Assessing Wildlife Damage in Your Forest

Deer, and to a lesser degree elk, are commonly seen in King County, especially in areas with tree cover and suitable forage, or food sources. Unfortunately, landscaping, gardens, young tree and shrub seedlings are common targets for deer and elk and their presence can impact landscaping and restoration efforts by damaging or killing desirable vegetation.

A mature deer can eat 4 to 8 pounds of food a day while a mature elk can eat 15 to 20 pounds every day, and both animals are fairly non-selective when dining on vegetation. They are more opportunistic and eat whatever is available, especially in the winter months when forage is more limited. Both animals feed by browsing primarily on the current year’s tender new shoots and leaves. This can prevent plants from establishing, maturing and growing tall enough to be less susceptible to or less impacted by feeding.

Some shrubs will never grow tall enough to escape browsing by deer and elk, but tree seedlings are generally safe from browse once they’re 5 to 6 feet tall. The topmost growth and upper portion of the crown will be above the browse line and the tree will be able to continue to grow taller unimpeded. However, they may still be susceptible to damage from antler rubbing or horning by males of both species.

Every year, male deer and elk, or bucks, grow a new set of antlers starting in the spring. Once they finish growing at the end of summer, they enter the rutting/mating season. Antlers are covered in a fuzzy skin called velvet, and part of this annual cycle involves bucks scraping their antlers against young trees to remove the velvet and mark their territory. This rubbing can be hard enough to strip the bark off of trees, which damages the layer of the tree where water and nutrients move between roots and leaves. If bark is stripped all the way around the tree, this water and nutrient transport is completely interrupted and will lead to tree mortality.

Summer is an ideal time to consider installing seedling protection or maintaining and adjusting existing protection. While browse can occur year-round, it is more likely to occur during the winter months when forage is limited. Deciduous species drop their leaves and most herbaceous groundcover species die back for the year, leaving only evergreen vegetation for wildlife to feed on. A majority of rubbing will occur starting in late summer or early fall, once bucks’ antlers are done growing for the year, and continue through early winter. Ensuring seedlings are protected before damage levels increase through the fall and winter will minimize wildlife impact on planted seedlings

These photos show examples of how to identify browse and rubbing damage along with a range of management and prevention options and their pros and cons. Other management and prevention options exist, but the ones discussed in this post are generally the most cost-effective and suitable to the widest range of situations, as well as the most likely to be successful if property installed and maintained.

Browse damage

• Since deer and elk have no upper incisors to cleanly bite foliage, branch ends that have been browsed have a torn or jagged appearance when compared with clean-cut damage from rabbits and rodents.
• Damage will occur from ground level up to approximately 4-5’ off the ground.
• Typically, just new growth is targeted, but branches can be browsed down to the stem if food is scarce.
• More prevalent on trees out in the open or along forest edges – easier access for wildlife.
• As much of the crown should be protected as possible, but at a minimum the topmost part of the crown needs to be protected so the tree can continue to grow taller.

Rub damage

• Bark scraped off trees generally less than 3” in diameter.
• Branches are typically short stubs from being snapped off from rubbing as well.
• Can be distinguished from rodent damage due to the absence of tooth marks in the exposed wood.
• More prevalent on trees out in the open or along forest edges – easier access for wildlife
• Generally, damage is from ground level up to 4 to 5 feet off the ground; protection efforts should focus on this portion of the trunk.

Management Techniques

Natural/chemical deer repellents

Pros

• Easy to apply
• No materials to purchase, install, or dispose of
• Can protect against a variety of animals, not just deer and elk
• Can protect against both browse and rub
• No visual impact to forested or natural areas

Cons

• May require reapplication after heavy rain events
• Animals may adjust to certain smells/tastes after time
• Can be expensive for protecting larger numbers of plants
• Need to reapply at least several times every year that protection is needed
• Will be less effective if wildlife populations are high, other forage species are limited, and/or plants being protected are highly palatable to wildlife
• Not all products are equally effective; may need trial-and-error to find the most effective product in your local area

Plastic/mesh tubing

Pros

• Moderately effective against both browse and rub
• Cheap
• Relatively easy to install during planting, especially on smaller seedlings
• Increased visibility of seedlings helps locate them for future maintenance
• Tubes can be reused on future plantings if they’re still in good condition

Cons

• Labor-intensive to install
• Require annual adjusting to ensure continued protection of seedlings
• Some plastic tubes degrade quickly in full sun
• Harder to install on taller, more mature saplings
• High visibility of tubes may impact aesthetics
• Will restrict proper lateral branch growth, especially if not adjusted as the tree grows or if tubes are left on too long
• Wildlife can sometimes pull tubes off of trees

Individual tree cages: chicken wire or other metal fencing

Pros

• Very effective against both browse and rub (smaller metal cages may allow some browsing of lower lateral branches)
• Easy to install, even on larger seedlings and saplings
• More permanent than tubes
• Typically, won’t require any adjustment if installed securely
• Less visually noticeable
• Can be reused for future plantings

Cons

• More expensive than plastic tubing
• Time-consuming to build and install wire cages
• May still require adjustment and maintenance
• Requires a large amount of cage material for larger plantings
• Metal must be disposed of or recycled once protection is no longer needed
• May restrict proper lateral branch growth if cages are too small

Fence T-posts or rebar

Pros

• Effective against rub
• Less visually noticeable
• Permanent, no need for adjustment
• Can be reused for future plantings

Cons

• Expensive
• Labor-intensive to pound posts in, especially in heavy clay or rocky soils
• Heavy to transport to each seedling
• Does not protect against browse
• Metal must be disposed of or recycled once protection is no longer needed

Plastic or mesh tubing can be purchased through KCD’s Annual  Native Bareroot Plant Sale and Community Fair. For more information and to sign up for alerts when pre-orders open in November:

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An internet search for “plant protection tubes” will also direct you to various forestry product suppliers.

All photos were taken by KCD Forestry staff unless otherwise indicated.