Friday, August 18, 2017

16-Aug-2017 Mount Vernon and Bellingham, Washington

Site location map. Click to enlarge.
Ever since finding juvenile Ozyptila that were patterned like praticola at two sites in Bellingham last November, I've been wanting to return to search for adult specimens. I wanted to know conclusively whether this introduced thomisid was present in Whatcom County's biggest city. It seemed likely, given Bellingham's situation along Interstate 5 and its proximity to British Columbia's southern reaches, where O. praticola has also been found. This would be the day to find out! But first, on my way north from Seattle to Bellingham, I stopped in Mount Vernon and Bow to take a few more samples in Skagit County; I have yet to find O. praticola (or any Ozyptila) in fallen conifer cones in Skagit County.

Mount Vernon & Bow

Anderson Rd site
Lots of cones & litter under the shrubs
On past trips north I'd noticed a row of pines growing just east of the freeway near the Anderson Road exit. Upon closer inspection this day, I found that groundskeepers had removed all of the cones and needle litter from beneath them. But it didn't take long to find "greener pastures" on the other side of the freeway: black pines (Pinus nigra) planted along a parking lot perimeter. Groundskeepers had been busy there too, but hadn't gone so far as to remove cones and litter from beneath the shrubs.

Zodarion collection sites.  Blue = Zodarion rubidum adult;
Yellow = juvenile Zodarion 
I tapped 50 cones and collected 37 spiders from four families. Most were juvenile Steatoda (Theridiidae) and Philodromus (Philodromidae). The only identifiable species was Tenuiphantes tenuis (Linyphiidae). By far the most interesting spider in the sample was a juvenile Zodarion (Zodariidae), presumably Z. rubidum. This is the farthest north I've found this rapidly spreading introduced species. I also sifted pine needle litter, but didn't find anything new. I found no O. praticola in either microhabitat.

Bow Hill Rest Area
Bow Hill Rest Area along Interstate 5 provided another convenient spot to tap cones in Skagit County. The facility is situated in a fairly natural forest fragment dominated by western red-cedar (Thuja plicata) and Douglas-fir (Pseudotsuga menziesii). Nevertheless, the 50 Douglas-fir cones I tapped produced only two harvestmen and two juvenile linyphiids.


Lincoln St. site
Since I already knew that Ozyptila could be found at the two Bellingham sites I had sampled previously, I decided to intensively re-sample those sites before looking for new ones. My first stop was the western white pine (Pinus monticola) growing on Lincoln St. near the Interstate 5 underpass. Except for the need to wade through thorny Himalayan blackberry (Rubus armeniacus), I had no trouble finding 50 fully opened cones to tap.

Female Steatoda bipunctata
Those 50 cones produced an astounding 100 spiders, 64 of which were the introduced Steatoda bipunctata (Theridiidae). I also collected two female Eratigena agrestis (Agelenidae), commonly known as hobo spiders. Juvenile agelenids aren't uncommon in the fallen cone microhabitat, but this is the first time I've collected mature E. agrestis. I suspect the reason is that most cones that I tap don't provide large enough hiding places for Eratigena adults, which have body lengths of 11-15 mm (legs not included). As for O. praticola, I again found but one juvenile spider at the Lincoln St. site. My plan had been to sift litter if I didn't find an adult specimen in the cones, but I decided against it unless my second Bellingham site proved equally unhelpful. The reason was the poor dog on the other side of the fence that had been barking for the past hour and a half. I was sure that I, it and its neighbors would enjoy a reprieve.

This unassuming site on James St. ...
...harbored this male Ozyptila praticola
Moving on, I was pleased to find that the western white pine at the intersection of Whatcom Creek and James street also had numerous fully opened cones beneath it. I tapped 50 cones and collected 24 spiders from 5 families. Only two species were identifiable: T. tenuis and, O. praticola! So now we know with certainty; Ozyptila praticola is indeed present in Bellingham.
Status of Ozyptila praticola in western Washington. Blue, yellow, or red
indicate adult O. praticola, juvenile Ozyptila sp. or no Ozyptila found, respectively

Wednesday, August 9, 2017

8-Aug-2017 Bainbridge Island, Washington

Site location map. Yellow pin marks Harborview Drive site.
Click to enlarge.
Smoke from wildfires in British Columbia precluded a trip to the gridspace of interest to Rod, so I took a solo trip to Bainbridge Island (Kitsap County) to continue my search for the introduced European thomisid Ozyptila praticola. So far I haven't found any O. praticola on the nearby Kitsap Peninsula, but it is present on Vashon Island five miles to the south of Bainbridge Island. Both islands are connected by frequent ferry traffic to Seattle, where O. praticola is now common.

Sampling site on Harborview Dr.
The fallen cone microhabitat
Almost immediately after disembarking from the ferry, I found a nice cache of fallen cones to tap on Harborview Drive. The cones were a jumble of Douglas-fir (Pseudotsuga menziesii) and black pine (Pinus nigra) cones intermingled with Douglas-fir and madrone (Arbutus menziesii) litter.

Juvenile Ozyptila (?praticola?)
O. praticola in western WA. Blue,
yellow & red pins indicate adult, juvenile
or no O. praticola found, respectively.
I tapped 100 cones and collected 26 spiders. Most were Cryptachaea blattea (Theridiidae), but two were juvenile Ozyptila. They look like O. praticola to me, but unfortunately I can't definitively identify the species from juvenile specimens, so a return trip with litter sifting equipment in tow will be required.

The other four Bainbridge Island sites I sampled produced more C. blattea as well as juvenile specimens of Tegenaria, Tenuiphantes, Philodromus, and Phrurotimpus. In all, very typical for fallen cones in urban western Washington.

Seattle skyline seen through the milky haze of wildfire smoke from the
deck of the M/V Tacoma.

Saturday, August 5, 2017

30-July-2017 Ferbrache Unit, Washington

Site location map. Click to enlarge.
With choices of productive sampling sites dwindling rapidly due to summer heat and dryness, Rod Crawford and I returned to a favorite late-season region, Grays Harbor County. Our main collecting site had the interesting name Ferbrache Unit, which I kept confusing in my mind with Fibonacci, as in the mathematical sequence. The area consists of Chehalis River sloughs, forest remnants and agricultural fields managed for waterfowl. My source of fallen cones was the one and only Sitka spruce (Picea sitchensis) growing on the forested edge of one such grassy field.

Rod dwarfed by the Sitka spruce and
its encircling jungle.
Looking across grassy field
at the giant Sitka spruce.
The tree was a giant and sported a massive skirt of Himalayan blackberry (Rubus armeniacus) and coastal manroot (Marah oregana or M. oreganus). The latter resembles the edible cucumber and belongs to the same family (Cucurbitaceae), but is apparently not edible.

First set of tapped cones returned
to the grassy field
Numerous cones had fallen on the grassy field, so I tapped 57 of them while Rod beat the few reachable spruce branches and the tree's skirt of foliage. My efforts resulted in only one juvenile spider.

Fallen cones near tree base made up
the second set
By the time I was done with that first set of cones, Rod had made a big enough hole in the wall of green (a machete would have been useful!) for me to worm my way through to the trunk of the tree.

Inside the manroot tangle
I was pleased to find vast quantities of cones under the pleasantly green and less-dry tree canopy and manroot tangle. I tapped 100 cones from that cache and collected 11 spiders and a few neobisiid pseudoscorpions. Compared to the lone juvenile spider I'd tapped from the "field" cones just a few yards away, this was a bountiful result.

All eleven spiders were juvenile except for a male and female Ceratinella (Linyphiidae) which didn't immediately match any species Rod was familiar with. Two of the juveniles were Metallina (Tetragnathidae), a genus I'd never found in fallen cones before. In fact, I rarely find anything from the family Tetragnathidae in fallen cones. Rod also collected many juvenile Metallina in his Ferbrache Unit sweep samples.

Read Rod's account here.

A field of peas across the road from the Ferbrache Unit.