I take my dog for a walk almost everyday, usually to a chunk of BLM land on the east side of town. The city and BLM have created a small recreation area there, with many trails winding up and around a mountain. The trails are in a stand of big sage, an ancient stand where sage, bitterbrush, Mormon tea, saltbush, and desert peach are thick and tall. With each walk, I become more enchanted with the subtle complexity of this unique ecosystem.
I see an old growth forest as I walk among these tall shrubs, even though there are only a few scattered pinyon pines on the hillsides. Because if you bend down and look close, there is an entire universe in and among these shrubs. Rabbits, jackrabbits, and squirrels create paths connecting one patch to the next. Small openings among the branches become rabbit forms – resting spots out of sight from their predators like golden eagles and coyotes. Kangaroo rat holes are scattered around, and piles of clipped sage branches indicate where the jackrabbits and cottontails have been feeding. Lizards and snakes find their way among the bushes. In all, some 350 species call the sage steppe home, with several species, including sagebrush obligates such as greater sage-grouse, pygmy rabbits, sagebrush voles, Brewer’s sparrows, sagebrush sparrows, and sage thrashers living or breeding only in sagebrush habitats. Sage-grouse and pygmy rabbits feed on sagebrush, while it provides important nesting habitat for Brewer’s sparrows, sagebrush sparrows, and sage thrashers. Sagebrush is important winter habitat and forage for elk, mule deer, and pronghorn.
On my walks with the dog, I am happily entertained by the beautiful songs of the birds nesting in the sage. During our walks, we are heralded by Brewer’s sparrows, black-throated sparrows, mockingbirds, and spotted towhees. Unfortunately, the freeway is too close to permit decent recording, so I drive out toward the center of the state to try to find relatively undisturbed patches of sagebrush in which to record.
In early June, the dog and I took a road trip across the center of Nevada and on to the far northeastern corner then crossed into Idaho. The first night we spent in a small mountain range SW of Austin. We got there just before sunset and camped in a small flat surrounded by sagebrush, where Brewer’s sparrows, meadowlarks, and horned larks were singing the sun down. It was a bit breezy, but I set up the mics hoping to catch a nice dawn chorus. As I wandered through the sage, I noticed something interesting. Although there was a gusty breeze blowing, the sage made no sound. Even with my ear right next to the sagebrush, it took a strong gust to create any wind noise through the branches. The many fine leaves of the sage, covered with a very fine fur, effectively dampened the sound.
I woke up around midnight to find the clouds from the afternoon thunderstorm had completely disappeared and the milky way was putting on a nice show. So I took some photos, appreciating how dark the skies are over much of the Great Basin.
As I was setting up the camera, I started hearing a strange snoring sound. I was awake, Shadow was awake, no one else was within 10 miles, so it could only be – frogs! I took a few photos, put the camera gear away, and grabbed my parabolic dish and recorder and went and tracked the frogs down. They were calling from a nearby stream (that’s desert-speak for a small trickle of water). The noise of the stream and some wind buffeting made for poor recording. When I got back to the car, I turned on the recorder I had attached to my soundscape mics, and could actually hear the frogs better. As I settled back in my sleeping bag, being lulled to sleep by the soft snoring of the Great Basin spadefoots, a small group of coyotes chimed in:
The dawn chorus, although a bit distant, was lively and I managed to record not only the horned larks, meadowlarks, and Brewer’s sparrows of the night before, but also sagebrush sparrows, chukar, and nighthawks:
Unfortunately, the distant stream overwhelmed the recording a bit. That’s usually not a problem in the desert, but it was a wet winter which extended into early June. I had to alter my trip some due to roads being impassable either due to mud or snow.
Big sagebrush (Artemisia tridentata) is common throughout the Great Basin, and is one of the indicator species of the Great Basin desert. It seldom occurs alone; local soil conditions, temperature, and moisture help determine its companions, which range from grasses to trees. Through much of the Great Basin it exists in stands of shrubs, anywhere from 1 to 8 feet tall; miles and miles of grey-green expanse without a tree in sight. It’s hard to imagine as one drives through this seemingly endless expanse of shrubland both how complex and how fragile it is. Although common at the moment, sage-steppe ecosystems are disappearing at an incredibly rapid rate; so fast that they are considered one of the most endangered ecosystems in the country. Hundreds of thousands of acres are lost every year to fire. Big sage and most of its companions are not fire tolerant, and are easily killed by fire. Burned areas are often quickly reseeded by cheatgrass (Bromus tectorum), an exotic grass that spreads quickly and loves disturbed areas. Native to Eurasia and north Africa, it was introduced to the US in the mid-1800’s, and easily hitched its way across the country. It really likes the Great Basin. It gets established by soil disturbance including grazing, road maintenance, off-road travel, construction related to energy development, and anything else that mangles the cryptobiotic crust (a microscopic mat of fungi, algae, bacteria, and mosses that cover the ground). Once established, it changes the fire regime, which is particularly devastating in sagebrush ecosystems.
Unlike many of the western forests, which are not only fire-tolerant but often fire-dependent (they need fire to spread their seeds), sagebrush is destroyed by fire. Fire is a natural part of the ecosystem, but the fire frequency in this ecosystem, prior to the arrival of cheatgrass, was on the order of 50-400 years or more. It can take decades for sagebrush to reestablish following a fire, and may take a hundred years or more to develop a mature stand. With cheatgrass so prevalent in the area, now when part of the sage-steppe ecosystem burns, it is quickly filled in by cheatgrass. Dry cheatgrass is very flammable, and any spark can set it off, whether from a bullet ricochet or the heat from a catalytic converter. Cheatgrass burns fast and often, and can keep the sage-steppe ecosystem from reestablishing. Next time you drive across Nevada on Interstate 80, notice the large patches of grass covering the hillsides. Those are areas where the sagebrush has been replaced by cheatgrass.
For an interesting article on this issue, which includes a nice map of fire scars in the Great Basin, see here.
So I have a mission now. To try to document the voices of the sage-steppe before it disappears. The voices differ in different parts of the Great Basin: the voices I hear on my morning walks are not the same as those in central or eastern Nevada. So you’ll find me out poking around the sage-steppe. Just listening.