Wednesday, May 13, 2015

15-18 Oct 2011 Klickitat County Expedition Part 4, Washington

Mt. Adams (L) and Blockhouse Butte (R)
Continuing the story from Parts 1, 2, and 3:  The last major sampling site of our expedition was located near Blockhouse Creek, a tributary to Klickitat River with headwaters near Goldendale.  This was by far the richest site of the expedition, in terms of cone spiders.

A fascinating locale, the most obvious features in the landscape were Mt. Adams in the distance, a partially mined cinder cone called Blockhouse Butte closer by, and a grass-covered lava field in the pasture.  

Ponderosas in Blockhouse Creek
cow pasture
Cone & patty blend
Another major feature of the site was cow patties.  Lots and lots of cow patties, especially around the ponderosa pine (Pinus ponderosa) trees where the fallen cone microhabitat was.  The patties seemed to be supporting a robust population of tiny flies as well as fungi.

Fungi on manure
View of a hatched spider egg
inside egg sac on cone scale
I tapped 107 cones and collected a stunning 118 spiders and 12 species.  The most numerous were Dictyna calcarata (Dictynidae), represented in my sample by 8 females and 55 juveniles.  Interestingly, we didn't collect any other specimens of that species in any other microhabitat at Blockhouse Creek, and I've never tapped it from a cone at any other site before or since.  In Washington, it has most frequently been collected in or on buildings.

Tail feather from red-tailed hawk
(Buteo jamaicensis)
I also collected 10 female Meioneta fillmorana (Linyphiidae) from the tapped cones.  Although this is the 3rd-most common species of spider found in cones in eastern Washington, we've never before or since found it in cones at such a high density.  Three females of the same undescribed species of Disembolus (Linyphiidae) I found at our previous site, Outlet Creek, rounded out the list of notables.  The high level of spider diversity and density we observed in these manure-strewn cones made me wonder whether the manure might have spiked the spiders' food chain with nutrients.  It's an interesting thought.

Site locations (click to enlarge)
It was time to start working our way back to Seattle.  The return trip took us back through Goldendale, giving me the opportunity to tap a few dozen more cones on the grounds of the Goldendale Observatory.  In all, I tapped 101 ponderosa cones there and collected 18 spiders and 4 species.  Among them was a male of an undescribed species of Agyneta (Linyphiidae) found only once before in Washington, in 1996.  It would subsequently be named A. crawfordi by Nadine Dupérré, in honor of none other than Rod Crawford.

Neobisiid pseudoscorpion (photographed
at Goldendale Observatory)
With daylight waning, we made one final, brief stop back near Satus Pass at Brooks Memorial State Park.  I tapped only 2 juvenile spiders from 25 ponderosa cones, but also 14 mature pseudoscorpions from the family Neobisiidae. 

Noticeably short in numbers and occurrence on this expedition were Euryopis formosa (Theridiidae).  After analyzing 6 years of collection data from eastern Washington, Rod Crawford and I have dubbed E. formosa a "pine cone spider" because we've found it to be the most abundant species collected from cones (27% of specimens) as well as the most frequently occurring (49% of collection sites).  Yet on the this expedition, after tapping a total of 802 ponderosa cones from 9 sampling sites and collecting a total of 333 spiders, we turned up only one E. formosa. It just goes to show how misleading it could be if we tried to draw any broad conclusions from a collection period of limited duration like this 4 day expedition.

For a non-cone-centric view of "The Great Klickitat Expedition", read Rod's account here!

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