15-Dec-2015 U-W Campus, Washington

Site location. Click to enlarge.

The weather forecast wasn't looking promising for a full day in the field at any of Rod Crawford's target sites, so instead I spent an hour tapping cones on the nearby University of Washington campus in Seattle.  The campus sports numerous eastern white pines (Pinus strobus) as well as other exotic pine species.  In some places their fallen cones are allowed to accumulate, creating habitat for spiders and other invertebrates.

Sample site, Hutchinson Hall on right.

The fallen cone microhabitat, with
cigarette butts.

For years I've been developing a mental map of pine cone deposits on campus.  The site I sampled this day, located between Hutchinson Hall and the adjacent tennis courts, was one of the first I noted years ago as I walked through campus from the Burke Museum to my bus stop by the HUB.  Four mature eastern white pines stand in a row along the sidewalk that runs the length of the area.  No shrub layer or ground cover grow here, and the litter consists of a thin veneer of pine needles and the occasional oak leaf.  The area seems to have two main functions: as a pedestrian shortcut through the tennis courts, and as a place for people in Hutchinson Hall to grab a smoke.  Cigarette butts outnumbered fallen cones near the hall's southeastern door, and there were a lot of cones...

Female Tachygyna ursina (left)
and T. vancouverana (right)

Juvenile theridiid

Air temperature never exceeded 40 F while I was there (brrr!), but this didn't seem to impede the movement of the linyphiids that hit my net.  Of the 6 spiders I tapped from 50 cones, 4 of them were linyphiids: Tachygyna vancouverana and probably Tachygyna ursina (still to be confirmed).  The other two spiders were a juvenile dictynid and a juvenile theridiid that could very well be a Platnickina tincta (=Theridion tinctum).  These are all spider species that I've tapped previously from pine cones in western Washington.

Interestingly, I found no spiders in the cones I tapped in the middle of the plot.  All spiders came from cones lying within a few inches of the building or the tennis court wall.  Was this random chance, or was it due to differences between the "inner" and "edge" cones in microclimate or predation pressure or some other factor?

Another view of the sample site.

9-Dec-2015 Fircrest, Washington

Site location. Click to enlarge.

This time of year, field trips don't always turn out as planned.  With the Puget Sound region in the midst of a multi-day series of rainstorms, I knew that it was a big gamble to attempt any field work.  But I was antsy to get back outside, so I decided to see what I could accomplish in an afternoon with less than 50% chance of rain predicted. Greater Tacoma was my destination because it is the next metropolitan area south of Federal Way, the southern-most place I've found the introduced crab spider Ozyptila praticola (Thomisidae).

"It might be raining where you are."

A southbound lane on Interstate 5 was closed due to flooding right before my exit in Fife.  This was pretty emblematic of the day: local flooding.  And intermittent downpours.  The ground was so saturated from days of rain that water was pooling and even fallen cones protected by tree foliage above were sopping wet.  Really wet cones are difficult to tap because they quickly saturate my net, which becomes muddy.  This makes it hard to see expelled spiders, especially spiderlings.  Next time I venture out on a wet day, I'll come prepared to collect cones into containers so that I can process them later, after they've dried a bit.

Sample site

Fallen cones

Anyhow, given the conditions I was finding, I decided to forego collecting and just reconnoiter the area for cone deposits that I could return to to sample some other, drier day.  Driving the 10 miles between Fife on the east side to University Place on the west side, I found several accumulations of cones.  Most of them were dropped by the exotic black pine (Piuns nigra), so when I spotted a huge native western white pine (Pinus monticola) in Fircrest, I couldn't resist tapping as many cones as my net would allow.

Female Lepthyphantes leprosus

Lepthyphantes leprosus epigynum

I was only able to find 10 cones in the public right of way, but my net quickly became too much of a mess to handle more anyways.  From them I tapped 3 spiders and 3 species, the only identifiable one being a female Lepthyphantes leprosus (Linyphiidae).  When I return in drier weather I hope I can get permission from the landowner to tap the dozens of additional cones lying on private property, because this appears to be a promising trove.

Besides coming away with a list of promising cone sampling locations for my next foray, the trip turned out to be useful in improving my knowledge of local geography.  Until now I didn't realize how big the Puyallup River is because it's scarcely visible from I-5, and I'd always flown across it without even realizing it!  Seeing it in flood stage from a local bridge caused me to add it to my mental list of potential natural barriers to the southward spread of O. praticola.

View of Puyallup River from Eells St. bridge on July, 2015. Screen grab from Google.

1-Dec-2015 Tacoma Mall, Washington

Site location. Click to enlarge.

On my most recent trip in search of the southern boundary of the introduced crab spider Ozyptila praticola (Thomisidae) in Washington state, I had leapfrogged over Tacoma and drove directly to DuPont and Lakewood, which I thought might lie in the southern reaches of the specie's local range.  Finding no O. praticola at the sites I sampled in those cities, it made sense to backtrack to Tacoma for my next sample.  Tacoma is the next major city south of the southern-most place I have confirmed O. praticola's presence (Federal Way).

Sample site. Screen grab from Google Street View.

On the drive to DuPont a few days prior, I had glimpsed several large pine trees growing around businesses near the Tacoma Mall.  Although I encountered the usual problems with most of them (cones and tree litter had been removed by groundskeepers, or fallen cones were present but not open), I did eventually find a row of shore pine (Pinus contorta) and Scots pine (Pinus sylvestris) trees planted along a stone wall supporting the raised parking lot for Macy's Furniture Gallery.  Unfortunately I have lost the photos I took at the site, but this screen grab (left) from Google Street View will suffice.  Note that there was more needle littler on the ground than is evident in this photo, but it was quite thin.

Although I was able to find 41 open or semi-open cones to tap, I found only two arachnids in them: 1 juvenile Enoplognatha probably-ovata spider, and 1 adult Paraligolophus agrestis harvestman.  Both are introduced species.  This was perhaps my most uninteresting cone sample to date.

At the moment, Federal Way remains the southern-most confirmed location of O. praticola in Washington state.  The search continues...

The spiders are out there.

29-Nov-2015 Salsbury Point Park, Washington

Site location map. Click to enlarge.

The dry spell continued long enough to provide Rod Crawford and me another opportunity to make another late-fall collection.  As our destination Rod chose Salsbury Point Park, a small county park located near the foot of the Hood Canal bridge on the northern end of the Kitsap peninsula.  It sounded like a good destination to me, since it would require much less driving than most of our trips, and according to photos on the county's website, it had pine trees.  If cones were available under those pines, I would be able to collect my first-ever cone spider sample in Kitsap County.

Fog makes for fanciful ferry crossings

Hood Canal bridge viewed from park

One of the reasons Rod selected the site was because sunshine was forecast there, and because of its western exposure.  As it turned out, fog blanketed the region for the entire day and temperatures never got above the mid 40s.  Besides creating chilly work conditions, the lack of sunshine meant that ground-active spiders weren't out.  Nevertheless, with the help of new field volunteer Ben Diehl, we managed to find plenty of spiders.  And, there were indeed cones under the pine trees!

Two of the park's several shore pines

Spongy leaf and needle litter

The park has several clumps of shore pine (Pinus contorta) planted around buildings and in little islands in the lawn.  Although a groundskeeper was busy blowing leaves, etc. when we arrived, I had no trouble finding open cones under many of the pine trees.  I rather enjoyed crawling under the trees' low branches to reach the cones.  The pine needle litter was soft and, in one area, quite spongy with vine maple leaves.  And it was much drier than the surrounding lawn.

Many cones got eaten by Douglas
squirrels (Tamiasciurus douglasii)
before they could fall

Showy erigonine juvenile

I tapped 100 cones and collected 18 spiders.  Half of them were juvenile erigonine linyphiids with dark bodies and orange legs - very showy in my net.  The only species identifiable in my cone sample was the undescribed Tachygyna sp. #4 (Linyphiidae).  I tapped 4 females and 1 male from the cones.  Rod and Ben also collected the species from beach meadow grass, ferns and conifer foliage.  Interestingly, I did not find it in the associated needle and leaf litter that I sifted.  The only spider I found in common to both microhabitats at the site was juvenile Enoplognatha that look like ovata (Linyphiidae).

Be sure to check out Rod's take on the day here.

Douglas squirrel with a mouthful of bark that I watched it strip from
the trunk of this western red cedar (Thuja plicata)

28-Nov-2015 Lakewood and DuPont, Washington

Locations of present and previous
Ozyptila praticola sample sites. Click to enlarge.

Last week I confirmed the presence of the introduced crab spider Ozyptila praticola (Thomisidae) in the city of Federal Way, Washington.  This day I looked for it in Lakewood and DuPont, which occupy what I have theorized may be the southern end of its local range.

Lakewood

Fallen white pine cones in Lakewood

Lakewood site

My Lakewood sample site was in the Tillicum neighborhood, which is sandwiched between American Lake and Joint Base Lewis-McChord.  Two western white pines (Pinus monticola) located along the edge of a suburban yard had dropped cones onto a variety of substrates including pine needle and oak leaf litter, English ivy (Hedera helix) and decorative stones. I tapped 51 cones and collected 9 juvenile spiders.  Most were Enoplognatha sp. (Theridiidae) and Phrurotimpus sp. (Phrurolithidae).  None were crab spiders.

DuPont

Next I drove about 5 miles further south to DuPont.  My hope was to tap cones dropped by the pines shading the sidewalks in front of the Amazon Fulfillment Center and Intel Corporation.  These trees were clearly visible from aerial photos.  What I found at the site, however, was that all forest debris had been removed from the ground beneath the trees.  This included cones.

DuPont site

Fallen black pine cones in DuPont

Returning to a shopping center that I had passed on the way to my preferred site, I discovered a row of black pines (Pinus nigra) planted as a visual buffer between the road and a parking lot.  Although most of the cones that had fallen there had also been whisked away by groundskeepers, a few had escaped that fate by rolling into an undeveloped lot.  And most had come to rest on leaf or needle litter, which is a habitat amenable to O. praticola.  But tapping 44 cones, I collected only 2 spiders.  One was a male Cryptachaea (Theridiidae), the other an unknown juvenile.  Again, no crab spiders.

This was not a very exciting cone tapping day.

Mt. Rainier was barely visible through the cold fog

Our Pine Cone Spider Paper Gets An Honorable Mention

The paper that Rod Crawford and I co-wrote, "A survey of spiders found in fallen pine cones in eastern Washington State", has received honorable mention in Western North American Naturalist's ranking of outstanding natural history papers for 2014.

"The Western North American Naturalist (WNAN) is pleased to announce the award for the outstanding natural history paper of 2014.  This annual award was instituted to celebrate our authors' achievements in creative and meaningful research, insightful interpretation, and articulate writing.  Finalists were selected from the 41 regular articles published in Volume 74, and the WNAN Editorial Board members selected the outstanding paper and honorable mention papers by vote."

21-Nov-2015 Fidalgo Head, Washington

Site location. Click to enlarge.

The same sunny dry spell that made it possible for me to tap pine cones in Federal Way the day before gave Rod Crawford and me an opportunity to collect another full fall sample at one of Rod's unsampled gridspaces.  Our original plan had been to head south and collect near Matlock on the Olympic peninsula, but predicted temperatures were slightly higher for Anacortes on Fidalgo Island, so we headed north instead.

Douglas-fir & juniper on Fidalgo Head

Looking across Burrows Bay towards
Sugarloaf (left) and Mt Erie (right)

Our sampling site was a rocky prominence called Fidalgo Head, located on the northwestern point of the island.  The trail was slippery with moist red clay and caused us each to "sit unexpectedly", as Rod put it, but otherwise little effort was required to access this lovely spot.  Near to the precipitous face of the head, the dense inland forest opened to a few small grassy meadows growing on a very thin veneer of soil over bedrock.  The meadows were punctuated by Douglas-fir (Psuedotsuga menziesii), Pacific madrone (Arbutus menziesii) and tree-sized coastal junipers (Juniperus scopulorum), and featured large pockets of reindeer lichen.

Future fallen cone microhabitat:
Douglas-fir cones still on tree

Fallen Douglas-fir cones were often
near deer scat at this site.

Although I swept the meadow grass (2 species) and searched for ground-active spiders (to no avail) and spiders in webs (nothing not found elsewhere), I spent much of my time tapping Douglas-fir cones.  Since the scales on most cones were only partially opened, I adopted the method I've used with mountain hemlock cones (described here).  It is a more time-consuming procedure than conventional pine cone tapping, but worth the effort.  Tapping 50 cones got me only 7 spiders (all linyphiids) but 4 species not collected by other means, plus 20 pseudoscorpions from the family Chthoniidae.  In all, about 1 in 6 species we collected at Fidalgo Head came from my tapped cones.

As dusk loomed, I searched webs on a boulder while Rod finished sifting moss.  A couple hiking past asked if I was collecting moths, and was I a biologist.  They were interested to learn that I was looking for spiders, asked to see some, and said they were excited to get back to camp and tell their kids that they'd met a real biologist on the trail.  Now that made my day!

Read Rod's trip narrative here and view his photo album here.

Spider collectors cast long shadows!

Sunset over the San Juan Islands

20-Nov-2015 Federal Way, Washington

Site map. Click to enlarge.

Continuing dry conditions made it possible for me to continue my search for the introduced crab spider Ozyptila praticola (Thomisidae).  My current theory is that the spider is present in the entire Seattle-Tacoma conurbation.  This area stretches from Everett in the north to DuPont in the south, and is bounded by the Snohomish River estuary and Nisqually River delta, two formidable natural barriers to the spread of Ozyptila praticola if the species isn't a strong ballooner and isn't getting an unwitting travel assist from humans (Those are two big "ifs" which I still need to research.).  Having found the species in Kent a few days prior, I jumped about 6 miles southwest to Federal Way for the present sample.

Lugubrious sample site

The fallen pine cone microhabitat

Black pines (Pinus nigra) planted along the southern and northern borders of a senior housing complex provided me with plenty of partially opened cones to sample.  I tapped 55 cones and collected 14 spiders and 4-5 species, plus some harvestmen.  Among the spider species present were "the usuals" I've been finding in this urban corridor: Tachygyna vancouverana (Linyphiidae), Cryptachaea blattea (Theridiidae), and yes, Ozyptila praticola!

O. praticola tapped from fallen pine
cones in Federal Way, Washington

While I was collecting, a steady stream of people walked by me on the narrow, unofficial path that ran between the fence and the senior apartment building.  One man asked what I was looking for, and upon hearing my answer was eager to show me an ugly sore on his leg that he insisted was from a spider bite.  He attributed it to the brown recluse, which I assured him doesn't live in our region.  Not surprisingly, people don't like hearing that they or their doctor may have made a mistaken diagnosis, and frequently stick to their opinion even though they never actually saw what bit them.  Much to this man's credit, he was willing to hear about alternate possibilities.

Mount Rainier was radiant in the distance

First Record of Pseudeuophrys lanigera (Salticidae) in North America

Pseudeuophrys lanigera tapped from
fallen pine cones in Mukilteo,
Washington, USA on 8-OCT-2015

Early in October 2015 I tapped several salticids, including one male, from 100 fallen Pinus monticola cones I found in a light industrial area of Mukilteo, Washington.  Rod Crawford has identified the male as Pseudeuophrys lanigera, a species endemic to Europe and found as far east as the Caucasus and as far north as Scotland and Denmark.  As far as we can ascertain, this constitutes the first record of the species in North America.

Photo of male showing left palp

In Europe, the species is frequently synanthropic, often found in and on buildings.  In contrast, I collected my specimens from pine cones that were lying on the ground over 100 feet from the nearest building.  The area between my collection site and nearby buildings was paved with asphalt or other impervious materials.  The only structures immediately bordering my collection area were the trunk of the pine tree, stacks of wooden pallets and other industrial debris, and a cyclone fence.  A few writers in Europe have also mentioned finding P. lanigera outdoors under stones and boards, and on tree bark.  Eugène Simon, the French entomologist who described the species in 1871, wrote that it was common in the south of France on sun-exposed rock walls and arid places.

Location of Mukilteo, Washington

More sampling will be required to determine whether my specimens represent a naturalized, self-sustaining population.  But we can say now and with certainty that pine cone tapping has once again revealed the presence of a spider species in Washington state not previously detected by more conventional methods of sampling.

Update (25-Jan-2018): You can read our subsequent paper about P. lanigera in Washington state here or here.

Fallen cones containing P. lanigera
were lying in an industrial yard.

16-Nov-2015 Yangzhou Park, Kent, Washington

Site location (click to enlarge)

A few hours lull in the rain allowed me to make my first foray south of Seattle in search of the introduced crab spider Ozyptila praticola (Thomisidae).  My destination was Kent, a small city about 10 miles south of Seattle's Beer Sheva Park, the southern-most place in Washington where I've documented the presence of O. praticola.  I headed first to Kent's branch of the King County Library because Google Street View had revealed numerous pines in its parking lot.  Disappointingly, all cones had been removed by groundskeepers.  But from there I was able to spot the pine that was to be my sampling site.

Most of the fallen cone microhabitat
was on the railroad side of the fence

A lovely setting for cone tapping

Across the railroad tracks from the library sits Yangzhou Park, which features a lovely little friendship pagoda from Kent's sister city Yangshou, China, and a pine tree that had dropped over 100 cones.  Although the scales on most of the cones were barely open, I decided they were worth tapping since I've found that O. praticola can be found in such tight places, and because most of the cones were resting on pine needle and broadleaf litter, a substrate amenable to my target species.

O. praticola juveniles tapped from cones
in Yangzhou Park in Kent, Washington

I tapped 95 cones and collected 5 juvenile Ozyptila that were colored and patterned like praticola, and 1 harvestman.  This is the first time that I've tapped only one species of spider from a set of cones in western Washington.  I was especially surprised by this result given that I had tapped almost twice the number of cones that I consider a full sample (50).  The poorly-opened scales could perhaps explain the absence of other species, but it hasn't been a barrier before, especially not to juvenile linyphiids.

I returned to the safe side of the fence before each train roared by.