10-Sept-2014 Columbia Historic State Park, Columbia, California

My home away form home (Palo Alto, CA) in relation to the
theoretical location of local ponderosa pines. Map source.

Finding myself unexpectedly in Palo Alto, California on family business for the final quarter of 2014, I took the opportunity to conduct an experiment on the efficiency of my cone tapping method (more on that here).  Since I've focused most of my west coast sampling on ponderosa pine (Pinus ponderosa) cones, it was the logical species to use.  But where to find them?

A little Googling turned up a map in Griffin & Critchfield (1976) showing that in central Calif., ponderosas are concentrated along the western spine of the Sierra Nevada range.  This made sense, since the Sierras are the southern extension of the ponderosa-rich Cascades range in the Pacific Northwest where I've done so much cone spider sampling.  The map also showed a smattering of trees near the coast in Santa Cruz and Monterey counties.  Most intriguing!  But those mysterious coastal ponderosas would have to wait, since intrigue wasn't the only factor driving my choice of sites today.

Columbia Historic State Park

Ponderosa pines bordering
parking lot

Wanting to maximize the likelihood of finding plentiful cones quickly between the morning drop-off and evening pick-up of a family member at the San Jose airport, I selected Sonora as my destination.  Google Map's Street View seemed to confirm Griffin & Critchfield’s old (1976) report that ponderosa pines should be plentiful in and above this Sierra Nevada foothills town.  After consulting a Tuolumne County map obtained from a visitor information office in Sonora, I decided to first explore the nearby Columbia Historic State Park (location map).  As luck would have it, the lower parking lot had it all: ponderosas with lots of open cones on the ground, picnic tables with at least some shade (it was a scorcher of a day), public bathrooms and drinking water.

Spider-filled cones in the ditch.

I filled a paper grocery bag with 35 cones collected from the forest floor and the shallow, Acer macrophyllum leaf-filled ditch separating it from the parking lot, spread my sorting cloth on a picnic table, and proceeded to process the cones.

Among the 13 spiders I collected were two juvenile Euryopis sp. (Theridiidae).  In eastern Washington, Euryopis formosa are only reliably found in ponderosa cones, so this is an interesting find.  One diminutive specimen was lost to a gust of wind, and I had to chase the shade by moving to a new table several times, but otherwise the day went smoothly.

One of several Kibramoa sp. (Plectreuridae)
females present in the cones.

Hurtling back through oak savannas, then the fruit and nut orchards of a dusty San Joaquin valley (lighted highways signs reminded me not to waste water during this period of drought), I stopped in Manteca (what a name for a city!) for a restorative dose of El Pollo Loco before making a bee-line back to Mineta San Jose International Airport just in time to pick up my passenger.

To my knowledge, this blog post constitutes the first time that spiders have been reported in the fallen cone microhabitat in California.