Autumn Comes To The Desert
If you live where the skies are dark you notice it first in the constellations. The summer stars begin to shift out of view, rising four minutes earlier each day until they spend most of their time shining vainly through blue daylit sky, and winter constellations like Taurus, the Pleiades, and Orion start to make their way through the night sky. But you don't have to recognize any constellations to detect the shift in seasons: you just have to notice that all of a sudden you're seeing them on your way home from work.
Winter nights are long in the desert, just like they are elsewhere outside the tropics, and autumn provides a warmup. California's desert cools off this time of year. Before long nighttime temperatures may reach freezing. But we're also heading into the time of year when water is most reliably available, and available water means more chance to grow. So unlike other places where Nature uses autumn to prepare for being mostly shut down in winter, autumn in the California deserts is a complex dance of some things waking up and others going to sleep.
It's warm during the day, still, even in the High Desert, but there have been enough cold nights that lizards and snakes have gotten scarce. Venturing out means a reptile is more likely to find a roadrunner or other predator trying to fatten up for the cold months. A cold night means more time spent trying to warm up in the sun, which means more time exposed and vulnerably sluggish. Smaller lizards' food supply -- insects and other invertebrates -- have dried up anyway, at least above 3,000 feet or so. As packrats and deermice spend fewer night hours abroad, hunting goes south for snakes as well. This is the time of year when snakes start to decide not to get out of bed on cold mornings, much to the relief of rattler-shy hikers. The cold half of the year isn't snake-free: you can find rattlesnakes active in the desert at any time of the year if the daytime temperature's above 70° or so. I've seen one or two on warm afternoons in January. But for the most part, that spine-chilling rattle gets less frequent this time of year.
Animals that stay active after summer ends are working hard to fatten up. The Audubon's cottontail rabbits near Joshua Tree National Park have grown sleek in recent weeks. Coyote song rings out each night as one rabbit or another is harvested. Rabbits stay active throughout the winter rainy season, in part because that's when the best rabbit food is available: the just-sprouted annual plants and new flush of growth on desert shrubs. During the summer they tend to hunker, emerging from the shelter of a shrub or den mainly at dusk and dawn. These days it's more common to see them abroad at noon. Cottontails don't have to have access to water to survive, as they can create it by metabolizing their food. But unlike the kangaroo rat, which is probably the desert mammal that can turn food into water most efficiently, cottontails will drink water if it's available. I have a dish of water in our yard that I refill every day, and each morning this week as I've stumbled into the kitchen to make coffee a cottontail or two have been quietly lapping up the Joshua Tree tap water there.
Gambel's quail are kind of the bird equivalents of rabbits around here: plant eaters that breed abundantly and are regularly eaten. This week it's clear the local quail are thinking about making their next generation of chicks. The last batch are either grown to maturity or long-eaten, and quail that stuck to mated pairs all summer are now massing in coveys of two or three dozen. I throw a few hands full of sunflower seeds to them each morning, and even when they were paired off they'd assemble to come clean every last seed from the ground. Now, though, the males spend more time squabbling than eating. A male will venture too close to a female who's been spoken for, and her mate will drop the seed he's been eating and chase the interloper for twenty feet or so. Or males will square off, stand on tiptoe, jut out their breasts at each other and flap their wings violently. The females attend to eating: they have the harder job looming, what with the impending laying. More food eaten now means more fat and protein and calcium to make eggs with.
In a few weeks we'll see the pairs split off from the covey again, and then little families with mom and dad and a line of tiny quail behind them, the babies disappearing one by one. The roadrunner will be far less welcome in the yard. Now he ambles past the quail mostly unmolested. The last time there were juvenile quail about, the males treed the roadrunner every day, keeping him away from their offspring.
If the winter rains start soon, and perhaps even lead to a few days of snow, the Joshua trees will start showing odd changes in another two months. The buds at the ends of the branches are usually set to grow a new year's crop of dagger-like leaves. But if the winter is wet enough, a few will undergo a little-understood shift thought to be triggered in part by a combination of moisture and temperature. They will change from leaf buds into flower buds. In late winter they will add spires of pale cream-colored blossoms to the trees' outlines.
If winter rains come to the High Desert soon, before the temperatures drop, we may see a second season of bloom, including a repeat of some spring flowers like sand verbena and Mojave aster, and perhaps a few that bloom only in the fall. If cold comes before the rains, the Mojave's floral color will tend toward deep rust-red: the dried, inflated stems of desert trumpet, the spent blooms of California buckwheat, the stems and leaves of invasive red brome grass. They give a sense of autumn to the desert that even the most recently transplanted Easterner will understand.
Chris Clarke is an environmental writer of two decades standing. Director of Desert Biodiversity, he writes from Joshua Tree regularly at his acclaimed blog Coyote Crossing and comments on desert issues on KCET weekly. Read his recent posts here.