Western Scrub Jays Replant the Desert One Acorn at a Time

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Western scrub jay | Photo: Matt Knoth/Flickr/Creative Commons License

Fire is hard on the desert. Many desert plants, the Joshua tree among them, don't recover quickly from burns. But as more time elapses since one catastrophic wildfire in the California desert, the scorched landscape it left behind may just be doing something like recovering... with some important help.

We really won't know what the long-term effects of wildfire are on a typical desert landscape for perhaps a century, perhaps longer. It's only been a few years — six in July — since the Sawtooth Complex Fire, named for a striking small range of mountains near Pioneertown, immolated 61,700 acres in the hills above Yucca Valley. That's hardly enough time to survey the extent of the damage, much less to expect the burned desert to heal itself. And if the desert does heal, it's likely to be quite different from what was there before the fire.

July 2006 would have been a bad month for the environs of Joshua Tree National Park even without the Sawtooth Complex fire. Burns in the Covington Flat area of the park ate up about 1,500 acres of desert wildland in that same month. But the Sawtooth Complex Fire, sparked July 9 by lightning strikes, dwarfed them. By the time the Sawtooth merged with the Millard Complex Fire on July 14, burning northward out of the San Gorgonio Wilderness, the two had burned over 80,000 acres — more than half the area of 2009's catastrophic Station Fire. The economic damage was considerable, with more than 50 residences and 200 vehicles destroyed. One person, Jerry Guthrie of Pioneertown, died in the fire — as did countless wild animals.

This video, taken by firefighter Dominic Pulsipher at the intersection of Pipes Canyon and Pioneertown roads, shows the frightening aggressiveness of the fire in its early days:

Hiking up Pipes Canyon one can still see abundant evidence of the fire. A funereal forest of blackened snags lines both north and south slopes of the canyon, the remains of piñon pines and California junipers, and perhaps a few other tree species. Burned Joshua trees, still holding their dead leaves six years later, strike stark poses against a clear desert sky.

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Dead Joshua trees | Chris Clarke photo

There are no pines or junipers here anymore, or at least if they are they're well hidden. The largest trees are growing in the wet canyon floor: willows and the unrelated "desert willow," among others. Uphill, things are still a bit sparser. Young shrubs have grown up among the charcoal snags on the slopes, their leaves a slightly incongruous dark green.

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South slope of Pipes Canyon | Chris Clarke photo

They're desert scrub oaks, with the ungainly Latinate name Quercus cornelius-mulleri, named for an eminent California botanist. They were abundant here before the fire; they're abundant again. They're all over here, ranging about four feet tall and as wide, occasionally seeming to grow out of the skeleton of an older scrub oak.

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Quercus cornelius-mulleri | Chris Clarke photo

This canyon is managed as a natural preserve by the Wildlands Conservancy, and Conservancy staff have spent a few years attempting to nudge Nature along in restoring the landscape — transplanting a yucca here and there, trucking in supplemental water to irrigate the plantings. But the new crop of native oaks was planted by a different team of gardeners.

Western scrub jays, Aphelocoma californica, are birds in the crow family that range from western Washington state to Texas, and south into Mexico. They are among the smartest of vertebrates. They seem to consciously plan for the future, a trait shared only by humans and not all of us at that. Scrub jays cache food — they hide it in secret spots throughout their territory — and can not only remember the locations of 200 or more distinct caches, but what kind of food is in those caches, whether it's perishable or not, and who watched them cache it. In a study published two months before the Sawtooth Fire, researchers noted some of the intricacies of scrub jay planning:

Western scrub-jays hide food caches for future consumption, steal others' caches, and engage in tactics to minimize the chance that their own caches will be stolen. We show that scrub-jays remember which individual watched them during particular caching events and alter their recaching behavior accordingly. We found no evidence to suggest that a storer's use of cache protection tactics is cued by the observer's behavior.
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Western scrub jay | Photo: Amit Kotwal/Flickr/Creative Commons License

The birds aren't picky eaters. They'll happily gorge on insects, frogs, lizards, eggs and baby birds, berries and fruit, and seeds small and large. They seem especially fond of acorns as a food for caching, to the point where they'll steal from acorn woodpeckers' "granary trees."

Even the best inventory management system has its drawbacks, though, and jays do lose a significant portion of their acorn caches to germination. There isn't much most oak seeds need to germinate well other than to be planted about one jay's-beak deep and left for a few months. Germination isn't really a loss for the jay in the long term. Before long a new tree grows from that "lost" acorn, ready to offer up hundreds of acorns a year in place of the one invested. The oaks here seem to bear good crops: each shrub bears hundreds of empty caps still attached to their twigs.

Scrub jays have a life expectancy of about nine years, which means some of them here may be older than the fire. It's tempting to imagine them looking on their restored forest with some satisfaction.

It's possible that this shift from conifers to oaks is a semi-permanent change in the landscape. Eventually, a jay may decide to cache a beak-full of pine nuts and juniper berries in a convenient spot that will grow into new seed sources for recolonization. Or not. The desert is getting warmer, and pinyons and junipers are having tough times even where they haven't been burned out. For now, it looks as though oaks are set to be the predominant vegetation in this canyon, along with a few Joshua trees that have resprouted from their bases:

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Joshua tree resprouting after fire | Chris Clarke photo

Acorns feed more than just jays. The canyon seems to hold a healthy population of ground squirrels, enough to keep at least one local coyote  rather sleek and fat, and to feed the local population of speckled rattlesnakes. The oaks' thick canopy shades the soil beneath: inviting habitat for insects to feed the cactus wrens now singing noisily. This nice little piece of desert seems on the mend, after a fashion, and scrub jays deserve a lot of the credit.

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commented 2012-09-26 00:37:17 -0700 · Flag
I loved the Scrub Jays on my property up in Anza. I planted some Rhamnus californica in my landscape and the Jays harvested big time those berries. I didn’t realize this until one spring when I was looking at the dander underneath one of my huge Manzanita shrubs. There were about 20 seedlings which were germinating. I thought it was kool until I decided to transplant some of them, by the Damping Off pathogen had already gone to work. Well, no matter, such dander is a protection for the Manzanita as well.
published this page in News 2012-06-24 11:02:36 -0700