This is a blog about the native conifers of the Pacific Northwest. It is a companion to the Northwest Conifers site. The blog will focus on timely and interesting details about our conifers, their connections to the rest of the environment, and our connection to them.

Thursday, October 22, 2020

Douglas Squirrel

Walking in the conifer forests of the Pacific Northwest is always a visual feast, with so many tall, awe-inspiring trees and an enchanting understory of diverse shrubs and wildflowers. However, you will miss a wonderful part of the experience unless you are quiet and listen. You can hear a chorus of various bird calls and songs. However, one of the most intriguing calls is not from a bird at all. It is the melodic call of the Douglas squirrel.

The most frequent Douglas squirrel call is similar to the call of a flicker. It is a short burst of high frequency that quickly drops in frequency and volume: “Chee-you.” This call is a warning that a predator is nearby. Maybe the squirrel has spotted you. When really excited, it gives a rapid sequence of just “chee chee chee chee” sounds. The other sound you will often hear is a long, continuous “cheecheecheecheechee.” This is the Douglas squirrel’s intruder alert. These squirrels are territorial and will defend the area around their nest and food cache. Perhaps it doesn’t have a large vocabulary, but this string of loud squirrel profanity would give any intruder pause. If you surprise a Douglas squirrel on the ground, it may make an excited combination of variable sounds as it scampers up a tree. You can hear the different sounds here

Other sounds to listen for: The scurrying of little squirrel feet scampering up a tree trunk. Also, if you hear the sound of cones hitting the ground, chances are, there is a Douglas squirrel dropping them from the top of a nearby tree.

The Douglas squirrel is a small squirrel native to the conifer forests of the Pacific Northwest. In summer, it is brown on top and orange underneath with a dark stripe on the side between the top and bottom colors. In winter, the top is darker, and the color below turns light gray. The dark stripe on the side fades in winter. The Douglas squirrel is about 12 inches long, including its bushy tail, much smaller than the western gray squirrel, and somewhat smaller than the two non-native squirrels often seen in urban areas: the eastern gray squirrel and the fox squirrel.

What the Douglas squirrel lacks in size, it makes up in energy and personality. It races up and down trees, takes flying leaps from branch to branch and tree to tree. Even when it is still, it appears and sounds like a concentration of suppressed energy, calling and flicking its tail. It is these birdlike calls that distinguishes the Douglas squirrel from the larger squirrels. Their calls sound like the unremarkable bark of a tiny dog.

The favorite game of the Douglas squirrel is the chase. Juveniles start playing this game as soon as they can be out of the nest, chasing each other up, down and around tree trunks, leaping from branch to branch. It is good training for the adult chase, which takes two forms. One is the intruder chase, which starts when an intruder ignores the loud intruder call. The other is when a female leads a male on a mating chase.

The Douglas squirrel was a favorite of John Muir. He devoted an entire chapter to this squirrel in “The Mountains of California.” He wrote that the Douglas squirrel

… threads the tasseled branches of the pines, stirring their needles like a rustling breeze; now shooting across openings in arrowy lines; now launching in curves, glinting deftly from side to side in sudden zigzags, and swirling in giddy loops and spirals around the knotty trunks; getting into what seem to be the most impossible situations without sense of danger; now on his haunches, now on his head; yet ever graceful, and punctuating his most irrepressible outbursts of energy with little dots and dashes of perfect repose. He is, without exception, the wildest animal I ever saw….

Douglas squirrels like mature forests with cone bearing conifers. The seeds inside the cones are their primary food. A squirrel will get a cone, sit on a branch, deftly strip the scales, and eat the seeds inside. In about two minutes, the squirrel will be finished and drop the stripped cone core. The squirrels often have a favorite spot for stripping cones, creating a large mound or midden of cone scales below. Look for the tiny “cone cobs” in the midden.

A squirrel strips a cone, asks, "You looking at me?" And is off in a streak.

Douglas squirrels also eat fungi, and the seeds from maples and other broadleaf trees. In the spring they feast on the tender new growth from a great number of trees, including flowers, pollen cones, and conifer needles.

Douglas squirrels do not hibernate. They must store food for winter. When they drop cones on the ground, they will come down and carry them off to a hidden cache, usually under a log or some other damp place. They do this in late summer or fall after the cones are mature, but before they open and disperse the seeds. Timing is critical. They must wait until the seeds inside are fully developed. And storing cones with no seeds is, well, just pointless.

The scientific name of the Douglas squirrel is Tamiasciurus douglasii, both named after David Douglas. It is native to the forests of western Washington and Oregon. It also lives in southwest British Columbia and northern California. Its cousin, the American red squirrel (Tamiasciurus hudsonicus) is widely distributed across the rest of North America wherever conifer forests grow, including eastern Washington and northeast Oregon. Both species are sometimes called pine squirrels or chickarees. Although the range of the two species does not overlap, curiously, the red squirrel lives on Vancouver Island, while the Douglas squirrel populates the coast of mainland British Columbia.

Be sure to listen for these squirrels when you are hiking in the woods. If you hear one high in a tree overhead, sit down and wait. It may come down for a closer look, and possibly give you a sharp burst of squirrel profanity for invading its space.


More info

Sunday, October 4, 2020

Focus on Whitebark Pine

Whitebark pine is a perfectly adapted alpine tree. It grows at or near the timberline throughout the mountains of the Pacific Northwest. Since it doesn’t compete well with other conifers in wet or shady locations or on north facing slopes, you will find it in open, dry and sunny locations on ridgetops or south facing slopes.  Whitebark pine is the only stone pine that grows in North America. The stone pines have large wingless seeds. Other stone pines grow in Europe, China and Korea. These edible seeds are called “pine nuts,” which you can buy in grocery stores if you can afford them.

You can identify whitebark pine by counting the number of needles in each bundle. Whitebark pine needles grow in bundles of five. Western white pine also has 5 needles per bundle, so it’s easy to confuse it with whitebark pine. However, if you see any cones, and can tell eggs from bananas, it’s easy to tell them apart. Whitebark cones are about the size and shape of eggs, while western white pine cones are about the size and shape of bananas.

The most remarkable thing about Whitebark pine is its relationship to the Clark’s nutcracker. Unlike the cones of most other native pines in the Northwest, which open and disperse their winged seeds, white bark pine cones remain on the tree and do not open when they mature. This is where the eating habits of the Clark's nutcracker play an essential role in the life cycle of the Whitebark pine. These birds easily pull apart the cones to get the seeds and bury them in the ground for eating later. Or perhaps they fancy themselves as tree planters. It’s just that they often get hungry and return to eat some of the seeds. In either case, they don’t eat all of the seeds they “plant,” so some of them germinate and continue the life cycle of the pines. This paradigm case of mutualism benefits both the nutcrackers and the whitebark pines. However, nutcrackers don’t get all of the whitebark seeds. They are also a favorite of Steller’s jays, Douglas squirrels, golden-mantled squirrels and chipmunks.

By the way, the feeding habit of nutcrackers is why you seldom find any whitebark pine cones on the ground, just cone fragments left by the nutcrackers. This can make it more difficult to tell a whitebark pine from a western white pine. If you are at the timberline, it’s probably a whitebark. If it’s a small tree, it may not be producing cones yet, so good luck. Looking at the needles may help. Whitebark needles are green, while western white pine needles are blue-green.

The scientific name of whitebark pine is Pinus albicaulis. The common and scientific names describe the whitebark pine. Albicaulis means "white stemmed." To remember the name, think of it as the "Albino-bark Pine." Other common names: Pitch pine, scrub pine, and creeping pine. John Muir called it "Dwarf Pine."

If you go looking for whitebark pine, you may be disappointed. Like other white pines, whitebark pine has been decimated by white pine blister rust. You can see their ghostly, white forms still standing in large areas, for example, above Mount Hood Meadows. White pine blister rust is a disease caused by an Asian fungus, which was introduced to North America over 100 years ago. It has caused serious damage to the white pines all across the U.S. In the Northwest, white pine blister rust has infected large areas of whitebark pine. The fungus first attacks the needle, then the branches, and eventually the trunk of the tree.

Whitebark pines tested for resistance to blister rust.
Some survive, others, not so much.

White pine blister rust has a fascinating life history. It requires two host species to complete its life cycle. One is a white pine. The other can be a variety of plants from the Ribes genus, locally, usually shrubs like currants and gooseberries. The infected shrubs infect the trees, and the trees in turn infect more shrubs. If you remove one of the hosts, the fungus cannot reproduce. Years ago, the Forest Service sent out summer workers to clear affected areas of the shrubs necessary to complete the life cycle of the fungus. Unsurprisingly, that effort failed. More recently, efforts have been underway to develop genetic strains of whitebark pine that are resistant to the disease. For details on this effort, see this post on the Dorena Genetic Resource Center

Whitebark pines just don’t seem to be able to catch a break. Recently, the mountain pine beetle has attacked large areas of whitebark pine. More outbreaks are likely as winters become warmer allowing pine beetles to survive in areas where they were once killed by cold winters. Due to the decline in whitebark pine from blister rust and beetles, it is now listed as an endangered species on the IUCN Red List. Climate change may prove to be the biggest challenge to the survival of whitebark pine.

Whitebark pines may need our help to survive the assault of these enemies. They are an important member of the alpine ecosystem, providing food for nutcrackers and shelter to other birds and mammals, and contributing to the beauty of the high mountain environment. We can help them survive by supporting efforts to combat blister rust, and by reducing greenhouse gas emissions.

If you want to see some whitebark pines, here are some locations that are easy to get to: Above Timberline Lodge on Mount Hood, on the rim above Crater Lake, and at the top of the Mount Howard tram at Wallowa Lake.


More info

Northwest Conifers: Whitebark Pine  

Gymnosperm Database: Pinus albicaulis 

Our Threatened Timberlines: The Plight of Whitebark Pine Ecosystems  

Sunday, September 20, 2020

Focus on Western White Pine

Western white pine doesn’t have the charm and stature of ponderosa pine with its golden bark and lofty height, but this white pine does have many subtle, attractive qualities. It grows straight and tall when given a chance, sometimes to a height of nearly 200 feet. The needles grow in bundles of five and have a blue-green color. The cones have a distinctive banana shape and are longer than any other Northwestern conifer except sugar pine cones. The gray bark breaks into rectangular plates on large trees. Another distinctive feature is the sticky resin on the cone scales. You will often see cones on the ground under a western white pine, and if you pick one up, don’t be surprised if you have sticky fingers. You were warned.

The scientific name of western white pine is
Pinus monticola, named by David Douglas after he found it growing on Mount St. Helens. The species name is Latin for “mountain dweller,” and that is where you can find it, growing throughout the mountains of the Pacific Northwest. It grows in the Cascades and in the Coast Range at elevations of 3000 to 5000 feet. In Washington and British Columbia, it grows right down to sea level. It also grows in northeast corners of Oregon and Washington, and in northern Idaho. It is the state tree of Idaho, where it’s sometimes called “Idaho pine.” In California, it grows in the Siskiyous and Sierras.

You may be surprised to find western white pines growing in the Coast Range of Oregon, but you can find some in the higher elevations. Some young ones grow in the Tillamook Forest near the top of the Storey Burn Trail, west of Storey Burn Road. In Portland, you can see several large western white pines at Hoyt Arboretum. They are growing along the Bristlecone Pine Trail. They are easy to identify by the labels on the trees and the banana-shaped cones on the ground. Again, don’t pick them up if you don’t want sticky fingers.

Western white pine was once abundant in its range, but disease and logging have greatly reduced its numbers. As with many other white pines, the bane of western white pine is white pine blister rust, a fungus introduced in North America from Europe over 100 years ago. Although the extensive stands of western white pine have been decimated by blister rust, the species has developed some resistance to the disease, and the Forest Service has a program for breeding rust-resistant trees. For more information, look here. Bark beetles also attack western white pine, especially after they have been weakened by blister rust.

Western white pine wood is described as nonresinous — no surprise, since it seems to send all that sticky resin to the cones. The wood is soft, straight and stable in character, which make it desirable for making moldings and window and door frames. The wood is light, attractive, and easy to work, making it ideal for wood carving. In the past, it was the primary source of match sticks.

Pollen cones

There appear to be few genetic differences between western white pines in different locations in the Pacific Northwest. So you can collect seeds from one habitat or elevation and successfully grow them elsewhere. The trees can readily adapt to different growing conditions. However, California populations do seem to be genetically distinct from those in the Northwest. The California trees are more resistant to white pine blister rust.


More info

Northwest Conifers
Gymnosperm Database 
USDA: Silvics of North America
Coniferous Forest