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snags, or wildlife trees: cultivate, don’t cart away, dead, dying, and hazard trees

brich snag two trunksSNAG. Not as in my pantyhose, which I haven’t worn since departing the corporate world for an existence where fashion has little status. Snag as in wildlife tree—as in a place to nest or den; a source of food for insects, who are in turn food for many other creatures; a perch for lookout, and more.

The other day, I had to finally reckon with a 40-foot-tall old, twin-trunk birch that was in decline, and dropping massive portions of its crown on two small outbuildings. To the arborist crew’s surprise, I didn’t let them take it all down, or even cart away most of what had to be cut. Here’s why:

Biomass.

Removing all that living or recently living mass of organic material would be a big loss, biologically speaking, for the complex organism I call my Northeastern garden, the one corner of the world I am completely responsible for.

“By some estimates,” the National Wildlife Federation says, “the removal of dead material from forests can mean a loss of habitat for up to one-fifth of the animals in the ecosystem.”

Some experts recommend an ideal snag population to be about three dead standing trees per acre—that’s how important they are.

Don’t remove any more of a dying or damaged tree than is required for safety reasons–and “safety” is of course different in fire-prone areas than in my Northeast location. Even a high stump can support a lot of wildlife action, compared to a clean cut made at ground level, or worse, a ground-out stump.

removal of birch 2Lowering the larger, cut-down limbs and trunk portions to the ground, and allowing them to rot there as if they had fallen naturally, is also better ecologically than carting it away. Make like the tree fell beside where it once grew (even if logistics require you to do it in big pieces, rather than whole).

birch trunk on groundWho will thank you?

  • Cavity nesters (from pileated woodpeckers who can actually excavate, to secondary cavity nesters such as flying squirrels, wood ducks, and even bluebirds).
  • Any creature that is at least partly insectivorous, since insects and other small invertebrates will show up to feast on the carcass.
  • Birds such as hawks and owls, who want a good vantage point to survey the area for prey.
  • Animals as small as salamanders and snakes or as large as bears, who may enjoy the hiding place a fallen tree provides. One of my favorite birds, the shy little brown creeper, likes to nest beneath loose bark, for instance, and other animals cache foodstuffs for later use there, too. The list is long.

pileated woodpeckerYears ago, when one trunk of a multi-stemmed old apple here lost its crown in a storm, we simply stabilized that snapped-off trunk by taking off anything that was hanging, and left it otherwise intact. I’ve spent more than 15 years watching who shows up to enjoy it along with me (including the pileated woodpecker, above), and the distinctive evolving character of the elderly tree (seen dormant, below, with its hellebore underplanting).

apple snag with helleboresA word or two about my newest snag, which isn’t perfect: Ideally, there would have been some lower branches to leave intact, to make it a more attractive destination to wildlife, but the giant twin trunks were already naked until past 20 feet, where the die-off has set in. I could have had the arborist create jagged tops to each trunk to make it more naturalistic and speed decay. If the tree had not already had plenty of cavities, we could have started some–but the birch was already like a condo complex.

And this: I should have cut the trunks down even lower, because they could still potentially fall on one of the sheds. Looking at the condition of the lower wood from the point we left standing, though, I think that’s unlikely for at least another five years, so I was happy with the risk-reward ratio in leaving the snag as big as it could be.

I expect the birch to play host to a lot of happy visitors between now and then.

how, and why, to cultivate a snag

WASHINGTON STATE Department of Fish and Wildlife, in this detailed pdf (also available from this link), provides how-to on identifying which trees are snag material (clues like woodpecker holes, fungi on the bark, running sap or die-off in the upper branches are among the hints). It also tells how to accelerate the process, or turn a healthy tree that needs to be topped for safety reasons into a wildlife tree. (It’s also available as a web page if you prefer that to a pdf version.)

  1. joanne vidal says:

    Very informative. We have an old rowan (mountain ash) that every arborist who comes near the place offers to take down, now I have science on my side to keep as much as we can of it. The woodpecker loves it. We cleared some of our regrowth-covered land this fall to get unshaded garden space sloping south (we are surrounded by woods) and although I appreciate the sunlight I did feel bad for the birds that loved it and we did remark the falloff in numbers at the feeders near the house. Now I also know what to do with a couple of birch that were recently snapped off in winds. Thank you

  2. Nancy Warberg says:

    Hi Margaret,
    I totally agree with your article concerning the need to leave some dead trees and underbrush in our environment. We are too tidy at times and the birds and other animals suffer. I intend to bring up this topic in my garden club (which may shock some of the ladies who think that their gardens must be immaculate).

  3. Eileen says:

    This article did my heart such good! My 3 old birches have been dying in bits and pieces for decades but have also been the home to many species of birds and other critters over the years. I planted an old climbing rose at their base years ago and I can’t tell at this point who is supporting who. All I know is that come Spring both the rose and the birches come alive w color and song and I rejoice in their beauty. And in winter the trees are alive with birds flying back and forth under their cover to get to our feeder and bird bath. I’m so glad we never listened to neighbors and gardeners who have told us to bring the old trees down. They were here when we moved in 20+ years ago and will be here until we leave. Thank you for the affirmation that all phases of the life cycle have an important role in our natural world.
    Regards, Eileen

  4. Beverly, zone 6, eastern PA says:

    I keep a brush pile under some rhododendrons, near a fence line and also near a gutter runoff, and each year I see more and more salamanders, all sizes and three colors (species?). It’s so easy to place a fallen branch onto this brush pile instead of piling it elsewhere and eventually carting a whole load of branches off to the township drop-off. My many mature trees drop branches regularly and I utilize all of them any way I can. We still have a Hurricane Sandy casualty, a spruce tree stump, pulled out so we could use the footprint, but saved under the edge of another spruce. I intend to keep it there, too.

  5. Lacey says:

    I just rescued the coolest looking hollow, rotten log off the curb. I can’t believe someone wants to throw that away! I’m going to plant the holes with something – an epiphyte fern maybe? And it can nurse my garden as mother nature has her way with it. I can’t wait to see what mushrooms declare it home.

    I love it when you write about things like this… it’s nice to find likeminded people. My neighbors think I’m nuts.

  6. Lisetta says:

    What a coincidence….I woke up this morning to the sound of a pileated, hammering away 15 feet up on the remains of a tree that we needed to have taken down 4years ago …..I insisted they leave part of it standing….and not haul away the wood….they thought I was CWAYZEE…..however I prevailed. I wanted a support for a clothesline so I could have the smell of fresh air in my sheets and a home for wildlife. I just never knew (until I read your blog this morning) that it is called a : snag. Thanks Margaret!!!!!

  7. nancy giges says:

    This is so interesting and something totally new to me. I wish I had known before I took down trees all the way to the ground in the past few years (but I didn’t have the stumps ground out).

  8. Donna Frankiewicz says:

    Love this article!! I’ve been doing this right along, partly out of “laziness”, and mostly out of an idea that my downed trees are a great “hidey place” for the birds and small animals here in the forest of George Washington State Park, Bigfork, Minnesota. You have validated my theory! Love your site, Margaret <3

  9. Judy says:

    I love this post. It’s interesting and educational to leave a good portion of tree habitat for so many wildlife dwellers. As long as the danger of dead trees is managed in a way that keeps personal property intact. I learned something new and will be more aware of how cutting dead trees down the the stumps impacts the wildlife.

  10. Nancy says:

    Thanks, Margaret! Your article reaffirmed our decision not to remove various dead or dying trees amidst the forest that surrounds our property in Spencertown (NY). Indeed, we have considerable activity from Yellow-bellied Sapsuckers, Hairy and Downy Woodpeckers, as well as Flickers, the Pileated and our other regular backyard friends.

    We also have a very large pile of mixed branches, weeds, and other matter from our back-breaking yardwork. I really want to cart it off (truck it out!), but there’s also a lot of activity there with creatures of all kinds. As Beverly from PA noted, it’s a lot easier to add to it at this stage!

    Dan and Nancy

  11. Kathy Sturr of the Violet Fern says:

    Yay for you Margaret! I am so happy you left a snag for the critters that grace your garden. You have such influence that I know will reach many. I left a snag to an old Box Elder but new house owners took it down to the ground. However, I used the wood chips and some of its large logs in my garden so it lives on. The wood chips created the fertile ground of what I dub my “Woodland Edge,” and the logs house birdbaths and containers. I also have a few “nursery logs” laying around in my garden beds. I love to look underneath the bird baths when I refresh them – there is always something creepy crawly and there are some really funky fungi that grow, too. Solitary bees might also burrow in. I’m sure you’ll share more with us as visitors and time work magic.

  12. Sharon B. says:

    Margaret, I have thought a lot about this post since I first read it, having recently taken down a dead cherry tree. Aren’t you surrounded by forests with dead and dying trees, fallen branches, etc.? If so, why do you feel you need to leave a dead tree on your property? Is it to attract birds where you can see them?

    I leave brush piles and unkempt areas to encourage birds in my yard, plus there’s an area across the street with plenty of dead trees and brush. So I know the local birds have habitat. So just wondering if you’re providing needed habitat or a better view for yourself (or both, of course).

    1. margaret says:

      Hi, Sharon. The biomass of the twin-trunk tree has been a member of the community here for many, many decades (it was already giant when I got here 30 years ago) so I guess I figure it needs to decay in roughly the same spot from whence it emerged. Though I couldn’t just let it fall when and where it wanted without losing the two sheds, I could do the next-best (and next-least interfering) thing: top it, and lower it to beside where it stood. That’s my general theory: never take away anything you don’t need to, but try to recycle in place; never bring in anything (bagged amendments etc.) that you don’t need to…to keep inputs/outputs to a minimum.

      1. Sharon B. says:

        Hi Margaret. I forget to check for a reply until now! Perhaps because I know you get so many inquiries/responses, I wasn’t sure whether there would be a response. But as we slowly awake from snow and cold, I walked around my garden today and thought about snags. And your response makes so much sense: “never take away anything you don’t need to, but try to recycle in place.” Thank you for adding this piece to my puzzlement about snags.

        1. margaret says:

          You’re welcome, Sharon. Hope it helps as inspiration. I’ve been enjoying watching who pops out of what holes in what decaying trees around here, and will be happy to see who decides to make use of my manmade snag perhaps this season.

  13. Doreen says:

    The tree company was surprised and my neighbors were not pleased but the birds and wildlife are ! No danger but “unsightly”- oh well !

  14. Rita Wilson says:

    Margaret, just now seeing this post. Love the article and especially the result you chose for your tree and area. I am saving limbs, logs, etc. to start a hagelculture garden

    1. Rita Wilson says:

      Somehow that last comment got sent before I was able to correct my misspelling of the long word hugelkultur. While I looked up the word, maybe the cat stepped on the computer. They are so good at helping. I’m starting that garden soon and am so excited about it. You posted an article on that also and I had previously read two others. Small yard, excellent, class #1 soil in my area, so taking advantage of all that Mother Nature has offered.

  15. Linda Andrews says:

    We had a mature silver fir die in our front yard about 7 years ago. We had an aroborist shorten it and rough up the top, and left it as a snag. This year, we shortened it again so it won’t be too dangerous as it continues to rot. Tons of birds use the snag, includinf nesting chickadees, and it has given us a lot of pleasure. We keep other dead wood in the garden as well. The snag has been a conversation starter and provides an opportunity for us to gently educate. Thanks for this blog post!

  16. Kathy says:

    We had to have a large dead pine removed being to close to the house and a safety issue. What we did was had it cut leaving an 8 ft stump. We attached a large bird feeder to the side and a suet feeder from the top. Attracts a large variety of birds along with a few determined squirrels and at night two very large racoons. My son in law who has stump grinding business thought we were crazy but we love it. Last summer I grew a black eyed Susan vine around it and it was beautiful. It is so important to do all we can for our ecosystem,which is under attack from all sides. Thank you Margaret for all you do to inform and educate your readers.

  17. pat says:

    love this article. I was forced to drop a 60 ft hardwood that was only 10 ft from my house. It was rotting out very bad and leaning towards the house. It’s still laying where it fell so I guess I’ll just leave it there now. thanks for all the info you share.

  18. Terry Gardner says:

    I had a tall shaggy bark hickory that broke off about 15 feet up several years ago during a derecho. It has served a pair of pileated woodpeckers well. They come to my suet feeder in the winter and have been debugging and debarking the snag since.

  19. Cathleen Maloney says:

    We had to cut down two beautiful very old birch trees in our backyard this summer after they had been invaded by bronze birch borers. I still grieve over losing those trees. They are why we bought this house. Whenever we were outside, we were in danger of having limbs fall on our heads. We had to cut one down to a four foot stump because it was split and close to a neighbor’s house. It now supports two feeders and will have seed bearing plants around it this spring. The bigger birds frequent it every day. The other one we left at eight feet. Our surrounding neighbors told me it was an eye sore. However, it is supporting two feeders and a suet feeder. This spring we will put a rough roof on the top for shelter from the rain here in Oregon for our fathered friends. The birds love perching on the limb stumps and the woodpeckers continue to work it over. We are enjoying our snags and so are the wildlife.

  20. Karen says:

    I would love to learn more about my small forest area out back (one acre) of very old white oaks that make a home for foxes and other creatures.

  21. Theresa says:

    I love this concept and also providing brush piles at the woods end for wildlife shelter for the harsh winters..thank you

    1. margaret says:

      I was outside today and noticed that a pileated woodpecker is making a big opening in one side of my birch snag…so I think it’s working! : )

  22. Teri Clark says:

    We have a continuous brush pile surrounding our two acre wooded property, acting as a fence, to keep our yorkie in and coyotes out. As limbs fall they are added making a 5 foot tall, 5-6foot wide border. There is also a 20foot tall maple snag hosting a myriad of critters and a host of stumps, chosen for their architectural beauty, in the stumpery garden. Paradise!!

  23. Nancy says:

    I need to move a semi dwarf apple due to construction, but thinking it would make a better snag due to all the moss on the bark. Is it possible to cut it down to the soil line and then dig a really deep hole, like 3 feet and “replant” it? I’ll also grab the stump when they excavate after reading your article!

    1. margaret says:

      I doubt it would be very stable without its root system, but you never know! I have sometimes simply dropped the trunks of trees that were too unwieldy to stand any longer, and let them rot near where they once stood — another way to keep the “biomass” of that carcass in the garden environment.

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