Friday, April 10, 2015

8-Apr-2011 Golden Gardens Park, Seattle, Washington

Site location
Since Rod was unavailable for a combined field trip, I did another round of solo cone tapping, this time in Seattle's Golden Gardens Park.  Most of the public activity in this park is on the beach, but I found what I was looking for inland on the forested bluff: fallen pine cones.

Sample site
Try as I might, I never was able to figure out whether the pines here were introduced eastern white pines (Pinus strobus), like those I found in Green Lake Park, or the local native species western white pine (P. monticola).  Both are remarkably similar in appearance, and even the city forester was unable to confirm for me which species made up this stand in Golden Gardens Park.  Since the cones of the two species greatly overlap in size, perhaps the distinction is an academic one and is irrelevant to the spiders using them.

Native understory snuffed out by
invasive English ivy
Cone swallowed in ivy
What I do know for sure is that the entire forest was blanketed with layer upon layer of invasive English ivy (Hedera helix).  The ivy had thoroughly decimated the native forest undergrowth.  The stuff was so thick that my feet "sank" out of view.  Likewise, many cones were fairly well nestled within the ivy's matrix.

Tapping 76 cones I collected 55 spiders and 8 species.  As at Green Lake Park a few weeks before, 3 of these species were introduced: Lepthyphantes tenuis (Linyphiidae), Philodromus dispar (Philodromidae) and Theridion bimaculatum (Theridiidae).  Philodromus dispar was the most numerous identifiable species present (9 individuals), while the native Theridion sexpunctatum (Theridiidae) came in a close second (8 individuals).

A Cryphoeca exlineae in web
Another C. exlineae in web
At the time I was collecting, however, my attention and camera were drawn to individuals of the native agelenid Cryphoeca exlineae because they were conspicuous in their webs.  The concave upper side of P. strobus and P. monticola cone scales is apparently a good place to build such structures.

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