We see them everyday and essentially most people just ignore them. Hundreds of thousands of dead trees were created a few years ago when the Emerald Ash Borer invaded North America. Communities rallied to cut them down and place restrictions on their movements between municipalities. We’re talking about trees here. With the ash trees killed by the borer it made sense, cut them down and stop the spread! But for other trees, is it a good idea to cut them down or can we leave them standing, or fallen? Well once we set aside property damage risks and human health concerns, we should try to leave them in place as much as we can.
Realizing that many people have small lots, it is a bit unfair to expect them to leave a fallen tree trunk in their yard or a standing dead tree on the fence line. Or is it? As urbanization encroaches, more and more we find that wildlife benefits less and less. What might be an unsightly hunk of wood to us is a home and food for myriad of animals. Let’s explore this a bit.
A fallen tree serves many purposes. It can be food and a foundation for other organisms such as small plants and mushrooms as the wood decays. Insects will probe its rotting structure as they eat the wood, while other animals and plants are attracted to the bounty. Some animals will use the log, as it hollows out over time, for shelter or nesting. The Turkey Vulture is one bird that will nest inside a suitable log. In time, as the log continues to rot, it will fertilize the soil around it and more plants and animals will benefit from the nutrients it releases. Piles of fallen branches serve a similar function but have the added benefit of providing shelter to migrating birds within its complex intertwined stems.
The carcass of a standing tree provides even more benefits to wildlife. The snag, as it is known, is an important lookout point for birds big and small. They can perch on the tallest point and watch for predators, competitors or food. Hawks will perch here and watch for prey below and, when seen, dive towards the ground in pursuit.
Flycatchers will likewise dash out to catch a passing bug. Smaller birds will search the cracks and crevices and loose bark looking for sedentary prey, while other birds will sing for a mate and territory from its outer branches.
The greatest benefit seems to be that the structure provides a home to countless insects, many mammals and numerous birds that nest within its trunk or larger branches. Species such as flying squirrels may nest or roost in an abandoned woodpecker hole. Many birds likewise will either excavate their own nest hole or occupy an abandoned one. Woodpeckers, kestrels, Wood Ducks, golden-eye, chickadees and more will use holes in the tree for nesting. Other species, such as the Brown Creeper or Red-breasted Nuthatch, may nest behind the bark of the dead tree. Chimney Swifts commonly nested inside hollow trees, but now utilize homes and chimneys for roosting and nesting. Bats will also roost behind the bark or even inside the tree trunk in a hole.
My personal favourite tree is a 30-foot tall White Ash that was killed by the borer about three years ago, but it still stands with my neighbour’s indulgence on the boundary between our two properties. I like it because it is a magnet for birds! They come to sit and wait near the feeder, watch for mates, sing from its highest branches or glean invisible food clinging to its bark. Over the last couple of years, I have seen over 72 species sitting in this single tree!
So when you see a dead tree don’t overlook it, take a minute and marvel at its importance in our landscape and cherish the many species that rely on it for survival.
Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line at www.avocetnatureservices.com and on LinkedIn and Facebook.