’t, the habitat will continue to develop. It could take five or 10 years to learn whether this idea is successful."
"We're losing habitat all the time — small remnant old-growth stands are still being logged with surrounding second-growth stands," Kollasch adds. "Windstorms are devastating habitat. In the meantime, it would be wonderful if we find new ways to quickly restore habitat for these valiant little birds.”
(March 2009)June 11, 2012
Robin Stanton is a media relations specialist for The Nature Conservancy in Washington state.