Thursday, September 22, 2016

20-Sept-2016 Marysville, Arlington and Mt. Vernon, Washington

Site location map. Click to enlarge.
Time to re-draw the Ozyptila praticola (Thomisidae) range map again!  I returned to the field this week to continue my search for the northern edge of this introduced crab spider's range in western Washington.  I had previously sampled the urban corridor along Interstate 5 as far north as Arlington (as well as several non-urban sites well beyond there), but had not found any O. praticola beyond Granite Falls.

Although I sampled in Arlington in October 2015, I considered the city under-sampled since I had only tapped one full set (50) and one partial set (13) of cones there.  Further, the partial set of cones had been lying in tall grass, a situation that I've found to be unattractive to O. praticola in western Washington.  So I returned to Arlington in search of at least one more set of more suitably situated cones to tap.

Arlington Denny's

A welcome sight right off
the freeway
Fallen cones on pine needle litter: a
good place to look for O. praticola
Exiting I-5 onto eastbound Route 530, the first thing I saw was a Denny's restaurant with black pines (Pinus nigra) growing next to its parking lot.  How fortuitous!  Most of the 50 fallen cones I tapped had only partially opened scales and contained significant amounts of organic debris, but also 32 spiders from 6 families.  Forty percent of them (13) were juvenile Crustulina, presumably sticta (Theridiidae), a spider I have found in fallen cones before, but rarely.  Interestingly, all 13 were from a small number of neighboring cones.  The next most common spider present were juvenile Enoplognatha ?ovata (Theridiidae), a common spider in urban cones in western Washington.  As for O. praticola, it was a no-show until I tapped my 49th cone, which produced a mature female!

Mt. Vernon

An inviting spot south of Mt. Vernon
Lots of cones but few spiders
Next stop was Mt. Vernon, a lovely little city in the Skagit delta.  I searched downtown and the industrial zone to its south for pines, and found many.  But what I didn't find were cones.  Groundskeepers had swept them all away.  It wasn't until I hit the city's southern rural outskirts that I found an accumulation of accessible pine cones.  Black pine once again, this time planted along the fence at a plant nursery.  I tapped the usual 50 cones but only got 4 spiders: all juvenile Philodromus (Philodromidae). Oh well.

Marysville Public Works

How could I resist?!
Excellent fallen cone microhabitat
at Marysville Public Works
Heading home towards Seattle, I decided to take the scenic route from Mt. Vernon through Marysville before returning to the hurly-burly of the interstate.  I'm sure glad I did!  Just a few blocks before I had to get back on I-5, I spotted a delicious row of large black pines growing along the fence line of the Public Works.  Only one tree was accessible to me, but it had dropped plenty of cones that a) had escaped groundskeepers and b) had accumulated on pine needle litter.  I was in clover.

Male Crustulina sticta. Note the
Steatoda patterning on his dorsum.
The characteristic granulations were
visible on the sternum as well as carapace
So much so that I didn't pay attention to the time (6:30 p.m.) and almost got locked into that parking lot!  I had just captured the spiders from cones 41 through 45 in my dry vial when I heard the gate being dragged closed.  That sure snapped me out of my reverie!  The employee kindly held the gate for me while I jumped in my car and zipped by, one thumb still stoppering my dry vial.  As soon as I cleared the gate I had to pull over and transfer those spiders to my alcohol vial.  Although I had only managed to tap 45 cones, I collected a whopping 45 spiders!  Twenty-six of them were juvenile Philodromus, 7 were Tenuiphantes tenuis and 6 were O. praticola.  I also captured 3 more Crustulina sticta, including a mature male.

At present, Arlington is the northern edge of O. praticola's known range in western Washington.  The search will continue...

Evening sun illuminates the Marysville water tower.

Rich farmlands of the Skagit delta were just across the
street from my Mt. Vernon site.

Saturday, September 17, 2016

A Preliminary Look At The Phenology of Adult Ozyptila praticola (Thomisidae) in Western Washington

Whenever I take a break from collecting, I'm itching the whole time to resume field work as soon as I can.  But breaks do give me time to take an unhurried look at the data I've recently collected to see whether I've learned anything unexpected.  I've been doing this with my Ozyptila praticola project data.

The goal of the O. praticola project has been simply to determine the distribution of this introduced crab spider in Washington state, as found in the fallen conifer cone microhabitat.  But in the process of pursuing that goal, I've collected some interesting life history data on the species.  In this case, adult phenology.

The Spiders of Europe and British Arachnological Society's Spider Recording Scheme ("SRS") web pages for O. praticola both report that mature males and females have been collected every month of the year in their regions of coverage. Similarly, within their local range here in Washington, I have found adult O. praticola present every month that I've searched (February through November) except for February, a woefully under-sampled month represented so far by only one 50-cone sample.

Before graphing the monthly occurrence of females and males in my collection, I standardized numbers of specimens of each sex I collected each month by converting them to a per 100 cones tapped basis.  I did this because sampling effort -- defined here as numbers of cones tapped per month -- varied greatly from month to month (see chart, right).

The resulting chart shows that female O. praticola have been present in my samples in fairly consistent concentrations of about 1 to 2 spiders per 100 cones every month I've sampled (excluding February, as previously discussed).  In contrast, I found males in tapped cones only in spring (April & May) and fall (September & October), and at varying concentrations.

Adapted from British Arachnological Society's
Spider Recording Scheme
Although SRS reported O. praticola males present every month, it also showed a bimodal distribution with more males having been collected in May & June and, to a lesser degree, in September, than any other month (see chart, right).  Unfortunately, it is not possible to know whether this apparent similarity in patterns between my data and data reported by SRS is meaningful since it seems doubtful that the SRS data were standardized for sampling effort, as mine were.  The SRS results could be explained simply by more British spider collectors being active in spring and fall than other seasons.

Note that my phenology chart is based on preliminary data from a study not yet completed.  So far, I've tapped 268 O. praticola from 1,895 conifer cones.  Of those 268 O. praticola, 29 (11%) were female, 14 (5%) were male and 225 (84%) were juvenile.  That's not a lot of specimens to base any conclusions on.  Still, it's more data than we had a year ago, which was almost nil.  I am excited to know whether the patterns in my chart will change with the addition of more data.  And so, as usual, I am itching more than ever to get back out into the field.

Saturday, August 27, 2016

Are Douglas-fir Cones As Depauperate In Spiders As They Appear?

Site location map. Click to enlarge.
The other day I tapped cones at two more sites near North Bend, Washington for my Ozyptila praticola project.  No pine cones being available, I tapped 50 Douglas-fir (Pseudotsuga menziesii) cones at each site and found only 1 spider in one set and two spiders in the other.  I've tapped enough Douglas-fir cones over the past year or so to have formed the impression that they seldom hold many spiders.  But is this really true?  I decided to run the numbers and find out.

Since I began my Ozyptila praticola project in May 2015, I've tapped 31 sets of black pine (Pinus nigra) cones and 35 sets of Douglas-fir cones.  These are two of the three species of cones I've tapped most frequently for this project, and they have similarly sized cones.  (Western white pine, P. monticola, is another frequent cone source but has significantly larger cones, so I excluded it from this analysis.)  Most sets consisted of 50 cones, but since not all did I standardized my data by using average number of spiders per cone per set in my calculations.  All cones tapped were from low-elevation (< 300 m) sites in western Washington.

A Douglas-fir cone: boring but worthy of tapping!
My impression about spider density in Douglas-fir cones was correct; there was a significant (P < 0.0001) difference in the average number of spiders per cone in black pine and Douglas-fir cones, a two-tailed student t-test showed (t = 4.0682, df = 64).  Black pine cones had an average of 0.28 spiders per cone, whereas Douglas-fir cones had only 0.10 spiders per cone on average, an almost 3-fold difference.

I've collected about 20 species of spiders each from black pine and Douglas-fir cones.  (A few specimens still await identification, so the exact number of species may change, but not by much.)   There are 11 species in common to the black pine and Douglas-fir cone lists.

My conclusion is that Douglas-fir cones are indeed low in number of spiders relative to black pine cones, but they're equally species-rich.  Their low relative spider frequency makes Douglas-fir cones less exciting to tap, but they're still very much worth tapping!

Oh, for those keeping track, none of the three spiders I tapped from cones near North Bend the other day were O. praticola.
View of Rattlesnake Ledge from Cedar River Watershed Education Center

Wednesday, August 24, 2016

23-Aug-2016 Carnation, Washington

Site location map.  Click to enlarge.
Key: Blue - Ozyptila praticola confirmed, Yellow - O. praticola suspected,
Red - No O. praticola found
Yesterday I returned to my search for the introduced crab spider Ozyptila praticola (Thomisidae).  Since I've already found it in two places in the Snoqualmie River valley (Snoqualmie and Duvall), I wanted to continue my search into the foothills of the Cascades mountains east of the river valley.

Maybe not the best place to collect spiders...
My focal point was the Tolt Reservoir.  On a mountain biking website I had found a detailed description of a circular route to near that point which started in Tokul and ended near Duvall.  What a windfall!  Or so it seemed until I tried driving it.  Not too far beyond Tokul, the roads were gated and posted with warning signs about written permission being required before entering.  This approach being unavailable, I decided to try driving the final segment of the route "backwards" from Duvall.  Whether that approach is open to the public I still don't know, since road names on the signs and in the instructions didn't always match up, and I didn't have all the maps with me that I thought I had.  It was one of those days...  I'll have to return another time better prepared.

Cone source, a lone pine
A fallen cone
But the day wasn't a total loss since I was able to find cones to tap in Carnation and confirm that O. praticola is present at the midpoint of the Snoqualmie River valley.  The cone source was a black pine (Pinus nigra) growing on a street corner in the business district.  Its fallen cones were on a bed of pine needles through which sparse herbs were growing.  Tapping 50 cones I collected 18 spiders, 10 of them O. praticola.  Other spiders present in these cones included a Diplostyla (Linyphiidae) female and penultmiate male, a pair of mature Tenuiphantes tenuis (Linyphiidae) and two juvenile Clubiona (Clubionidae).  The cones also contained 25 harvestmen and a number of tiny snails.

A wall of corn marks the edge of town in Carnation

Monday, August 1, 2016

27-July-2016 Mount Zion, Washington

Site location map. Click to enlarge.
We left Seattle a little earlier than usual in order to catch the 9:40 a.m. Edmonds-Kingston ferry, only to find it delayed by fog.  Well, that gave Rod Crawford and me plenty of time to talk over our collecting strategy for the day.  Our destination was Mount Zion, located a few miles northwest of Quilcene in Clallam County.  This would be my first opportunity to tap pine cones in Clallam Co.

A day for fog horns
Gnome-plant in bloom on
the dark forest floor
The Mount Zion trail must be magical to hike in the spring, when the rhododendrons are in bloom.  Rhodies are a major part of the forest understory here, growing 8-10 feet tall and in places probably creating a sort of "flowered tunnel" effect.  This time of year, nothing so showy was happening.  However, two intriguing myco-heterotrophic plant species were blooming subtly on the forest floor, woodland pinedrops (Pterospora andromedea) and gnome-plant (Hemitomes congestum).


Pine with a deceptively white
trunk
Pinedrops backlit by
a setting sun
After reaching the summit, I continued hiking along the ridge towards the southeast where some cliffs were supposed to provide an excellent view as well as, I hoped, a different spider fauna from what we were finding in the forest.  About half way to that point I was delighted to spot some western white pine (Pinus monticola) cones next to the trail.  It took me a few minutes to locate the tree dropping them because, like I'd found near Square Lake in neighboring Kitsap County, the trunk was uncharacteristically white with what I presumed were epiphytic lichens.  If I hadn't seen the cones around it or noticed the whorled branching pattern, I probably would have mistaken it for an alder.

Callobius nomeus female with egg sac
on a cliff face in the forest
Fallen cone microhabitat
I tapped 50 cones and collected 7 spiders and 3 species.  All three were common litter species, but one of them, Walckenaeria cornuella (Linyphiidae), I had never tapped from fallen conifer cones before.  And, this was the only microhabitat we collected it from this day.  In addition to spiders, these cones also contained native harvestman and centipedes.

Snail on cliff face in forest
Female Zygiella dispar with spiderlings
on a sign at the trailhead
The trail was remarkably silent the entire day.  No rushing water, no crickets, no cicadas, no birds except for one raven, no mammals except for one barking chickaree and a few passing humans.  And no airplanes flying over or highway traffic rumbling in the distance.  Just wind.  It was one of the most silent trails I've ever been on.

This rock dove (Columba livia) joined us for the morning ferry crossing to Kingston

Friday, July 29, 2016

23-July-2016 Union Creek, Washington

Site location map. Click to enlarge
Last summer Rod Crawford and I collected spiders at Sand Ridge Trailhead, located southeast of Mt. Rainier in Yakima County.  Today we decided to check out Union Creek Falls, located northeast of Mount Rainier about 20 miles due north of Sand Ridge Trailhead.  Since the elevation of the two sites is about the same, I figured I'd find ponderosa pine (Pinus ponderosa) cones to tap just as easily this time as last time.  That is always an attractive prospect to me.  But Union Creek was a doubly enticing destination since to reach it we would drive through the little enclave of Greenwater.  Greenwater is the next town "up-canyon" from Enumclaw, which is the most southeastern place I've found the introduced thomisid Ozyptila praticola in western Washington.  I was eager to make a brief cone-tapping stop in Greenwater to see if I could find O. praticola there.

Greenwater

Rod sorting a sweep sample in front of
my cone source
The fallen cone microhabitat
I decided to stop at the long-closed Buzzy's Greenwater Cafe.  Being closed, it offered plenty of parking, and the grounds were unlikely to be fastidiously manicured.  A towering Sitka spruce (Picea sitchensis) growing near the restaurant's main entrance had dropped numerous cones on tree litter and sparse herbs.

Enoplognatha thoracica
I tapped 50 cones and collected a juvenile harvestman and 2 juvenile spiders, a Xysticus and an erigonine.  I also turned over a few rocks and found a female Enoplognatha thoracica (Theridiidae), who immediately set to work rolling her egg sac, presumably in preparation for repairing the damage I had caused to her nest.  This introduced species is fairly common in western Washington; I have tapped if from cones at a dozen sites, and Rod and others have collected it from a variety of other microhabitats.  In the brief time I was tapping cones, Rod collected numerous additional species from herbs and conifer foliage.  Since Greenwater is in an unsampled gridspace, we have a good head start on a dedicated field day there.

Union Creek

Rod crossing log
bridge over Union Creek
A boulder-eye view of Union Creek
Falls and gorge
I noted a spindly western white pine (P. monticola) growing in the picnic area next to the trailhead.  I thought might come in handy if I didn't find any ponderosas on the trail.  Our first destination was Union Creek Falls, but first we had to cross Union Creek.  The creek was running just high enough that rock-hopping wasn't possible.  Then Rod spotted the makeshift bridge: a log over the creek.  Someone had thoughtfully tied a rope above it to steady the wobbly.  Just a few minutes scramble from there and we were in the small but attractive Union Creek Falls gorge enjoying a cool, fine mist from the waterfall.  There were no good cone sources here, so after collecting spiders from the creek boulders and gorge wall, I continued up the trail in search of pines.

A ponderosa (l) and white pine
(r) flank the trail but neither
provided accessible cones
Perhaps this lizard and I were doing
the same thing in this bark pile:
hunting spiders
Several times along the trail I glimpsed tantalizing pines, but all were either out of reach on the other side of boulder talus, had dropped their cones over cliffs, or were too small to produce cones.  I finally gave up and tapped 50 Douglas-fir (Pseudotsuga menziesii) cones.  The resulting 3 spiders weren't terribly exciting, but at least one was mature, a female Lepthyphantes mercedes (Linyphiidae).

White pine cone source
near trailhead
Fallen white pine cones
Upon return to the trailhead I found that the pine I'd noted earlier had only a few fallen cones beneath it.  This was a disappointment.  But as I crossed the footbridge over Union Creek on my way to find Rod and let him know I was ready to leave, I found what I was looking for.  A towering western white pine was growing on the opposite bank of Union Creek, and it had dropped dozens upon dozens of cones!  I tapped 50 cones and collected only 5 spiders but 4 species.  That's a high maturity rate for a cone sample!  Besides another L. mercedes this sample contained a Micaria pulicaria, which we didn't find in any other microhabitat this trip.

Read Rod's trip narrative here.

The rock walls of Union Creek gorge were a good place to find Callobius
My camera barely captured the subtle lilac sheen on the abdomen of
this female Callobius.

Monday, July 18, 2016

13-July-2016 Friends Landing, Washington

Site location map. Click to enlarge.
It's getting late in the dry season for low elevation collecting, but Rod Crawford had a site in mind in Montesano where he hoped the coastal influence had maintained moister habitats.  He was right!  The forest understory around Friends Landing, which lies in the Chehalis River floodplain, was still lush and green.  A well-maintained paved trail, boardwalk and footbridge around Lake Quigg made the hike from the trailhead to the west end of the lake a breeze.  Looking at aerial photos, Rod had spotted a few conifers in the deciduous forest near the lake outlet, so we agreed it would be a good place to start collecting.

Lake Quigg Outlet

Rod photographing Sitka spruce trunk
Fallen Sitka spruce cones
The conifers turned out to be Sitka spruce (Picea sitchensis).  I'd only tapped Sitka spruce cones once before, in a dry meadow on Lummi Island.  In contrast, the spruce trees at Lake Quigg were in a tidal swamp, each tree creating its own tiny island.  The only fallen cones available to tap were those that had escaped "tidal cleansing" by falling onto these tiny islands.  I managed to find and tap only 46 cones.  Many cones were still loaded with seeds, meaning there wasn't room for spiders in the cone scale pockets, so I wasn't too surprised to collect only two spiders from the lot.  One was a juvenile linyphiid, the other a penultimate male Xysticus (Thomisidae).

Theridion varians female with
egg sacs and spiderlings
Footbridge over Lake Quigg outlet
While Rod sifted moss and leaf litter, I turned my attention to footbridge railings and found numerous female Theridion varians (Theridiidae) with egg sacs on the underside of the top rail.  Back in June Rod collected an atypically colored T. varians (photo here) on the banks of the Nisqually River.  The females I collected from the Quigg Lake footbridge presented yet another color morph.  Just another reminder that you can't necessarily rely on coloration when identifying spiders.  Theridion varians is a tiny species, so I didn't see the details of what I was photographing at Lake Quigg until I downloaded the images.  As it turned out, I photographed not only a female and egg sacs, but a whole herd of spiderlings as well!

Campground

Male Poecilochroa
Moving on to the very tidy campground on the south shore of the lake, I would have stepped on this male Poecilochroa (probably) montana (Gnaphosidae) had he not moved.  Presumably the species didn't evolve that coloration to be cryptic on asphalt, but for sure they are.

Douglas-firs were second cone source
A row of Douglas-firs (Pseudotsuga menziesii) growing between the campground office and the tent camping area provided me with another opportunity to tap fallen cones.  Despite the general moist lushness of the area, the scales on these cones were completely open.  A pleasant surprise!  Yet the spider sample I tapped from them was another yawner.  From 50 tapped cones I collected only 2 spiders: 1 male and 1 juvenile Tenuiphantes tenuis (Linyphiidae).

Read Rod's take on the day here!

Young swallows have almost outgrown their nest
under the eaves of a fishing shelter

A female Lariniodes patagiatus in her daytime retreat
on the outside of an outhouse
Lariniodes patagiatus female