We had a big tree come down during one of the early winter storms. Is it disruptive or harmful for wildlife to leave a downed tree, and should we have it removed? Or is it better for our backyard plants and animals to just leave it there?

– Blake, Cape Elizabeth

Downed trees can be beneficial for backyard wildlife. Photo courtesy of Maine Audubon

This is a great question because much like our social conditioning to having perfectly mowed lawns, addressed in my Nov. 29 column, many people have a preconceived idea that the forest floor is a bare place. The best way to think of this is that the early winter storm was a natural event (the increased frequency and severity of storms that we’ll see due to climate change is a topic for another column) and the toppling of this tree was nature’s way of changing the forest.

Downed trees provide many benefits to wildlife of all types, maybe even more than when the tree is standing. First, the fallen tree will provide shelter for lots of smaller birds and mammals, similar to how you’ll see lots of sparrows and chipmunks taking advantage of a brush pile – this tree is nature’s brush pile. Many insects will move in and help with the decaying process, and those hungry insects then become a great source of food for the next step up the food chain – from porcupines to woodpeckers.

The new opening in the canopy will let in light and help new and different species of plants to grow, which adds to the biodiversity of your backyard. Do keep an eye on those plants; invasive species thrive on disturbance so it is good to make sure no Japanese barberry (berberis thunbergii), Norway maples (acer platanoides), or other non-native plants are taking advantage here.

Honestly, the only way I can see a fallen tree being harmful is if something non-native takes its place. Maine Audubon’s Forestry for Maine Birds program, which targets loggers, foresters, and larger land owners, has great information on the importance of diverse forests and many more details on benefits for wildlife. Learn more at: maineaudubon.org/FFMB

It can be really fun to use this as a personal study site, too. Check it regularly and see what is using it – I bet the list will grow quickly. In winter look for tracks after a new snow. You’ll often see mammals using old trunks as highways to navigate through the woods. That bit of elevation also provides a good lookout for red squirrels during a meal. Look for pieces of acorns or pine cones that have been pulled apart and discarded at these tiny vistas. Come spring, carefully look for salamanders under decaying pieces of the trunk or branches, and as various invertebrates start breaking it down, watch for a pileated woodpecker to show up with its huge chisel-bill. Even if you miss the bird, you’ll spot its handy work.

It is worth mentioning that if you are going to have any tree work done, winter is a good time. Getting this done ahead of the nesting season is important, and the frozen ground will be less disturbed by any heavy machinery or falling branches. Check out Maine Audubon’s Forestry for Maine Birds project to learn what even a small patch of woods in your backyard should look like.

WINTER IS A GREAT TIME FOR BIRDHOUSE MAINTENANCE

Dear Doug,

Thank you for your helpful information in answering questions for birdwatchers. My son, Nate Carr, and his son were skating on a pond near their home in Falmouth. Nate knows I am a birdwatcher, so he posed with this birdhouse in the background. Which bird would be attracted to this birdhouse?

– Thank you, Eileen Carr

Eileen shared a photo of her son and grandson posing in front of a birdhouse which is interestingly placed on a snag right in the middle of a frozen pond. This may seem like a risky place to nest but you may be surprised to learn how much diversity there is in Maine’s cavity-nesting species.

It helps to begin by thinking about the purpose of a birdhouse, which is to replicate a cavity in a tree. There are a handful of primary-cavity nesters in Maine – species that make their own holes in trees for nesting – and woodpeckers are the most obvious. But even some birds like chickadees will excavate their own cavities. These birds typically only use that cavity for one season, and then in the following years the hole is used by a whole suite of other birds we call secondary-cavity nesters.

Dead trees on the landscape are common places to see cavities that are used by our secondary-cavity nesters, but, as briefly mentioned in my response to the other question in this column, there is a social stigma against dead trees and they’re often cut down prematurely. Sometimes it’s necessary – no one wants a dead tree falling on their house or car – but putting up a birdhouse can help replace that otherwise scarce resource.

Many people know the common secondary-cavity nesters: Eastern bluebirds and tree swallows, and the list goes on. In Maine, we have everything from falcons (American kestrels) to ducks (wood ducks), to flycatchers (great crested flycatcher) and even some owls. There are many different types of boxes, and getting them in the right habitat is the key. This brings us back to Eileen’s question. That large birdhouse out in the middle of a pond is perfect for a wood duck, or maybe even common goldeneye farther north in Maine.

Winter is a great time to do a little birdhouse maintenance – you can access areas (like the middle of a pond) that would otherwise be challenging in the summer, and no one is nesting yet. A quick cleaning can help remove parasites or other unwanted things from the box, but don’t worry if you forget, or can’t, clean them. After all, no one is going around cleaning all the natural cavities; the birds can do it themselves.

Do you have a nature question for Doug? Email questions to [email protected] and visit maineaudubon.org to learn more about virtual and backyard birding, online classes and other programs about wildlife and habitat.

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