Friday, July 3, 2015

30-Jun-2015 Icicle Gorge Trail, Washington

Washington locations where Theridion rabuni has been found
Rod Crawford and I were both interested in collecting along Icicle Creek, which constitutes the southern border of the Chiwaukum Mountains.  I was excited to collect anywhere in or around the Chiwaukum Mountains, since it's the only area in Washington where we've found Theridion rabuni (Theridiidae), and I wanted to see if we could find more (see map, right).  Now seemed to be our best opportunity since T. rabuni appears to mature in Washington in late June or early July.  For his part, Rod was interested in completing the gridspace sample I started in 2009 when I tapped cones containing T. rabuni and 4 other species near the mouth of Chatter Creek, a tributary to Icicle Creek. 

My only hesitation in collecting there was the continuing record-breaking heat wave across the state.  A few weeks prior, we had to cut short our visit to Peavine Canyon because I got overexposed to the heat.  I didn't want that to happen again, but I also didn't want to miss this year's window of opportunity for finding more T. rabuni.  I decided that the maximum temperature of 88 F (31 C) predicted for our target area was manageable, so we decided to go for it.

Nason Creek R.A., Rte 2 in distance.
If you think this looks uninviting,
you're not thinking like a spider!
Ponderosa cones at Nason Creek R.A.
On the way to our destination we stopped at Nason Creek Rest Area to tap some ponderosa pine (Pinus ponderosa) cones.  I've tapped cones here before, once in July 2010 and again in April 2011, and was curious to see if we could replicate my July 2010 find of T. rabuni.  Rod was eager to get to Icicle Creek, so we split the task, each tapping 25 cones from accumulations I hadn't sampled previously.  Interestingly, although we were working only a few hundred feet apart, the cones Rod tapped contained only 4 spiders while those I tapped contained a surprising 50 spiders.  The difference was largely due to the presence of 40 juvenile Pholcophora americana (Pholcidae) in my cones.  It does seem likely that P. americana had been reproducing in them!

The distinctive bark patterns
of western redcedar (left) and
western white pine (right)
Western white pine cone
After arriving in the Icicle Creek valley and finding a coveted shady parking spot at the Icicle Gorge Trail trailhead, I headed down the trail towards Chatter Creek to look for cones.  The trail between the trailhead and the Icicle Creek footbridge had a lot to offer in the way of pines: huge ponderosas, numerous lodgepole pines (Pinus contorta var. latifolia) and a dense stand of western white pine (P. monticola) mixed with western redcedar (Thuja plicata).  Enjoying the combination of the dense shade and cooling winds in the western white pine stand, I decided to take my main sample there.  Tapping 50 fallen cones I collected 15 spiders and 3 species. A full bag of associated conifer needle litter produced 7 spiders and 1 species, Cryphoeca exlineae (Agelenidae), which I'd also tapped from the cones.

Ponderosa cone site at trailhead
Ponderosa cones amid
bearberry and blueberry
Even after hours of intense collecting, Rod wasn't confident that we'd collected enough species to bring the gridspace total to over 21.  While he sampled one last round of conifer foliage, I decided to tap a bonus round of ponderosa cones in the area near the trailhead picnic table.  From 50 cones I collected 6 spiders, four of which were Euryopis formosa (Theridiidae) spiderlings.

A view of Icicle Creek from the trail
Looking up at P. monticola
As to my quest to find more Theridion rabuni, neither of us collected any.  If it is still present in the area, I wonder whether the unusually early summer heat may have accelerated its time of maturation.  If so, then this year's window of opportunity for finding it in cones was earlier than usual, and we missed it.  Seems as good a theory as any.

The white "bones" of trees killed by the 2004 Icicle Fire still stand in stark contrast to the neighboring forest.
As seen from Icicle Creek Road.

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