Tuesday, November 8, 2016

6-Nov-2016 Bellingham, Washington

Site location map. Click to enlarge.
I was all set to drive to Olympia to look for the introduced crab spider Ozyptila praticola, happy at the thought that traffic on southbound Interstate 5 should be light since it was a Sunday morning. But right before leaving, just to be on the safe side, I decided to check the traffic conditions. Good thing I did! An accident in Tacoma was blocking all but one lane. But northbound traffic was still moving smoothly, so Bellingham became my last-minute destination for the day.

I hadn't found any O. praticola on a recent trip to Burlington, the closest urban center south of Bellingham, but I still thought it likely to be present in Bellingham and the northwestern corner of the state, at least along the I-5 corridor.  This is because it's been collected just over the Canadian border near Vancouver, British Columbia (see map at end of post).  So although Bellingham wasn't my original destination for the day, I didn't mind traffic conditions diverting me there.

Bellingham has no shortage of pines, I found, but there was a distinct shortage of fallen cones beneath them due to groundskeeping practices. However, after searching diligently I eventually found two collection sites, each consisting of one western white pine (Pinus monticola) with fallen cones beneath.

Lincoln Street Underpass

Site on Lincoln Street near
I-5 underpass. Pine on left.
Lincoln St. cones were barely open
A pine tree dominated the space between the the sidewalk and someone's privacy fence, and had dropped numerous cones on a thick bed of needle litter with miscellaneous bits of trash mixed in. Most of the cones were only partially open and quite wet from recent rain. And in fact my net got wetter with each cone I tapped, to the extent that I was ruing the fact that I'd left my spare net at home.  But the result was worth it: I tapped 66 spiders and 6 identifiable species from those 50 cones!

Male Centromerita bicolor tapped
from a pine cone
Tachygyna vancouverana males
For the most part, the sample composition was typical of what I've found previously in Washington's I-5 corridor: lots of juvenile Philodromus and Enophlognatha, a few Tegenaria and some adult Tenuiphantes tenuis and Tachygyna vancouverana.  What was unusual, however, was that T. vancouverana made up over a third of the sample.  They were everywhere, both males (7) and females (24). In addition, this sample contained a novelty in terms of cone tapping: Centromerita bicolor, another introduced linyphiid.  It was first found in Washington in 1975 by Rod Crawford, in Seattle.  He collected it again in 1988 in Bellingham, just a mile or so from my Lincoln Street site.  Apparently it's naturalized in Bellingham.  And finally, I tapped from these cones one juvenile Ozyptila with praticola coloring and patterning.

James Street at Whatcom Creek

My James St. pine cone
source
The James St. fallen cone
microhabitat
My second site was only about a quarter of a mile (0.4 km) to the northwest of the first site, as the crow flies.  But with daylight rapidly fading (sunset at 4:40 p.m.!), I was just happy to have found another cone source.  It was another western white pine, this time standing in the grassy area between Whatcom Creek and a parking lot.  A tangle of Himalayan blackberry (Rubus armeniacus) growing at its base had recently been cut back, making the fallen pine cones beneath accessible to me.  I often grumble about groundskeepers, but in this case they'd inadvertently done me a good turn.

Juvenile Ozyptila from James St. site
As at the first site, the scales on the cones here were poorly opened, yet they were open far enough for many spiders to have entered.  I was only able to find 25 cones to tap, but they delivered 14 spiders and one identifiable species, Phrurotimpus boralis. The rest of the sample was very much like a subset of the Lincoln St. sample including, once again, one juvenile Ozyptila with praticola coloring and patterning. As the saying goes, "so close and yet so far".

Ozyptila praticola collection sites in WA and B.C.
Blue: Confirmed with adult specimen; Yellow: Juvenile possible O. praticola;
Red: No O. praticola found. Note: B.C. records via Bennett et. al 2014

The banks of Whatcom Creek are choked with invasive Himalayan
blackberry, which incidentally originated in Armenia and Iran, not the Himalayas.

Wednesday, November 2, 2016

25-Oct-2016 Burlington, Washington

Site location map. Click to enlarge.
A very rainy October slowed my hunt for the introduced crab spider Ozyptila praticola (Thomisidae), but I was finally able to get in one solid day of searching before turning the page on the calendar.  My destination was the Burlington metro area, which includes Mt. Vernon to the south and Sedro-Woolley to the northeast.

Fallen Pinus nigra cones
In total I tapped 52 spiders from 380 pine cones (Pinus nigra, P. sylvestris, P. strobus or monticola and P. ponderosa) across 7 sites.  As readers of this blog know, I usually describe the catch from each sampling site separately.  But the results were so unremarkable and typical of what I find in fallen cones in the Interstate 5 urban corridor that I'm just going to provide a combined summary this time.

The only thomisids I found in these cones were a few juvenile Xysticus.  Thus, no Ozyptila. Tenuiphantes tenuis and Tachygyna vancouverana were the most common identifiable species present, while juvenile Enoplognatha probably-ovata and Philodromus were numerous and widespread.  A mishmash of other juvenile linyphiids, theridiids and agelenids made up the rest of the combined sample.

Rain showers and sunshine created this beautiful rainbow in Sedro-Wooley