Thursday, May 7, 2009

Plant a standing snag for wildlife

Standing snags (dead trees) are a common structural component in forests and riparian areas. Their importance in the wild is well known, studied and understood. But they can have the same beneficial role in your garden as well. A standing snag may be one of the best features to attract a variety of wildlife species to your yard. Although birds are just one of the many animals that will benefit from a snag, to give you an idea of a snag’s importance, up to 45% of bird species in the forests of North America use cavities found in snags.

The rationale behind using nest boxes is that you are providing a replacement for habitat lost from the removal of dead or decadent trees. Dead or dying trees are the first thing to get removed in managed landscapes (whether a backyard or city park), or even preparing up your yard for a wildlife garden. However, by leaving dead trees standing, or even planting a dead tree, you can add habitat, structure and yearlong visual interest to your yard. This is a great gardening project for people concerned about their lack of a green thumb.

What species of tree makes a good snag?
Anything. But in this area cottonwood (Populus trichocarpa), aspen (Populus tremuloides), ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii ) or lodgepole pine (Pinus contorta) will probably be the best- they are the ones birds, insects and other animals are used to. Although cottonwood and aspen make great snags, they will probably be shorter lived than the pines or fir.

Where can you get a snag?
You may have one and you don’t even know it. Sometimes, the best snag is simply a tree in your yard that has gotten too tall, is diseased or is just unwanted. Rather than replacing it, removing it, or healing it, let it die in place. You could prune it back to shape to an aesthetically pleasing standing snag, and kill it in a variety of ways (from girdling, to a herbicide treatment to heavy handed pruning- obviously without cutting it down), and leave it. For example, in our backyard, one of the first trees we planted was a 4’ Ponderosa pine. It has grown a lot faster than I expected, and right now it is a great size, but my long-range goal for this tree is as a snag in the yard (its days are numbered).

You can also find snags that are suitable for firewood cutting (check local laws about cutting or removing standing or fallen trees from forests, and certainly don’t remove any from riparian area or waterways), in slash piles, or even in your neighborhood where trees are being removed. Contact local tree services- they might even deliver one to you.
How big should a snag be?
As big as you can manage. However, check with building codes for height restrictions in your area (probably not a big deal). Also consider the size of your garden, and adjacent buildings. In general, try to get a snag that will have at least 10’ exposed above grade (so a total length of at least 15’). The larger the diameter of the snag the more useful it will be to wildlife. For example, to get nuthatches or flickers to excavate a nest, the diameter needs to be at least 8-12” where the snag is 6-10’ from the ground.

How to plant a standing snag
Typically strive to bury at least 25-30% of the length of the tree in the ground and set it as you would a fence post. Dig the hole at least below the frost line in your area, and as deep as 30% of the snag length, fill the bottom of the hole with about 4” or gravel or cobble for drainage, insert the snag, check for plumb and back fill and compact the soil around the base. Be careful not to plant the snag under overhead wires or power lines (snag humor- they don’t grow).

Integrate the snag into your landscaping
This is important, make it look intentional and have it blend in with your landscape. A standing snag is a strong structural element in your landscape that can dominate, but with some thought and planning it can blend into the landscape. A snag is a great structure that provides gardeners with an opportunity to showcase climbing or vining plants. In western Montana, if your snag is in the shade, orange honeysuckle (Lonicera ciliosa) or blue clematis (Clematis columbiana) are great vines. If it is in a sunny spot, western white clematis (Clematis ligusticifolia) will be a great addition. Also consider the location for the snag, and place it in a natural surrounding, nestled among trees or shrubs (as opposed to out in the middle of a lawn), and often times it is nice to place on near deciduoius trees so when they lose their leaves in the winter, the snag will provide interest and structure.

They don’t last forever
Eventually the base of the snag will rot (how quickly will depend on the soil type, tree species, age of tree, etc...), so plan for this and perhaps plan to incorporate the fallen snag into your landscaping plans. While you are at it, don’t limit yourself to standing snags, fallen snags also provide a lot of habitat for wildlife and add visual interest and character to your garden. They can also make the base for a brush pile.


  1. Another great idea! Unfortunately because of the small size of my yard, I won't be able to make a big snag fit in my garden, but I'm thinking of making a "snag" out of the telephone pole on my property. Could I nail pieces of wood and branches to a pole like that?

    And my brushpile is serving as a "daycare" for fledgling robins. I found two of them huddled under the dead branches yesterday. Papa robin was a bit frantic so I didn't spend too much time cooing, but what a delightful surprise!

  2. I have a mini snag in a pot, the hummingbirds use it as a perch to guard the feeder. I love the way yours looks in the garden. I'll be on the lookout for something bigger. Your posts are wonderful.

  3. Janina and Peonies,
    Thank you both for your comments.
    I am glad you mentioned the hummingbirds were using you snag as a perch. I forgot to mention in the post that perches are one of the best features of a snag, because of the open and large branches, birds really gravitate toward them.
    So as far as the telephone pole, your idea of nailinf branches to it would probably work well, though you may want to check with the local utility company, first.
    I am really happy your brush pile is working!
    Thanks again,

  4. I love the snag idea, Kim talked me into one years ago. I don't think the birds use it much except as a lookout point. But it is a nice focal point nevertheless.

  5. I'm used to snarky humor on garden blogs, but "snag humor" is a whole new area!

    We have a dead Incense Cedar that the tree man said was sturdy. He trimmed back some branches and we let the wisteria have its wicked way there. Now I know to look more closely for avian activity--thank you!

  6. Hi Daffodil,
    Glad you liked the snag humor- I thought you might appreciate it!

  7. Stumbled across this in a google search, quick question...
    I work for a large Washington state agency and we’re in the middle of a Large Woody Debris (LWD) project in central Washington. Basically we’re thinning a small section of forest that parallels a “wood deficient” creek and then use very low impact techniques to move the down timber into the channel of the creek (To help improve Coho and steelhead habitat). Pretty cool stuff. Now to the questions, after we thin a unit we want to create a couple of standing “soft” snags.
    We have considered girdling the selected tree but would we would like to figure out a way to “open” the tree up. We have considered using climbing gear to top the tree and use a Humboldt style face cut and leave a ton of holding would and then griphoist the tree over creating a “jagged” split top .
    Do you have any ideas?
    I hope this makes since and was not too much to digest …