Category: In the Field

I had a couple of hours between events in Bloomsburg to take a ramble through Nescopeck State Park. The traces of earlier uses of this land are easy to read: the Wood Frog Way Loop trail is almost rectilinear. There were many more annoying dipterans than charismatic lepidopterans to be found on this cloudy Saturday morning. But hunting in the park has apparently kept the deer population in check, and hence the understory looks to be in good shape. And I found a couple patches of healthy-looking Eastern Hemlocks (Tsuga canadensis), hopefully adelgid-free.

To break in a new pair of boots, I took an easy loop hike on the blue blazes around the battlefield of First Bull Run. The breezes were strong, and it was midday, but there were a few butterflies flying. I turned up something I didn’t remember from last year—Common Wood Nymph (Cercyonis pegala)—as well as something that turned out to be, upon checking my photos later, an animal I’ve never put on my list before, Pipevine Swallowtail (Battus philenor). I think I’ve probably seen this guy before, but I’ve been put off by one of the photos of the dorsal side in Glassberg’s book. The ID key, it seems, is actually the single row of orange spots on the ventral side of the hindwing.

The bridge over Bull Run was once a prized strategic objective. Now, not even the nesting swallows are interested in it; they prefer the U.S. 29 bridge just downstream.

The trail gets a lot of noise from the roads and a winery just across the run, but it crosses through a lot of woods and can be quite pleasant.

The Carter family cemetery is completely enclosed by a stone wall built from the ruins of Pittsylvania, the manor house. The graves within are not individually marked. The last interment was done in 1903.

One of the simpler assignments for my current class in freshwater ecosystems was to visit the falls of the Northwest Branch (and have a picture taken to prove it).

This reach of the river is wild and urbanized at the same time. The trail is a short stumble down from a parking lot on Colesville Road. This is the site of Burnt Mills (ooh, the Internet Archive has an interesting book from 1931 about the history of the flour mill that was here). The riverborne trash is hard to overlook, and especially around the parking lot, the non-native invasive plants are pretty aggressive. Nevertheless, I found a few bits of Rattlesnake Weed (Hieracium venosum) growing around the rocks. Leta and I scrambled for a couple hundred yards downstream before turning back. I showed her an Acadian Flycatcher making sallies to a pool.

On the other side of Colesville Road, the river is held back by a dam and spillway. On this flat bit of trail, we found two Five-lined Skinks (Eumeces fasciatus): a juvenile with the familiar blue tail and a much-larger adult male with indistinguishable lines, orange-red in the head, and a truncated tail.

Leta chatted with one of the fishermen, who said that sometimes he took bream from the river. I think that we would know these as sunfish.

Today’s report for nesting activity, abridged and annotated:

A much greener park than 5 weeks ago, and most of our boxes have hatched! We have 8 (at least partially) successful nests, and one failed drop/dump nest in box #4. Box #13 was in the process of hatching when we got there; the Wood Duck hen flushed and showed a somewhat unexpected distraction display. We closed up the box quickly and backed off; we will get a shell count next time. Box #84 may also be in the process of hatching. Box #60, hatched out, at right.

In the vicinity of box #62, we had unaided eye views of a male Prothonotary Warbler (Protonotoria citrea), vocalizing “sweet-sweet” and checking out some natural holes in a snag. Of course, this the spot where we’d maintained warbler boxes for a few years–until this season.

We’ll have another work day in June, to count #13 and #84 and two more boxes that haven’t yet hatched. Box #62, still unhatched, at left.

Water gauge reading: 1.64

This beaver-cropped Sweetgum tree reminds me of Barnett Newman’s Broken Obelisk. A lot.

Our field trip for Jai Cole’s Freshwater Ecosystems class visited the Left Fork of the Paint Branch, on the site of the former Maydale Nature Center. The site is part of the Upper Paint Branch Special Protection Area, and the stream was the target of recently completed restoration work. We focused on the restoration work, and also performed a classroom exercise-level habitat assessment.

The centerpiece of the restoration is this 100-meter reach. You’re looking upstream and roughly northwest, standing on a bridge that provides access to the area. Out of frame to the right is a small parking lot. The point of the project was to replace a series of notched logs that channelled the stream as it drops from a weir (the flat water just visible in the background) (which maintains water supply for a pair of ponds on the property) and flows under the bridge; the problem with the logs was they they weren’t designed to allow fish passage. (Brown Trout is a naturalized breeder in the watershed.) The project replaced the logs with a series of arcing rock structures (called “cross-veins” in the local engineering parlance), each with a gentler drop and a plunge pool downstream. The pools give fish swimming upstream enough elbow room to get up speed to jump and surmount the rock barrier. Notice how the top of each arc of stones drops a few inches at the center: that’s where we want the most water to flow. A vertical plane through a watercourse passes through the point of maximum flow and the deepest part of the channel, which is called the thalweg, and in this case we want the thalweg to remain where it is.

From elsewhere on the stream, here’s a closeup (albeit with a lot of glare) of an arced cross-vein on the right and a straight-line weir on the left. Water flow is right to left, and the weir maintains the pool downstream of the cross-vein. Again, notice that, at this level of flow, the stones of the cross-vein near each bank are high and dry, and the stones in the center have the most flow over them.

Stephanie Mason led another nature hike yesterday, this time at an elevation considerably higher than three weeks ago. We covered about 5 miles along the Appalachian Trail and side trails, from Stony Man to Jewel Hollow.

We got some nice looks at high-elevation tree specialists for our region, like Balsam Fir (Abies balsamea), Red Spruce (Picea rubens), and the glossy-barked Yellow Birch (Betula alleghaniensis). Perhaps owing to the higher elevations around Stony Man (4011 feet), the Eastern Hemlock (Tsuga canadensis) trees in this patch look pretty healthy and untouched by the adelgids.

Closer to the ground, spring ephemerals were abundant—Wild Pink, Moss Phlox, cinquefoil, bluets, many violets, Wood Anemone, waterleaf, Star Chickweed. I picked up one butterfly for my list, Falcate Orangetip (Anthocharis midea). Among the birds, the best was a bird from my “renewal” list of lifers that I haven’t seen in a long time: Veery (Catharus fuscescens). Good, multiple looks at Chestnut-sided Warbler (and we could point them out to a party of passing hikers) and American Redstart.

We climbed about 300 feet, then dropped down and ended about 300 feet below our starting point. We hit Stony Man early enough in the day (before noon) that the traffic was not too bad.

Frogging by ear tips, derived from yesterday’s walk to Calvert Cliffs on the Western Shore of Chesapeake Bay with Stephanie Mason: Gray Tree Frog (Hyla versicolor and H. chrysoscelis) sounds something like the ratchet on a retractable dog leash, while the irregular clicking sound of Cricket Frog (Acris sp.) resembles those annoying magnetic balls that my colleague Dylan likes to play with.

Once again, we saw elvers shimmying their way up Grays Creek. Eels (the young are elvers) are catadromous, that is they migrate downstream from fresh to salt water to breed then die, unlike the better known anadromous migrants (like salmon) that swim upstream to freshwater spawning grounds.

Also in the watercourse, we saw many Water Boatmen (Corixidae) sculling about.

Stephanie calls the 5-inch-long Fence Lizard (Sceloporus undulatus) our local iguana, since it is in the same superfamily as the big guys of the southwest.

Trees were late leafing out (this is one of my favorite local species, Carpinus caroliniana, just opening up), so the birding was good. We heard or saw nearly three dozen species, and found two nests being built by Blue-gray Gnatcatchers (Polioptila caeruluea). The gnatcatchers showed some variety in vocalizations; one colloquy between two birds sounded like a couple of mockingbirds after too much espresso. My good bird was a fairly common species that I just don’t see very often, Yellow-throated Warbler (Dendroica dominica).

Margaret Chatham led a wildflower walk at the Nature Conservancy’s Fraser Preserve for VNPS. Spring Beauty was plenteous, but (as you would expect, given the everlasting winter we had) many bloomers were weeks behind schedule. Margaret showed us one example of Harbinger-of-Spring (Erigenia bulbosa) (very difficult to image properly); Purple Cress (Cardamine douglassii) was in various states of opening into flower; some Trout Lilies (Erythronium americanum) in a sheltered wet spot were in flower. But the Dutchman’s Breeches (Dicentra cucullaria) and Cutleaf Toothwort (Cardamine concatenata) really hadn’t gotten started yet.

Down along the pipeline easement, the Poison Hemlock was nothing but basal leaves, nothing at all like the towering plant I saw just 49 weeks ago.

We found some early flying Spring Azure and Mourning Cloak butterflies. I was happy because we found three single Bloodroot blooms (Sanguinaria canadensis), widely scattered—this has been sort of a nemesis plant for me.

Reports from the nest box team for the past two Sundays:

We have evidence of roosting in 7 of the boxes, but at this point we have nests in only 2. Box #3 is incubating, so we can skip checking that one next week. With Steve’s help, we replaced box #6 this afternoon.

Notable birds for 9 March: Northern Pintail, Northern Shoveler, Gadwall, Green-winged Teal, Ring-necked Duck, Bufflehead, American Coot

We found a dead Barred Owl along Barnyard Run; we conveyed the specimen to park staff.

Notable birds for 16 March: Northern Pintail, Northern Shoveler, Gadwall, Green-winged Teal, Ring-necked Duck, Bufflehead, Hooded Merganser, Wood Duck, Eastern Bluebird, Eastern Phoebe, Tree Swallow (afternoon)

Water gauge readings: 1.86 (9 March), 1.50 (16 March)

Much of the snow has melted and packed down, but much remains. The blacktop trail and stream are clear, but much of Lake Audubon is iced over. Hence my most numerous bird was not the $100 Jeopardy! answer, Canada Goose, but rather Red-winged Blackbird. I had reached the footbridge and was ready to turn around when one of the rather reliable Red-shouldered Hawks (Buteo lineatus) of these woods made an appearance.

Best bird of the day was a Hermit Thrush (Catharus guttatus) watering in a puddle of meltwater. A respectable 22+ species count. Bonus mammal: a Red Fox trotting across the frozen surface of the lake.

Saturday, Paula DePriest led a workshop of mostly frozen participants to Carderock on the Maryland side of the river. Our subject: rock and tree lichens (the soil lichens being inaccessible due to snow cover). Soil, rock, or bark is only the substrate (although certain species do have a preference); the lichen gets no nourishment from it. In all cases, sugars are generated by algae held in the body (thallus) of the lichen, which comprises a fungus. Depending on your point of view, the alga is a captive of the fungus or (Dr. DePriest’s preference) is domesticated by the fungus.

Rocks in this area often are commonly home to a Mid-Atlantic specialty, Flavoparmelia baltimorensis. It’s the pale yellow-green (yellow to a lichenologist) lichen at the lower left of this badly-focused image, along with Lepraria sp. at the right and Pertusaria sp. at the left.

The olive-ish color and black specks of Porpidia sp. are fairly easy to learn. This individual is about 4cm across, as you can see from the scale card.

The relatively bright yellow of Candelariella sp. is also easy to find. This crustose lichen goes by the common name of Egg Yolk Lichen.

This Punctelia rudecta, a foliose lichen, was found on bark. The tiny punctuations in the lichen’s thallus, and the dark isidia surrounding them, don’t read in this image.

The good news is that there are about three dozen taxa of lichens of interest in the D.C. area. You can write a key (as Dr. DePriest has) to all of them that takes up only two pages. The bad news is that you need at least a hand lens to apply the key.

Construction is complete for the wetlands restoration project at Huntley Meadows Park! Some additional planting and trail work remains, but the period of monitoring and maintaining has begun.

Park manager Kevin Munroe led a special-access “backstage” mini-tour of the dam and water control structure for a group of volunteer staff on Saturday. Working backwards, as it were, this is a view of the outflow into Barnyard Run. As you can see, everything is still rather raw and artificial looking. The sine wave-like curves of this stream haven’t yet been naturalized to a messier state. Kevin says that the park will take an “adaptive management” approach to the project. If the beavers drag one log across this watercourse (beavers abhor moving water), it won’t necessarily be removed.

The water control structure itself is disguised as an observation platform, via the addition of the protective railing. At left, a view upstream, looking at the main wetland. At right, water flows right to left through the baffles and chambers of the structure, through a buried concrete culvert, into the outflow.

Manholes for easy (depending on what you think “easy” means) access to the interior of the structure, for cleaning out debris.

The observation platform itself, accessible from the South Kings Highway side of the park via the hike-bike trail and a new stone dust trail, is obscured from view from the main observation tower and boardwalk by an artificial knoll. Even though it’s possible to access the dam and water control structure from the boardwalk side of the park, this is discouraged by management, for a number of reasons I won’t go into here. But making the platform and tower mutually invisible makes the crossing less tempting.

The working part of the dam is an interlocking wall of vinyl sheet pilings. All you can see of the wall is the plastic strip that runs along the top, the straight white line in this image. From an engineering and hydrology standpoint, the earthen berm enclosing the dam on both sides is unnecessary: it’s purely for naturalization. (Cf. the unsheathed impoundment walls that you see on many National Wildlife Refuges.) The ground has been planted with native grasses and vines, and the hope is that by summer the dam and its berm will be covered with chest-high grass and access-dissuading, thorny greenbrier and raspberry canes. Something to check back on in a few months.

Something else to look for in the future: A few trees have been caged in metal fabric to prevent beavers from taking them down—there’s a Red Maple right next to the “phoebe bridge.” Soon, you will see more trees thus caged, but these are trees that park staff understand will be killed by inundation as water from the project finds its new level. These will become snags, standing dead trees that serve as habitat for all sorts of organisms, and are thus valued by foresters.

There’s a great photoset of work-in-progress images curated by the Park Authority. In particular, you can see the interlocking sheets that make up the dam, before they were covered in dirt.