Once, while exploring the back roads of Delaware with some educators, I asked about lakes, and received, what seemed at the time, an odd reply: "No such thing here! We only have whale wallows." I had the same dumb look on my face years later in southern New Jersey when I was introduced to similar ephemeral wetlands, known locally as spongs and pingos. These are peculiar, semi-aquatic depressions that are found in the Pine Barrens and are unique to the Atlantic Coastal Plain.
Presumably most once were ponds, but as is the nature of wetlands, they have gradually filled in with organic material. Now they are typically shrubby wetlands encircled by plants familiar to most of us, like high-bush blueberry and sheep laurel, and sometimes supporting some unfamiliar and globally-rare species of grasses, sedges and even orchids. Pleistocene glaciers and Arctic conditions crept south to the edge of what is now the Pine Barrens, and these vernal pools are thought to have formed from wind blowouts or as the geologist would describe them, peri-glacial thaw basins.
At least that's the theory. Farther south, similar wetlands are called bays, Carolina bays, or in Delaware, Delmarva bays, to illustrate their distinctiveness in different regions. If you enjoy wetlands, word origins and weirdness, then Carolina bays are right up your alley.
Few wetland terms are uniform in the U.S. or elsewhere and they tend to acquire local labels. For example, in his research extracting antibiotics from wetlands, the eminent Dr. Waxman of Rutgers University, uncovered 90 English terms for what he called peatlands. (Which some authors today would like to simply lump altogether as moors.). Researching the literature on wetlands is almost as entertaining as going out and exploring them.
Spread almost a thousand miles along the coastal plain from
New Jersey to the Carolinas,
where they were first studied, there may be close to a half-million
of these peculiar potholes. The term bay, like many ecological
emblems, comes from their distinctive vegetation. In the bays
of the Carolinas, you can expect to find these low spots dominated
by evergreens like the loblolly pine and the red bay, a laurel.
At their northern limits in the Middle Atlantic, they tend to
support deciduous facultative wetland trees like sweet gum, tupelo,
red maple, and our reluctantly-deciduous magnolia, the sweet bay.
Carolina or Delmarva bays (Or whale wallows, pocosins, coastal
plain ponds,
or whatever the locals call them) are certainly puzzling. Most
are less than an acre in size, elliptical in shape, oriented southeast-to-northwest,
and often have a sandy berm on the southeast side. Another feature
they share is an alarming concentration of threatened plants and
animals that rely on these isolated wetlands for the most critical
stage in their life cycle, reproduction.
Most ephemeral wetlands and ponds like these bays are sensitive areas harboring susceptible species with strict habitat requirements - amphibians and invertebrates that need to raise young away from fishes, and plants with an intolerance of habitat alteration and an inability to compete with many invasive or alien species.
Speaking of aliens, there is no shortage of theories about the origin of bays over 10, 000 years ago; and one of many is extraterrestrial - a massive meteor shower or exploding comet. Other speculation includes: Ice Age wind scouring or frost heaving; depressions formed by artesian springs; "subterranean forces" (Whatever that means); basin-to-bay-to-stream drainage cycles (A geomorphic cycle of formation that Lorraine Fleming describes as the geologist's water table-sinkhole-lacustrine-aeolian theory); excavation by schools of spawning fishes or tidal action during periods of raised sea level; stranded icebergs; and of course my favorite, the wallowing of whales.
This year, we finally found an occasion to venture out on my quest for some answers about whale wallows. Maps, local advice and an eye for plants that prefer wet areas, are essential for finding these sites, so I contacted my naturalist friends at the Delaware Nature Society (The same culprits who first befuddled me about whale wallows) and the Delaware Natural Heritage Program, which keeps an eye on these delicate places. All were very helpful and proud of their state's wetland treasures.
First the bad news: Two thirds of the 1,500 sites in Delaware have been altered or destroyed by human activities. Many exist on private property and farmers cut the valuable timber or filled many of these low areas in their fields. Development and changing water quality also take a toll, especially on the invertebrates, salamanders and frogs that rely on these isolated wetlands. The good news is, there are a number of preserved sites on public lands, and they are identified on maps.
If you wish to explore Delaware's freshwater (palustrine) wetland environments, naturalists direct you to Lums Pond State Park along the Chesapeake and Delaware Canal, which is designated for public access. A pond here called the whale wallow has a boardwalk and interpretive signs, and this is a great place to start.
"South of the Canal" -- as they say in Delaware (The rural part of the state -- at least until the next real estate boom.), we headed for Blackbird State Forest, a managed forest of planted pines and noteworthy stands of oak, beech and hickory. It is also the site of the Tyabout Tract, and one of the better known Carolina bays (Which, as you head south, are also known colloquially as round ponds, black bottoms, loblollies and sinkholes!).
It's a great place to get lost in the woods and that's exactly what we did searching the trails for these enigmatic wetlands. This was a drought year, but with a little detective work, we followed some botanical clues to wetland soils: princess or ground pine (Lycopodium), red maple, pepperbush, sweet bay, cattails, rushes and possum-apple. Because few plants are tolerant of fluctuating water levels, a fringe of rugged buttonbush surrounding an herbaceous central area is a good indicator of the high-water mark of these types of wetlands during the wet periods. Also, it is not unusual to find wind-throws and standing dead trees near wetlands, and fittingly, we could hear the distinctive hoarse broadcasts of a red-bellied woodpecker staking out its claim among them.
Since the campground was empty and we were visiting after the hunting season (Another activity encouraged in this multiple-use area and testimony to the wildlife value of these spots), we had the whole 6400 acres to ourselves. The quiet forest was alive with the soft yank-yank call of white-breasted nuthatches; surprisingly, the most abundant forest bird this day.
Heading back through the dry upland forest we discovered two more gems. Searching for insects in the deep furrows of the shagbarks that it also relies on for a nest site, we were delighted to spot our first brown creeper of the year. And high overhead, on the topmost branches of a tall oak, a growth of mistletoe -- the perfect finale to our mid-winter hike.
Delaware is not a large state, but winter days are short, and following directions that a colleague provided to another intriguing site, we raced back north searching for one last bay that was reported years ago as "threatened." We sped through the town of Blackbird and the great wintering flocks of crackles, cowbirds, starlings and red-wings demonstrating their graceful afternoon murmurations across the farmlands, with barely enough time to tap the brakes at Bailey's Seafood Store ("Whole muskrat - $2.95") before crossing over the canal and heading North towards Wilmington.
Working our way down the Old Baltimore Pike near the Maryland border, we followed our primitive map (With warnings regarding "the rapid development of the general area.") to what turned out to be (No surprise here!) a new housing development. Here we hoped to find a place described as an ancient watering hole, said to be frequented in prehistoric times by Indians and the game they hunted.
Confident that we were becoming world-authorities on bays and
all types of wetlands, we entered the development, managing to
drive right past our objective and several other ephemeral wetlands
without noticing them. Our oversight illustrates the problem of
identifying and protecting these small, isolated wetlands.
It's a pleasant community, built along serpentine streets with
names like Preakness Run and Thunder Gulch, that predictably,
have nothing to do with the site's history or geography. However
it was soon apparent that they weave their way around many isolated
wetlands. The immaculate green lawns reminded me of golf fairways
mown right up to a curving, wetland "rough."
We were a little disappointing, although not surprised in this region of rapid growth; but we elected to explore it anyway because, after all, it has wetlands. With the helpful advice of some residents (Who just happened to have their wetlands delineation survey map handy), we marched into this suburban wilderness; a half acre cul-de-sac of a swamp, right across their street.
All wetlands are interesting and important, and despite being encircled by this All-American suburban street, the inroads of a playground, gazebo and the requisite plush carpet of wood chips (The homeowner's final foray against soggy soil), this remains a neat wet forest. It's dominated by tupelo, sweet gum, oak and red maple and there is also the predictable under-story of blueberry, pepperbush, and holly helping to isolate the open water area and patches of bulrush. We were jealous. If you live in Suburbia, what could be better than viewing a wetland from your front porch?
I asked our new friends whether this was the local Carolina
bay, and although coincidentally, she had visited one on a geology
field trip in college, neither was aware of one locally.
I used the occasion to ask a few more questions to gauge the wellbeing
of the place. "The Mosquito Commission takes care of the
site." (That's not always good news.) "We like it. The
wetlands prevent others from building behind us." (Justice
William Douglas once defined an environmentalist as: "The
last person to move into town." That's a given.) "The
soil stays wet, even in a dry year like this." (That's certainly
not bad news for amphibians and other wetland-dependent creatures!)
The homes are sewered, but regrettably, I forgot to ask if they had basements; although they appeared to be on slabs. (A wetlands specialist once pointed to a development where a similar palustrine forest was being urbanized in Pennsylvania and told me: "Those homeowners will now have a life-long hobby …trying to keep their basements dry!")
Apprehensively, I asked the fateful question… "Do you hear treefrogs calling in the spring?" Blank stares… Quickly our expedition degenerates down to this: We're standing with complete strangers on an unfamiliar street off Dixie Road in Delaware; suffering through quips about the Mason-Dixon Line ("It's what separates y'all from youse!")… imitating frog calls…
"A harsh, duck-like clacking? " (This should be a given since the Wood Frog ranges farther north than any other North American reptile or amphibian.) "Definitely not."
"A short snore; like a finger running across a comb?"
(The Pickerel frog is uncommon on the coastal plain south of Staten
Island, but it was worth a try.)
"No."
"A long rattle or squeak; like rubbing a balloon with
your finger?" (The Leopard or "Meadow" frog,
with the broadest range across America, should be here.)
"No."
"A melodious, bird-like trill?" (Gray treefrog)
"Maybe…" (Things were looking up!) "This woodland
gnome starts its lonely, lovely trill as the sun lowers and evening
breezes start their patrols."(Henry Collins)
"A banjo-like twang?" (The Green frog is ubiquitous
in swamps and streams.) "Oh yes!"
"High pitched peeps - jingling sleigh bells?"
(Spring Peepers seem to be the most enduring of the tree frogs.)
"You mean the ones that climb up the patio door in the spring?"
This was definitely good news. Of these little marsh sprites the
poet wrote:"The pipes of Pan in elfin chorus ringing….Bring
sweet dreams of youth and love and spring." (Henry Collins)
But the day was almost done and we still hadn't found our main objective. It was time to seek out a real authority on the area, and with the exception of fishermen, no one is more knowledgeable about water bodies than kids on bicycles. They didn't know or care about vernal pools or anything called a Carolina bay, so I pulled my last rabbit out of the hat… "I've heard there's a bottomless sinkhole around here…"
We were immediately directed to the local mystery spot, a sinkhole if there ever was one. It is a small but deep, perfectly circular, crater-like pool of dark water, surrounded by trees that should have tipped us off earlier; red maples and that ever-so appropriately named swamp tree, the Pin oak - Quercus palustris.
This was our most anticlimactic moment so far. I wasn't expecting the La Brea Tar Pits, but there are no signs or fences; and the lawns are mown right up to the tree line. Ruthless exotics, Asiatic multiflora rose and bittersweet vines, are invading the edges.
It took a good deal of imagination to picture the prairies of post-glacial Delaware, the complement of mammoths, musk oxen and camels that may have visited here, and the Paleo-Indian hunters that pursued them. At least it wasn't filled with trash and tires, so hopefully it is still useful to wildlife. I'd like to revisit it on some April evening during a torrential rainstorm to see what creeps and leaps into it to croak, croon and couple.
Uphill from the sinkhole we noticed patches of cranberry, which led us to our last wetland; a small depression in the forest - a classic woodland vernal pool. Except during a rainy Spring, most of us would never dream this could be a wetland. There is a fringe of ground pine, and tupelo trees - each with a customary skirt of moss on the trunk; all growing in a dry, powdery rusty-colored dirt. The vegetation, oxidized soil and accumulation of leaf litter, are clues that this spot is flooded only temporarily during the year.
We turned over a few rotted logs looking for red-backed salamanders, the most common vertebrate of the Eastern deciduous forest, but to no avail. They are just one of many species that must wait a year or even half-a-decade for these disappearing wetlands to recharge with water and be suitable breeding sites.
Driving home we passed many new housing developments; each with their own detention basins for rainwater that once filled vernal pools, swamps, bays and other inconspicuous or intermittent wetlands. None of them are clear, dark or mysterious like the natural waters we'd just explored, and many are green from the filamentous algae thriving on fertilizer running off the surrounding acres of lawn.
After our various encounters, I realize now that most people "like" wetlands and "understand" their importance, but it has to be on human terms; neat, manageable, engineered if necessary, and not interfering with our lifestyles. Unfortunately for us and the creatures that rely on these delicate and enigmatic ecosystems, this is something wetlands can never be.
Further reading:
1. Lorraine Fleming. Delaware's Outstanding Natural Areas and
Their Preservation. Delaware Nature Society. Hockessin, Delaware
19707
2. Outdoor Delaware. Spring, 1993
3. H.S. Savage, Jr., The Mysterious Carolina Bays. University
of South Carolina Press
4. Henry H. Collins, Field Guide to American Wildlife, 1959. Harper
and Brothers Publishing