Monday, April 24, 2017

21-April-2017 Thorp Highway Bridge, Ellensburg, Washington

Site location map. Click to enlarge.
The sun was out everywhere within our driving radius and Rod had field plans ready for all possible directions. I was eager to make our first trip of the year over Snoqualmie Pass, so we agreed on a gridspace in the western outskirts of Ellensburg.  Our collecting activities were centered around the Thorp Highway bridge over the Yakima River. Despite the constant traffic noise from nearby Interstate 90, habitats were easy to access and the sunny Spring weather was a delight.

Looking upstream along the Yakima
River from the Thorp Hwy bridge. Note
swallow in lower left-hand corner.
A male Pardosa catching
some rays on a bridge post.
I collected spiders from the bridge guardrails (which hardly guarded anything, since they were only knee high!) as I walked from our parking spot on the south side of the river to my first cone tapping site. The Yakima River was really flowing fast -- several hundred cubic feet per second faster than average for that date, according to Bureau of Reclamation. I enjoyed watching northern rough-winged swallows (Stelgidopteryx serripennis) catching flying insects over the river.


Pondside ponderosas
My first cone tapping site was located on the edge of a pond created by the I-90 freeway interchange with US-97. It sounds like an awful spot to collect, but it was actually quite lovely. Ponderosa pine trees (Pinus ponderosa) lined the pond, each with an oval blanket of needles and hundreds of cones beneath.

Pholcophora americana
I tapped the usual 50 cones and collected a very unusual number of spiders: 76! That translates to more than 1.5 spiders per cone on average. Sixty-two of them (20 F, 16 M, and 26 J) were Pholcophora americana, the pholcid that Rod Crawford and I have dubbed a "pine cone spider" for its frequent presence in fallen ponderosa cones. Although I find the species at roughly 20% of sampling sites in eastern Washington, I have only once before found them at a similarly high density in cones. Additionally, they had the most annoying ability to so firmly secure themselves to the inside of my dry collecting vial that I had to take the time to "fish" each one out using a pine needle. Consequently, it took an excruciating 2.5 hrs to collect this 50-cone sample.

Other spiders tapped from this set of cones included a male of one of the tiny Neon species (Salticidae) as well as several juvenile Salticus scenicus (Salticidae). Although we frequently find S. scenicus in highly human-influenced environments, this is the first time I've found it present in the fallen cone microhabitat.

Cobbles at pond site
An Agroeca-like egg sac hanging
under a rock
The area was strewn with cobbles, so after tapping cones I decided to turn some rocks. Not too surprisingly, P. americana were plentiful among the five identifiable species I collected in that microhabitat. In many cases, they happened to be located near to other species' egg sacs. The most interesting egg sac I found was hanging from the underside of a rock like a boxer's speed bag. It resembles the egg sac of Agroeca (Liocranidae), but no Agroeca were present to confirm that.

Washington State Patrol

Fallen ponderosa cones next to WSP
Male Bassaniana utahensis in fore-
ground, female in background
Rod had spotted a pair of ponderosas on the grounds of the Washington State Patrol office, located just south of the bridge. This made an interesting second cone tapping site since, unlike the pond location, this one wasn't adjacent to a water body and was bone dry. I tapped 50 fallen cones and collected 10 spiders. Bassaniana utahensis (Thomisidae) was the most common identifiable species present, with 2 females and 1 male in the sample. Penultimate Phrurotimpus (Phrurolithidae) were also common. And, I tapped another juvenile S. scenicus from these cones!

In all I tapped 6 identifiable species from ponderosa cones near the Thorp Highway Bridge, three of them not taken from other microhabitats.

Read Rod's account of the day here.
Bassaniana utahensis in a crack in a wooden guardrail post
Morel (?) mushrooms were pushing up through the roadside leaf litter
Unfurling black cottonwood (Populus trichocarpa) leaves

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