Monday, April 13, 2015

12-Apr-2011 Washington State Horse Park, Cle Elum, Washington

Site location
Eager to get back into a ponderosa pine (Pinus ponderosa) forest, I drove east from Seattle over Snoqualmie Pass to Washington State Horse Park.  Located on the west side of Cle Elum, this 112-acre forest was dominated by ponderosa pine and dotted with Douglas-fir (Psuedotsuga menziesii).

Sample site
Old ponderosa cones
Although spring had yet to, well, spring forth, most of the snow had melted and exposed extensive accumulations of ponderosa cones and, here and there, Douglas-fir cones too.  Interestingly, the scales on most of the ponderosa cones were open only on the upper, exposed side, whereas all of the scales on many of the Douglas-fir cones were completely open.

Euryopis formosa cryptic
with cone debris
Rod had warned me that it was too early in the season to find much at this elevation (almost 2,000 feet), and he was right.  Tapping 103 ponderosa cones got me only 9 spiders.  But my efforts were not for nothing, since 3 species were identifiable.  These included Euryopis formosa (Theridiidae), a species we'd eventually come to term a true "pine cone spider" since fallen pine cones are, so far, the only reliable microhabitat in which it is found in Washington.

Douglas-fir cone with spider signs
I also tapped 100 Douglas-fir cones and got only 3 spiders, all juveniles.  Despite the high vacancy rate, I could tell that spiders had used these Douglas-fir cones fairly extensively, since they'd left behind numerous webs and refugia.  Deyrup & Deyrup (1978)* noted that "Douglas-fir cones, though occasionally inhabited by spiders, are poor habitats for large or mobile predators because the cones close tightly during wet weather, leaving only a minute space at the base of each scale."  However, their study was conducted in Seattle, known for its damp climate.  I wonder if Douglas-fir cones might provide a more lasting microhabitat for spiders in drier climates like found in Cle Elum and elsewhere on the eastern slope of the Cascade Range?

*Deyrup, M. & N. Deyrup (1978) Pupation of Hemerobius in Douglas-fir cones. Pan-Pacific Entomologist 54:143–146.

First hint of spring, the aptly-name spring-beauty (Claytonia sp.)

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