Healthy Habitat Piles — Or, Being Down With Downed Wood

Ken Bevis, Wildlife Biologist, Washington State Department of Natural Resources, ken.bevis@dnr.wa.gov

Providing habitat complexity is the best way to ensure diverse and rich wildlife populations on our forest lands. Dead and down wood, including small pieces, are key elements, and through active management we can provide much of this habitat.

Many species of wildlife utilize dense collections of woody material in shrub patches or down wood concentrations. Birds, such as song sparrows and juncos, mammals, including snowshoe hares and chipmunks, reptiles like garter snakes, or amphibians like salamanders or toads will rest and breed in the relative safety of the complex network of twigs, logs and leaves in these habitat features.

Forestry offers numerous opportunities to maintain and even enhance this habitat.

Thinning and harvest activities always generate considerable quantities of woody and green material that must be dealt with in some manner. Choices for slash management include leaving it where it falls, burning (piles or broadcast), lop and scatter, chipping, or constructing and retaining habitat piles.

There is incredible habitat value with piled material. In fact, creating a loose pile of slash, using logs and branches, may be the fastest known way to create beneficial habitat structure.

The insect fauna of our forest ecosystems is varied and complex.

The vast majority of insects do not pose problems for forestry, and often perform useful ecosystem roles such as nutrient cycling or preying on populations of other insects. “Bad bugs” are generally considered those that defoliate trees to an excessive degree or consume cambium, which can cause tree death.

Despite the understood value of piles for habitat, there is discussion, even debate, over the risk of increased populations of “bad bugs” in these piles.

The good news is that the risks are largely restricted to management of pines in drier forests of Eastern Washington. Rob Lionberger, the DNR Stewardship Forester for the region, cautions leaving any pine slash less than six months old on the ground between April and September. This quote form Melissa Fischer, DNR’s forest pathologist for Eastern Washington explains why:

“We have been seeing a change in the pine engraver’s life cycle the past several years.  Historically, the pine engraver had 2.5 generations per year (i.e. from egg to larvae to adult laying eggs). Recently, there has been a full third generation. This elongates the time period where you would not want to leave pine slash/ logs on the ground. I consider October-December as the low-risk time period, July-September as medium-risk and January-June as the highest-risk time periods.”

Basically, if small-diameter material is created during that late summer to early winter period, the cambium will have time to dry out and no longer host the beetle for extra life cycles. However, a large-diameter tree (think more than 8 inches) with intact bark harvested during that time will not be able to dry out before the beetles fly in the spring.

In other words, play it safe by building your habitat piles with small-diameter materials harvested between October and December. Also, materials from other species that do not harbor “bad bugs” (willow, for instance) can be used in piles any time of the year.

Western Washington’s wet forests also have a variety of insects hoping to feed on the cambium of live trees.

However, in this region they require large amounts of recently dead, large-diameter wood (think of a big windstorm) to build populations that can significantly impact a stand of healthy trees nearby. As a result, insects are rarely a major forest health issue on the west side and are generally considered “secondary” pests.

In Western Washington cutting small-diameter materials (8 inches or less) for habitat piles will usually not result in increased insect populations, regardless of timing.

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Side view of a habitat pile with larger materials on bottom and fine materials layered on top, including a perch for birds. (Illustration by Ken Bevis, DNR)

I recommend having at least two habitat piles per acre, especially in areas of active management. This provides adequate wildlife habitat but does not amount to enough woody debris to be a serious wildfire hazard.

The habitat piles can be constructed by hand, placing larger materials on the bottom several layers deep and covering with finer materials on top. These should be at least 10 feet in diameter and 5 feet high, to provide some interstitial space for small animals to get inside.

Be creative and consider what might be able to live there. Make an entrance big enough for a bobcat or coyote. Layer small logs and branches into a roof on the third or fourth layer to provide dry cover in wet winters. Build the pile around an existing shrub. Old slash piles often have shrubs growing out of them and provide excellent habitat. You will be amazed how much use they get, especially from smaller wildlife.

Send me pictures of your best habitat piles! But don’t feed those bad bugs …

A Rotten Story: Forest Decomposition

The woods can be pretty messy, with all of those leaves, branches, twigs and logs falling over and cluttering up the forest floor, making it hard to walk around.

What is Mother Nature thinking? Oh wait, now where does soil come from? Do these organic inputs actually help fuel the amazing and rich forest ecosystems we nurture, exploit, and enjoy?

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Douglas-fir log subject to fungal work in Eastern Washington (Photo: Ken Bevis)

According to U.S. Forest Service research, one acre of managed conifer forest in Washington averages around 107 tons of above-ground organic material at any given time (Campbell et al. 2010).  In the lush, west-side timberlands Douglas-fir and hemlock/spruce forests often contain 300-450 tons per acre, and this doesn’t even count what is below ground!

Photosynthesis and growth are continuously adding material to this system by pulling carbon dioxide out of the atmosphere and creating tissue through this amazing, miraculous process. This material continuously builds up, and we might wonder, why aren’t we simply overwhelmed with old tree and plant parts? A complex ecosystem under our feet breaks all of this material down and turns it back into basic components that recycle and feed the system.

Most of the essential break-down work is done by fungus. Yep, good old fungus.

In fact, the moist forests of the Pacific Northwest are a great kingdom of fungus, with enormous biomass of fungal life all around us. Kneel down and pull apart some of the forest duff and rotting wood. See the white threads of fungal mycelium down there? These tender “roots” are the main body of fungus, and move through the downed material, breaking it down to basic components using enzymes and other chemicals. The fungus uses some as food and nutrients, processes it again, and releases further broken-down material that is picked up by the next organism in the soil ecosystem.

There is a zone called the “rhizosphere,” which refers to the immediate area around roots and root tips, where a high degree of the biological activity in the soil occurs. Here, fungus, bacteria, nematodes, springtails, worms and many other organisms interact with each other and the plants to support the forest (Molina & Amaranthus, 1990). Sometimes, nitrogen (a limiting nutrient in soil) is pulled from the atmosphere and “fixed” by nodules of bacteria attached to the roots of plants, including alder. The alder doesn’t do it, the bacteria do. An amazing example of symbiosis.

It gets even more complicated …

There are also mycorrhizal fungi. They form an essential symbiotic relationship with plants by attaching to root systems with fungal hyphae (threadlike fungal “roots”). These help the plant by absorbing moisture and nutrients. In return, the fungus gets sugar from the plant’s photosynthesis. This is an amazing relationship that is being rigorously studied, and is now known to be critical element of a healthy forest.

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Mushrooms on the forest floor near Sequim, Washington. (Photo: Ken Bevis)

And don’t forget the mushrooms. Most of a fungus is in the form of hyphae, invisible above the ground, performing the quiet, unglamorous work of digesting organic material. But when conditions are right, the fungus needs to reproduce, mix genetics and spread their growth around, the mushrooms appear.

Mushrooms are the fruiting bodies of fungi. These can provide food for a variety of forest-dwelling animals, including the northern flying squirrel, which then spreads the spores through their droppings and help the fungus move about the forest.

Some of these above-ground fruiting bodies are tasty to us homo sapiens too, including chanterelles, matsutake, and morel mushrooms. Some fungi have below-ground fruiting bodies, such as truffles, but the effect is the same. These “fruits” are often meant to be eaten by something to help spread the fungal wealth in the ecosystem.

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Forest floor duff near Adna, Washington (Photo: Ken Bevis)

Fungi are the “engines of decay” in the forest ecosystem, beautifully described in David George Haskell’s excellent 2012 book, The Forest Unseen. Haskell looks closely at one square meter of a Tennessee forest over the course of a year, and shares observations of life, both large and small, that apply to forests everywhere.

Meanwhile, glamorous megafauna such as our banana slug, will eat fungal elements, including mushrooms, and can play their own role in breaking down organic material by shredding, eating, and defecating as they slide around the forest floor (see recent article in DNR’s Small Forest Landowner News).

There are a lot of other animal characters acting in the forest duff as well, including mites, millipedes, centipedes, springtails, protozoans, worms, spiders, snails and gophers. The food chain down there is stunningly elaborate, with fungus (and bacteria) in foundational roles, breaking leaves and wood down initially in a myriad of ways. Then small animals such as springtails, (some smaller than the period at the end of this sentence!) feed on the fungus and the released compounds. These critters are in turn fed upon by larger creatures such as millipedes, who are in turn fed upon by larger critters, such as shrews, who could be eaten by a small owl, who could be eaten by a larger owl or coyote, etc. It is boggling when the various energy pathways are identified.

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Forest floor megafauna – Red-backed salamander. (Photo: Ken Bevis)

Salamanders live in the decaying duff and wood of the forest floor. These ancient life forms live slow and deliberate lives, mostly in the dark tunnels underground, making dramatic appearances on wet days in our forests. They eat small insects and worms, and are the apex of the rotting wood food pyramid.

How our forests are managed can greatly influence what happens in the soil. The soils we began managing in the late 19th and 20th centuries were the products of many thousands of years of development by way of fire, ice, geology, organisms and time. Human impacts in forestlands today are generally in the form of changing vegetative structure, removing organic material and soil compaction.

What can small woodland owners do to help promote and protect the precious habitats and soil ecosystem below our feet? A few suggestions:

  1. Retain organic material across the land, especially decaying logs
  2. Keep portions of the land shaded to lessen soil drying
  3. Minimize compaction from machinery
  4. Scatter large organic pieces after harvest
  5. Retain patches of natural forest at regular intervals on managed landscapes to enable soil flora and fauna to persist and return to managed areas
  6. Get down on your hands and knees with a hand lens and marvel at the life in a patch of duff, rotting wood, and forest soil

 

This is only the proverbial tip of the soil ecosystem. I hope you got down low on the forest floor, looking under some duff with dirty hands after reading this article. Send me your photos, ideas and experiences!

Ken Bevis, Wildlife Biologist, Washington State Department of Natural Resources, ken.bevis@dnr.wa.gov

References

Campbell, S.; Addell, K.W.; Gray, A.; (2010). Washington’s forest resources, 2002-2006: Forest inventory and analysis report.  Gen. Tech. Rep. PNW-GTR-800.  Portland, OR: U.S. Department of Agricultur, Forest Service, Pacific Northwest Research Station.

Molina, Randy & Amaranthus, Michael. (1990). Rhizosphere biology: ecological linkages between soil processes, plant growth, and community dynamics.

Wasps in the Woods

By Melissa Fischer, Northeast Region forest health specialist, Washington State Department of Natural Resources, melissa.fischer@dnr.wa.gov

As many of you may have noticed, there were a lot of angry wasps flying about this past season. I was stung on multiple occasions while working in the woods.

I really thought I was going to get away with not stepping on a nest this year, but those hopes were dashed in late fall after I stepped on one over in Loomis State Forest. One of those stings left a welt unlike any I’ve had before (Image 1).

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Image 1. Welt on the back of my leg from a yellow jacket sting. (Photo: Melissa Fischer)

I am originally from Pennsylvania and was quite surprised at how aggressive the yellow jackets are here in Eastern Washington. I’ve been stung plenty of times in Pennsylvania, but not aggressively hunted in the woods as I am here. I also noticed that in some years (2015, 2018), yellow jackets seem more numerous and extra-aggressive. Wasps are not a focal insect for forest entomologists. I found myself curious as to why they are so aggressive some years and not others, so I decided to do a little research …

What are wasps?

Wasps are insects in the order Hymenoptera, which also consists of ants and bees. The wasps we will focus on are in the family Vespidae.

Sometimes people refer to wasps as bees, but they are not actually bees. Although the two have some similarities, they also have some significant differences. Some species of both wasps and bees are social; they live and work together, and both wasps and bees can be beneficial pollinators. Unlike bees, wasps are also predators and scavengers, killing pestiferous insects such as defoliating caterpillars and house flies.

Bees and wasps both consist of species that are capable of stinging. Only females sting though, as the stinger is actually a modified ovipositor (body part used to deposit eggs).

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Image 2. Morphological differences between wasps [Western yellow jacket (Vespula pensylvanica) on the left (Image: Buck et al. 2008)] and bees [sweat bee (Halictus farinosus) on right (Image: Top: Laurence Packer, 2014/ http://www.discoverlife.org and Bottom)
Although bees and wasps may have a similar morphological appearance, bees tend to be more hairy and stocky, whereas wasps are shiny, have much less hair, and have slimmer bodies with a petiole or “waist” (Image 2). Many species of wasp build paper nests from wood pulp; bees build their nests from a waxy substance. There are no wasp species that produce honey.

Yellow jackets

There are several species of wasp in Washington, the most aggressive of which are yellow jackets. Yellow jackets are about half an inch long, they are black and yellow, and feed on insects and sweet nectar. Although most people think of yellow jackets as one particular species, there are actually several, including the common (Vespula vulgaris), western (Vespula pensylvanica), aerial (Dolichovespula arenaria) and German (Vespula germanica) yellow jacket.

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Image 3. Four species of yellow jacket that can be found in eastern Washington; the common (Vespula vulgaris), western (Vespula pensylvanica), aerial (Dolichovespula arenaria) and German (Vespula germanica) yellow jacket (Images: Buck et al. 2008)

Aside from some morphological differences (Image 3), there are also some differences in the nesting habits of these yellow jacket species. The western and common yellow jacket build papery nests located underground. The aerial yellow jacket builds small, round papery nests above ground (Image 4). These nests are commonly located on roof overhangs and other protected exterior building surfaces.

The German yellow jacket, which was introduced into the northeastern U.S. in the 1970s and arrived in Washington in the 1980s, build above-ground nests as well, but they are not round, they are typically larger than that of the aerial yellow jacket, and they are often located within wall voids or attics.

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Image 4. Paper nest of the aerial yellow jacket (Dolichovespula arenaria) (Image: Buck et al. 2008)

Paper wasps

Similar to bees, paper wasps are often mistaken for yellow jackets. They are morphologically similar to yellow jackets with black and yellow coloration, very little hair, and slim bodies, but there are some noticeable differences.

Paper wasps tend to be slightly larger (about three-quarters of an inch long) and slimmer, and rather than black on the upper side of the antennae, they have orange (Image 5). Paper wasps fly with their legs hanging down, while yellow jackets tuck their legs against their bodies during flight.

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Image 5. Morphological differences between the western yellow jacket and the European paper wasp. Note that the upper side of the yellow jacket’s antennae is black and the paper wasps’ is orange.
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Image 6. Typical European paper wasp nest (Image: Buck et al 2008).

Two common paper wasps species in Eastern Washington include the golden paper wasp (Polistes aurifer), which is native, and the European paper wasp (Polistes dominula), which was introduced into the U.S. in 1981 and reached the Pacific Northwest by 1999.

Similar to yellow jackets, paper wasps are beneficial predators that also feed on nectar. They do not scavenge non-living food as yellow jackets do though. They make paper nests, but their nests are built so that the comb cells are open to view from below (Image 6). These nests are often found in protected sites such as under eaves, and typically contain 20 or fewer cells.

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Image 7A. Bald-faced hornet (Dolichovespula maculate) worker and B. typical bald-faced hornet nest (Images: Buck et al 2008).

Bald-faced Hornets

The bald-faced hornet (Dolichovespula maculate) is another common wasp species that occurs in Eastern Washington. The bald-faced hornet in not really a hornet; hornets are in the genus Vespa and none actually occur in Washington. Bald-faced hornets are about three-quarters of an inch long and black and white/pale yellow (Image 7A).

Bald-faced hornets build a large papery nest that may have leaves and twigs on the outer nest wall (Image 7B). They are considered beneficial, as they feed almost entirely on living insects, including yellow jackets.

The wasp lifecycle

In the winter, mated wasp queens overwinter in protected areas, such as under bark or on the ground in weedy areas. The paper wasp may overwinter in attics or other parts of buildings, and can become stinging pests when temperatures inside the house increase.

Wasp queens will emerge in the spring, beginning to feed on nectar and build new nests. (Old nests are not reused.) Yellow jackets and bald-faced hornets work as individual queens to construct their own nests. European paper wasps sometimes work together as cooperating queens to make a shared nest.

A single egg is deposited in each cell. The queen cares for her larvae by feeding them chewed-up insects. The larvae emerge as adult worker wasps about one month after eggs are laid. The workers are infertile females; males are not produced until September.

As summer progresses, the workers that are produced maintain the nest, forage for food, and tend to the larvae; the queen just lays eggs. Bald-faced hornets and some species of yellow jacket may have nests consisting of hundreds to thousands of workers by late August or early September. Paper wasp nests are substantially smaller, seldom exceeding 100 individuals and often comprising fewer than 20.

In the fall, new reproductive males and queens are produced. These reproductives leave the nest and mate. The old queen dies, and the colony begins to die out thereafter. All workers and males die with the first freezing temperatures.

Back to last summer … 

So what happened this past season? Why were there so many wasps? To start with, neither the Washington State Department of Natural Resources, nor the U.S. Forest Service (nor anyone else for that matter), release Vespidae wasps to control bark beetles or any other insect. Although wasps are beneficial predators, they are generalists and would not even begin to put a dent in the bark beetle population. On top of that, because bark beetles spend most of their lives under tree bark, they are largely inaccessible to Vespidae wasps.

There are many species of parasitoid wasps that are insect predators, some of which are specific to bark beetles. These wasps use their ovipositors as they were originally intended — to deposit eggs. Some parasitoids have very long ovipositors that allow them to deposit eggs under tree bark and into bark beetle tunnels. These eggs hatch into larvae that feed on bark beetle eggs, larvae, and sometimes adults.

Some species of parasitoid wasp deposit eggs inside insect larvae and feed on the larvae from the inside out. Others deposit eggs inside eggs, and the larvae feed on the eggs from the inside out. If you’ve ever wondered where people come up with alien scenarios in horror movies, you can look to parasitoid wasps!

Parasitoid wasps have been released for control of mostly invasive, nonnative insect species. One of the reasons nonnative species have the ability to become invasive is because they do not have natural enemies in their new habitat.

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Image 8.  The parasitic wasp, Agathis pumila, released for control of the larch casebearer (Image: Roger Ryan USFS PNW Station/ forestryimages.org).

If eradication of an invasive species does not work and other controls measures are not working, sometimes entomologists will look for native enemies (often parasitoids) of these invasive species in their home habitats. These natural enemies are collected and studied in quarantine labs. If, after many rigorous tests, they are found to be safe to release in the U.S., they may be released as biological control agents. A good example would be the release of Agathis pumila (Image 8) for control of the larch casebearer (Coleophora laricella).

Biological control agents are rarely released for control of native species because native species typically have a suite of natural enemies with which they have evolved.

So if DNR and U.S. Forest Service didn’t release the wasps, why were there so many? Insect populations in general are largely controlled by the weather, and wasps are no exception. Spring weather in particular largely determines if we will have wasp problems. Mild springs allow overwintering queens to survive, whereas cold, rainy weather may reduce the likelihood that queens can build a nest and collect enough food to feed her offspring.

Summer weather can also contribute to wasp issues because warm summer weather accelerates wasp metabolism and growth rates, resulting in more wasps at a faster rate.

Wasps become most troublesome in late summer and early fall as colonies reach their maximum size. Yellow jackets are more readily provoked into stinging during this time, as natural foods become scarce and workers aggressively scavenge food scraps. Additionally, workers are more likely to vigorously defend their nests as new reproductive queens and males are produced.

Protection/ Control

For general protection around the house, you may want to keep lids on trashcans, clean up fallen fruit, and avoid wearing perfume. You don’t want to leave soda cans and food laying around. Wearing white or tan clothes can be helpful, whereas mosquito and tick repellents are not, as they don’t work against wasps.

If you do happen upon a ground nest, run away!

Keep running until the wasps stop their pursuit. Yellow jackets may chase you several feet. Wasps can sting you approximately four or five times before they run out of venom (unlike honey bees which can only sting you once).

If any land on you, flick them off. Do not swat or crush their bodies, as this will prompt them to release alarm pheromones that then stimulates a mass attack from other workers.

Although yellow jackets traps do work to trap yellow jackets (they do not attract paper wasps or bald-faced hornets), remember that there is no way you will control the yellow jacket population using them. Workers may be flying from as far as 4,000 feet away, and there may be many nests with hundreds of wasps in the surrounding area.

Traps are mainly useful for drawing yellow jackets away from areas where people congregate. Therefore, if you do invest in one, hang it away from these areas.

Homemade traps can work rather well, too. One such trap consists of a container (such as an old dishwasher tub) filled with water and dish detergent and a board laid over top with a piece of meat hanging beneath the board. Yellow jackets will remove a piece of meat and try to fly away with it, but the meat will make them heavier than normal, causing them to fall into the water.  The detergent will act as a wetting agent, trapping the yellow jacket and making it unable to fly, leading to its death via drowning.

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Image 9. Banty rooster feeding on yellow jackets from a homemade yellow jacket trap.

I made one myself last year using fish skin for my bait. At first, I thought the trap didn’t work at all, as I was coming home from work and hardly any yellow jackets were in it.  But I quickly realized that one of my banty roosters was using it as his personal snack bar (Image 9).

Thereafter, I used vegetable oil instead of dish detergent as the wetting agent. I figured dish detergent may not be good for him. The vegetable oil seemed to work just as well.

If you need to destroy a nest, hiring a professional would be my first suggestion. If you choose to do it yourself, be sure to read the label of any insecticide you decide to use prior to treatment. Many are pyrethroids, nerve poisons that can be hazardous to humans, pets, and wildlife.

If you need to eradicate aerial nests, aerosol jet sprays and foam sprays are available. Dry dust insecticides would be best for German yellow jackets located in wall voids. For ground nests, use a liquid drench. Never use gasoline, as this will contaminate the soil and could contaminate ground water.

If you would prefer not to use insecticides in the soil, flooding a ground nest with water rarely works, but vacuuming can be effective (and should only done by a professional).

Treat nests after dark when flight activity is minimal. Do not shine a flash light directly at the nest. Spray the insecticide into the nest entrance first, then spray the nest surface, then soak the entire nest. Leave it for a day or two before removing, as any workers that were not in the nest may come back and come into contact with the insecticide.

Given the fact that wasps are ecologically beneficial, I would only use control if they are a direct threat. Pay attention to what species you are considering eradicating. While yellow jackets are indeed a rather aggressive species, bald-faced hornets are less so and paper wasps are actually quite docile (although both will sting to defend their nests).

Let’s all hope next season is less exciting in the world of wasps!

References

Akre, R.D. and Antonelli, A.L. 2003. Yellowjackets and Paper wasps. Revised by Peter Landolt and Arthur L. Antonelli.  Washington State University Cooperative Extension, EB0643. 7p.

Bechinski, E., Merickel, F., Stoltman, L. and Homan, H.  2009. Homeowner guide to Yellowjackets, Bald-faced Hornets, and Paper wasps.  University of Idaho Extension, BUL 852. 16p.

Buck, M., Marshall, S.A. and Cheung D.K.B. 2008. Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region. Canadian Journal of Arthropod Identification No. 5: 492 pp.   Available online at doi: 10.3752/cjai.2008.05

Bush, M.R. and Murray, T.A. 2014. The European Paper Wasp. Washington State University Extension Fact Sheet, FS152E. 5p.

Where’d That Big Hole Come From?  Creating Tree Cavities for Wildlife

The tiny screech owl looked out from a cavity in a cracked, hollow cottonwood tree near Yakima. It was amazing how cryptic the bird was. I wouldn’t have noticed it if I had not been looking up, admiring the gnarly stem of that big old tree. That cottonwood, with broken branches and a rotten core was a great example of a “Wildlife Tree”.

Wildlife Trees can refer to those with some sort of “defect” allowing animals to get inside and use the central portions of  tree stems as secure habitat for nesting, roosting, or denning. These are crucial habitat for about 40% of our forest species in Washington. The solid woody cylinder that makes up a tree bole is usually unavailable as habitat for the numerous species that utilize cavities. These critters include small mammals such as bats, insects such as wasps and bees, numerous birds including owls and the iconic wood duck, and larger mammals like raccoons or black bears who can den in hollow trees.

These cavities only exist when certain conditions occur. First, a tree has to grow large enough to provide the woody mass needed for a cavity large enough for the species. Then, something must happen to subsequently hollow it out and create the space within the wood. Random events, such as weather related broken tops, followed by heart rot infestation, or pre-existing heart rot in a main stem (say, for example, in a large cedar) followed by a branch breaking off, (then more rot and insects) could create these cavities. However, these events are generally rare in the forest and are less likely in managed forest settings, as we tend to remove dead and “defective” trees from our stands.

And then there are woodpeckers. These keystone species create cavities as a regular part of nesting and courtship behavior, carving perfect and appropriate hollows in rotten stems to meet their needs. They leave some cavities behind as they make new ones each year to meet their biological imperative. They need standing dead wood that has been dead long enough to get soft enough for the woodpeckers to dig it. These types of standing dead trees can be rare but hold great habitat value.

Humans can make cavities too, using arborist techniques of climbing and creative chainsaw work to hollow out stems for wildlife to use.  I had a recent opportunity to visit past Wildlife Tree work and inspect the outcomes after 12 years.

In 2006, wildlife tree creation pioneer and expert, Tim Brown of Snoqualmie, WA, worked with the U.S. Army, U.S. Forest Service Research Lab, and the Nature Conservancy on Fort Lewis (near Olympia, WA) to create cavities. This work had the goal of providing habitat for nesting wood ducks, Western gray squirrels, pollinators and other wildlife. Earlier this summer, (June 2018), we returned to look at these cavities to assess what sort of use had occurred. Tim climbed up to some of these old cavities and looked inside.

What we found was fascinating: Nesting material was present in every single cavity examined, along with eggshells, indicating successful hatching of wood ducks. One had a failed clutch of 3 wood duck eggs (we examined them and determined they had been in the cavity for a long time and were dead). Others had evidence of mammal use (squirrel) and yet another had a colony of honeybees.  All inspected cavities were intact and functioning.

Creating the cavities is relatively straight forward, but highly skilled tree climbing and chainsaw work is necessary. A shallow section of the tree, perpendicular to the up-down axis, (a face plate – see photo) is cut on the tree surface, removed and lowered carefully to the ground. Then, a saw is used to hollow out an appropriate sized cavity in the tree (approximately 12” x 12” x 18”) mimicking a pileated woodpecker cavity. An opening is cut into the faceplate of about 3” or 4” in diameter, at an appropriate height from cavity bottom. Then, this cavity cover is returned to the hole and attached with nails or screws. Simple, and it works as we observed on Fort Lewis.

Location is important. Brown cut these cavities into open faces of large trees facing small lakes and wetlands on Fort Lewis, seeking optimal positioning for the wood ducks and other wildlife. Tim pointed out that cedars are preferred due to their ability to grow over the wounds, thus sealing the edges of the cavity faceplate. Several of these cavities had marvelous healing evidence over the carved entrance holes.I asked Tim Brown some questions about this work:

What sort of wildlife were you hoping to attract? 

“The project was aimed at all species that use cavities, including wood ducks, small owls, squirrels, bats, and all of the other animals that use cavities. I’ve seen them get lots of use over many years and they can really last a long time. The best cavity is one that outlives you.”

What sort of trees are best for cavities?  
“Cedar families are the best, as they heal over and the trees can live for centuries. True and Douglas firs are ok too, if cedars aren’t available. Some hardwoods are okay, but they often don’t last as long.”

How long have you been doing this sort of work?
“I started making wildlife trees over 40 years ago. I’ve worked all over North America, including Canada. I love doing this work and seeing how it helps wildlife.”

You can call Tim at (206) 271-2020 to talk about his copyrighted work. The substantial value of these wildlife trees as habitat cannot be overstated. Practitioners now make habitat trees all across North America, and many of these techniques originated and were refined in the Pacific Northwest by Tim Brown.

If you have questions or stories about creating or protecting wildlife trees on your own forest property, please send some pictures and stories to: ken.bevis@dnr.wa.gov Thanks! And keep on protecting wildlife trees!

Ken Bevis, Stewardship Biologist, Washington Department of Natural Resources, ken.bevis@dnr.wa.gov

Fishers in Managed Woodlands of Western Washington

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Fisher. Photo. John Jacobsen/Wash. Dept. of Fish and Wildlife.

Predators. The word conjures up visions of fierce cougars or grizzly bears sneaking around in the dark looking for human-sized prey animals. But what about the more diminutive predators, such as fishers, that eat small mammals, fish and birds?

Fishers are members of the family Mustelidae, which also includes weasels, marten, mink, otter, wolverine and several other predators. These are a remarkable assemblage of similarly built critters: short legs, sharp eyes and teeth, highly sensitive noses and explosive speed and agility. They are adept at catching many different prey species, from shrews, mice and birds to fish and, in the case of wolverines, deer. They also a diverse lot with many different lifestyles that can include climbing trees, skittering through forest undergrowth, cruising high mountain snow fields, burrowing underground or rapidly swimming after prey.

Fishers are a unique forest-dwelling mustelid. They are a medium-sized weasel, about the size of a house cat. They are a rich chocolate-dark brown in color and reside in low- to mid-elevation forest habitats. With a body length of about 36” include tail, and weighing between 8 and 10 pounds, fishers are slightly larger than marten, which tend to live at higher elevations.

Fishers disappeared from Washington forests decades ago due to overharvesting for their fur, habitat destruction and their vulnerability to trapping (weasels are suckers for a good scent lure). After wildlife surveys in the 1990s and early 2000s detected no fishers in Washington, a state recovery plan identified the need to reintroduce these animals to the state.

In 2008, the Washington Department of Fish and Wildlife (WDFW), US Geologic Survey, Conservation Northwest, British Columbia Ministry of Environment and National Park Service combined efforts to organize a fisher reintroduction release in Olympic National Park. Another set of releases in the South Cascades began in the fall of 2015. All of the released animals were relocated from British Columbia in cooperation with the BC Trappers Association. In 2017, reproduction was documented near Mount Rainier National Park. It is shaping up to be a remarkable success story!

Habitat and Needs

Fishers need forested habitats with a rich understory, snags and down logs to support the small mammal populations they prey upon. Fortunately, managed woodlands can provide all of these habitat features.

fisher habitat in western Washington
Excellent fisher habitat in western Washington.  Photo: John Jacobsen/Wash. Dept. of Fish and Wildlife

It is hoped that successful reintroduction of the fisher to Washington state will result in sustainable populations across the landscape. Because managed forests are capable of providing suitable fisher habitat, small forest landowners on the west slopes of the Cascades have a direct interest in learning about the habitat needs of this amazing animal. To encourage landowners to take part in assisting the success of this species, the US Fish and Wildlife Service, in cooperation with WDFW, offers a program in which landowners agree to protect fishers on their lands. In return, the landowner receives protection from any future land use restrictions that could result from the presence of fishers. This arrangement, a Candidate Conservation Agreement with Assurance (CCAA), is straightforward and many landowners, large and small, have already signed on. Click here for more information on the CCAA program.

Fishers are no threat to normal workings of family forest lands (unless you happen to be a mouse, squirrel or chicken!) and they can provide a natural control over damaging rodents in tree farms. Returning this animal to our ecosystem will restore some of the remarkable richness of Washington’s forests.

For more information on the fisher and CCAAs, please visit the WDFW website, or contact Gary Bell at (360) 902-2412.

And as always, feel free to contact me with your questions, stories or photos of wildlife on your forested woodland.

by Ken Bevis, DNR Stewardship Wildlife Biologist, Ken.Bevis@dnr.wa.gov