Tuesday, June 28, 2016

21-June-2016 From Gold Bar to Skykomish, Washington

Site location map. Click to enlarge.
On a previous trip to the Skykomish River valley in search of the introduced crab spider Ozyptila praticola, I found adult specimens in Monroe, none in Sultan or Startup, and then one juvenile in Gold Bar.  My plan this day was to continue my search "upstream" (southeastward) as far as the town of Skykomish.  My first stops were in Index and Baring, but much to my disappointment I was unable to find any accessible cones to tap in either community.  I had better luck in Grotto and Skykomish, and ended the day taking an additional sample in Gold Bar.


"Safety follows wisdom"
Grotto is a tiny community at the foot of Baring Mountain.  A "safety trophy" awarded to the Northwest Portland Cement Co. for a "perfect safety record in 1954" is the only clue to Grotto's dusty industrial past; it was a town constructed in 1927 by Portland Cement as the site of a cement plant that processed limestone quarried from the hillsides of the Lowe Creek valley, located across the Skykomish River. The plant was dismantled in 1967, but a small community remains.  Interestingly, all of the online historical information I found on Grotto had been assembled by model train enthusiasts!

Cone source trees in foreground
and background
My cone source was three mature Douglas-fir trees (Pseudotsuga menziesii) on a street corner.  Many of the cones were still damp from rain the previous night and had only partially opened scales.  Nonetheless, I was able to tap a total of 100 cones of reasonable quality from two separate accumulations.  In all those cones I only found 2 spiders, both female Tenuiphantes tenuis (Linyphiidae).

Some of the drier fallen cones in Grotto
Though the spider population in these fallen cones was disappointing, the human population in Grotto was a delight.  I enjoyed conversation with a woman from the Bay Area of California who was visiting her daughter, and a young mother whose yard was bordered by one of the cone-dropping trees.  Even a UPS delivery person stopped briefly to ask what I was collecting, and to find out more about a spider he's been seeing in his home in Monroe.  Grotto is definitely on my list of most welcoming places to search for spiders!


BNSF train rolling through Skykomish
My Skykomish cone source
By the time I got to Skykomish I was ready for lunch, so stopped by the Cascadia Inn's cafe.  As in Grotto, I enjoyed more friendly spider-centric conversation, this time with the waitress, while watching BNSF trains roll slowly by.  Quite enjoyable!

Erigone male's carapace edged in denticles
The good thing about small towns like this is it doesn't take long to search the area for cone deposits.  I quickly found more fallen Douglas-fir cones on a sidewalk near the post office.  The sidewalk was covered in tree needle litter, cones and herbs.  Clearly nobody had trod on it for years, much to my benefit.  I tapped 50 fallen cones and collected 3 mature spiders, all Erigone (Linyphiidae).

Gold Bar

Mystery spider from Gold Bar
Mystery spider from Gold Bar
Turning towards home, I decide to tap another set of cones in Gold Bar to see if I could replicate my earlier discovery of O. praticola there.  I returned to the grocery store parking lot where I'd found the single juvenile specimen earlier in the year, but tapped a different group of cones than before.  From 50 fallen Douglas-fir cones I collected 3 spiders and 2 species. One was Enoplognatha thoracica (Theridiidae), which I had tapped from cones in Gold Bar before.  The other was a mysterious female spider Rod Crawford dubbed "curious" after seeing photos.
UPDATE [3 July 2016]: The mystery spider is Zodarion rubidum (Zodariidae). Read more about the significance of that here.

The spider yield from fallen cones was uniformly very low on this field trip, perhaps a symptom of the advancing summer dry season.  The day after I took these samples, Rod went on a collecting trip in the hills above Index and found litter spiders to be sparse there as well. However, summer dryness doesn't drive O. praticola from fallen cones in some small plots that I monitor monthly in Seattle, so I doubt that was a factor in O. praticola's absence from samples this day either.  But that's just a guess.

A bridge over the South Fork of the Skykomish River. A sign reads "One car at a time",
for obvious reasons. Another sign advises drivers to "retract mirrors before crossing".

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