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.