Crossing Delaware Bay
by Dave Grant
"Nothing is rich but the inexhaustible wealth of nature.
She shows us only surfaces, but she is a million fathoms deep."
Ralph Waldo Emerson

Most of what I have learned about Delaware Bay I associate with crossing it on the Cape May-Lewes Ferry to visit Cape Henlopen and the University of Delaware's marine lab. The 17-mile journey lasts just long enough to clear your mind of most of your worries, and fill it with wonder for this great body of water.

Fall: Falcons and fair weather
If I have a favorite season to cross Delaware Bay, it's the fall. As we depart from the Cape May Canal, I always position myself at the stern for two important diversions. First, it's crucial to keep one eye out for the natural history sightings off the port side of the vessel. Second, it's entertaining to watch well-wishers off the starboard side.

Heavier birds migrating south to Cape May find their route blocked by the bay, so most make a seventy-mile detour north and west around the it (Ornithologists call it a reverse migration.), taking advantage of thermals for soaring (If you are a hawk) and trees for resting (If you are a blue jay.). It takes more than three times the energy for a bird to fly, as opposed to soaring on updrafts, so if you do the math, the energy formula works out in the bird's favor, especially factoring in afternoon Southeast headwinds off the ocean, hungry gulls, and the risk of drowning. Of course if you don't like the math, the birds' behavior validates this too. Regardless, when the sea breeze kicks up at Cape May, the airspace above the ferry dock fills with vultures, "sharp-shins" and red-tailed hawks and it often becomes the "hawk-watch capital" of the East.

At the same time, it is also important to observe the action on the starboard side of the ferry. If I were mischievous, I would simply wave back to the sightseers on the canal jetty, rather than point to the ferry wake bearing down on them. Fishermen who habituate the spot know instinctively to move up higher on the rocks when the ferry departs, because when the conditions are right, the wake sets up like a bore and the unmindful get a hands-on lesson in physical oceanography -- a drenching from the thick and powerful sweep of water, moments after the boat passes.

Entering the bay means it's time to get serious about birding and this requires constant scanning of the horizon. Most of the action is usually on the second half of the cruise, but there is plenty to look for as we head south; the Cape May lighthouse, the old WWI cement boat placed as shore protection off Sunset Beach, and occasionally, hanging around it, the last migrating tern of the season. Typically it's a royal or more likely, a Forster's tern in its distinctive bandit-faced winter plumage.

Wind is your enemy on the bay after storm fronts pass and because of the long fetch to the Northwest, the strong dry gales from that direction kick up a significant chop. An October excursion I look forward to is Coast Day in Lewes; a grand celebration of Delaware's waters. Several times, on the heel of a passing cold front, I've taken a busload of New Jersey festival-goers across on the morning sailing; many of them groaning about the long bus ride, and the driver, and whatever else isn't just perfect when we depart at the crack-of-dawn. Fortunately for landlubbers, once we sail, it is a following sea for much of the south-bound voyage or, in spite of the size of the ferry, many more passengers would get that grim "Must buy the boat from the captain to turn around…" stare.

In October it is also not unusual to have a good ground swell from some distant hurricane adding a long period beat to the mix, and this seems most evident in the ship channel where the water is 150-feet deep. Every so often in the middle of the bay, when the five-second chop complements the 10-15 second swell, we get a shutter that has everyone hoping they followed the captain's instructions to set their car's emergency brake and turn off the alarm.

From the lowest deck the view off the stern is awesome as a hundred gulls jockey for position to catch a free ride on the wave of air that the boat pushes ahead, and to dive into the clashing wake and chop to snatch up whatever the propellers kick up. As my bus passengers, many of whom have found themselves suddenly much more appreciative of highway travel, come up to me with suggestions that the three-hour drive around the bay to get home isn't such a bad idea after all, I find myself smiling, enjoying the wildness of it even more, and humming to myself Richard Rodger's tango Beneath the Southern Cross - that theme from the Navy's Victory At Sea classics.

In fall, the bay is still rich with summer life and in the midst of a mass invasion by northern sea ducks, cormorants and other waterbirds. Most likely, you will see long lines of dark scoters undulating over the swells, low-flying flocks of brant and high flights of cormorants and; but it is also possible to see a pelican lingering on its trip south, fishing along with another arrival, its northern cousin the gannet, diving on a school of fishes.

Paradoxically, it's the smallest birds that seem to take the biggest risk and sally forth, migrating out across the bay. Halfway across, songbirds become tired or distracted by the ferry and start to get drawn in behind it. Now, low on the deck with us, they can't see land, have trouble taking off against the pulse of air enveloping the ferry, and are in a real fix. Their variety reflects what is migrating through at the time -- or at least what I can identify from colors, silhouettes or obvious features; warblers: yellow-rumps, redstarts and the like.

If you are alert you will see falcons over the bay. The high-flyers are likely to be kestrels and these smallest of the falcons seem to be simply making the best of the short-cut and hurrying across, although once I observed one of these agile hunters take a big blue darner dragonfly. (One of many migrating insects that also cross the bay.) Peregrines are harder to spot, racing low over the water at the altitude of their preferred prey, migrating shorebirds. Anyplace is their hunting ground, and I've seen them spilling white feathers, plucking their catch as they race along (Talk about fast food!). Merlins are more likely to be buzzing those hapless warblers near the boat and taking them as we approach the shoreline, since they are large enough to carry their kill to a resting-place. Along with kestrels, they are a regular fall feature around the Lewes dock and are a sensational sight, dive-bombing on exhausted arrivals.

Winter: Wandering and wondering
Winter is not always the rough crossing one might anticipate. It is sometimes windless and flat-calm - as the boaters say. There are always gannets and gulls to amuse you (I spotted my "first" lesser black-backed gull from the MV Cape Henlopen), and the slow bird-watching and low sun reflecting its warmth off the water give you more time for reflection about the bay. Also, the ferry is one of only two places I know of locally where you can watch the sun set over water and get a glimpse of the green flash, so I try to schedule my return trip late in the day.

The tide table in the tourist booklet indicates that tide crests in Cape May before Lewes, and this gets me thinking and scratching in my notebook. The textbook model of estuaries says that because of Coriolis Effect, the tide sloshes to the right around the basin in a counter-clockwise direction in the Northern Hemisphere. Does the rotation of the earth explain this tidal differential? I know that Delaware Bay is deep in the ship channel, but the average is closer to thirty feet, so the tide is forced to travel like a shallow-water wave progressing up-river past Wilmington and Philadelphia, to the fall-line at Trenton. I recall the formula for the speed of a shallow-water wave (The square root of Gravity times Depth). I know the length of the bay's shoreline is 128 miles (Only fifty five of which is in Delaware - which I like to point out to my colleagues while I'm over there.). I begin to calculate the speed of that amphidromic wave as it works its way around the bay to see if that will account for the time lag; and after more than a few minutes of scratching my head, conclude that I should have been more alert in Physical Oceanography class (and to the jaeger that just flew past the ferry).

To geographers (And those who know their Spanish), Delaware Bay is a Ria-type estuary - a flooded river valley. For comparison, the smaller Hudson River/Raritan Bay system is far enough north that the Palisades region is glacially scoured, and it is sometimes called a fjord-like estuary. South of us is the granddaddy of Ria systems - the Chesapeake, which is five times larger than Delaware Bay.

Oceanographers describe estuaries according to what's happening in the water, and Delaware Bay is a partially-mixed system. In the winter and spring when the land runoff is greatest, I look down and imagine freshwater and the nutrients washed from the land flowing over the denser saltwater, producing a stratified or layered system. In summer and fall, the bay becomes more of a mixed estuary like the lower end of Raritan Bay; and in any location, the salinity is similar from the surface to the bottom.

Check out the charts posted on the ferry, and study the geography of the bay. The freshwater-saltwater interface of the Delaware system is most pronounced near the Smyrna River-Salem transect. Areas like this tend to be the most productive nurseries in estuaries -- not the sort of place an ecologist would dream of placing factories, refineries and power plants that use or abuse large amounts of water -- which of course is just where they all begin to crowd the shoreline. On cold days, if you scan the horizon to the Northwest, you can see the massive plume of water vapor from river water that has been drawn into the cooling tower at the Salem Nuclear plant. The process is said to kill billions of fishes each year. Fortunately the dynamics of the estuarine system and the stamina of the creatures that live here keep the river flourishing.

The estuarine drainage area of the bay is smaller than the Chesapeake or Hudson river systems, but there is enough freshwater inflow from the watershed to produce a flushing time of 2-3 months. This and the remaining wetlands (Since Colonial times, Delaware, Pennsylvania and New Jersey have lost, respectively, 73, 56 and 39 percent of their original acreage.) maintain the bay's water quality and help it recover from the poor conditions near upstream cities and industry.

Spring: Ice breakers and ospreys
Spring is the cruelest season for the naturalist crossing the bay. The ocean has not warmed, so when there is a sea-breeze it is surprisingly cold and clammy out on the water. The bay is discolored from plankton and runoff, especially on the Delaware side (That Coriolis Effect again?), and the multitude of large creatures in the water is not yet apparent. However, as always, the seabirds alert us to the presence of fishes. Arguably the most dramatic bird watching experience along our coast is the great assemblage of gannets that follows plankton-eating herring into the bay. Battling each other and black-backed gulls, gannets plunge like javelins into the ferry wake and quickly resurface, holding in their bill prey that looks impossibly large to swallow.

In Maine, people compare a person with a big appetite to the gannet, and it's astonishing to watch these splendid birds in action off the stern, gulping down foot-long fishes while being mobbed by other birds.
According to Witmer Stone, that great observer of Cape May's avifauna, your best bet for seeing large numbers of them is in March and April, and I certainly agree with that. The brilliant white and black pattern and the unmistakable "perfect cross silhouette" of a gannet before it plummets from fifty feet or more catches your eye from a great distance and probably signals other birds too. There never seems to be only one bird diving for food and a whole flock gathers in an instant as soon as the first fish is caught.

Arthur C. Bent wrote of them: "Over the unlucky school of fish is a bewildering maze of soaring, circling birds, pouring down out of the sky in rapid succession, plunging into the water like so many projectiles and sending columns of water and spray many feet into the air like the spouting of a school of whales." Bent stated that he never heard gannets utter any sound except on their remote breeding cliffs in the Gulf of St. Lawrence, but if you are in a quiet quarter on the ferry (And if it's cold, you and a crew member out for a smoke are often the only ones on deck.) you can hear some of them protest to each other with a guttural "kuur-oak" when two birds dive past the railing like " living arrows" heading for the same target. Even though gannets have been trapped at 50-feet in New England fishing nets, and one was even reported from Salem, NJ, in a shad net; there is little need to dive deep here since their prey is a surface swimming fish, many of which are probably stunned by the swash of the propellers. From the ferry, I've never counted higher than seven-Mississippi's while waiting for a gannet to pop-up at the surface like a great white cork while struggling with its catch and its greedy neighbors. When the fishes disperse, the birds spread out too, or resume gliding behind us by criss-crossing our wake, utilizing the variable winds speeds above and aft of the boat to effortlessly coast to the next feeding ground.

A crew member once gave me an impromptu sermon about the bay when he observed me photographing gannets. In that pleasant, tight-jawed "Delmarva drawl" that identifies the real locals around the bay, he announced, "In summer, you don't see them no more." (To my surprise, he didn't know they were gannets, but seemed somewhat impressed that they are a cousin of the pelican and spend summers in the Maritimes.) He upped the ante: "See those breakwaters and the icebreakers?…(He paused; waiting for me to acknowledge the question.)… "It's a workin' bay. They shelter the ships from river ice. In 1977 the bay was locked up for a month-and-a-half from it. It comes downriver on the Delaware side." (I was tempted to bring up Coriolis Effect, but caught myself and simply nodded purposefully.) For good measure, he added, "We're a small state with big breakwaters!" (They are massive and a great spot to scan with binoculars for purple sandpipers, ruddy turnstones and other wintering and migrating birds.) I made one last ditch effort to disarm him, countering with, "I see the sports fishermen were out today. Are the flounder biting?" He raised the stakes again with, "Last week the draggers were up from Virginia. The Coast Guard chased 'em out!" "Crabs? Horseshoe crabs?" I asked lamely; but it was too late. He was finished with the conversation, and since we were nearing Lewes, break-time was over. I'd lost out again to a local with the home-court advantage.

A springtime crossing reveals an endless list of surprises for birders and as the ferry weaves between the anchored ships and breakwaters, I watch for windrows of last summer's dead marsh grasses collecting inside the arm of Cape Henlopen. These boundaries are usually loaded with birds feeding on whatever else is concentrated between the different water masses. I saw my "first" phalarope from the MV Twin Capes in Lewes Harbor and remember thinking, "Why is that sandpiper swimming?"

Lingering loons, buffleheads and Bonaparte's gulls will soon depart for their northern nesting grounds, and the dark skeins of scoters, cormorants and brant are gradually replaced by loose flocks of gray summer gulls and bright white egrets zigzagging their way north across the wide expanse of water. In spite of the cold, ospreys proclaim the start of the nest-building season by staking out all of the day-marks and lights around the waterfront, and a dock-side greeting by the season's first tree swallows confirms that it has been warm enough for the first hatch of flying insects.

Cape Henlopen sometimes gets a bad rap among birders because of unfair comparisons to Cape May and the vast numbers of birds that funnel through there in the fall, but fewer birds move north in the spring migration, simply because these represent the winter survivors. Also, the shape of Henlopen is not as prominent as Cape May and it is not as effective as a migration "trap." Still, it is not unusual to see over one hundred hawks, and many other migrants fly over the dunes on a typical spring day.

There are many reasons to be here in the spring. Often you will see your first laughing gull of the year from the ferry as early as mid-March, and you are likely to see the first tern of the year too (Usually a rugged little Forster's returning in its breeding plumage.). The blooming times of plants are earlier on the south side of the bay too and even from the ferry, you can detect flowering plants in Henlopen's dunes and stunted forests; the white of the shadbush, red of the maple and green of the sassafras. These are sure signs of spring!

Summer: Bunkers and bicycles
This brings us to summer, and what I call my "bunker to bunker bike" tour. A strategy for my friends from Wilmington, hoping to avoid the endless line of traffic to-and-from the Delaware beaches in the summer, is to detour around the bay via the ferry. I do the same by bicycle, and the flat terrain, absence of a waiting line for bikes, and bargain fare make this the preferred way to cross in the summer.

The bay's richness is evident in the summer and nothing makes that more obvious than the planktivores -- giant lion's-mane jellyfish and schools of silver-sided menhaden ("Bunker") flashing below the surface. I have never seen larger specimens of either creature than those that can be spotted from the ferry in August. The other obvious clue to productivity is the great number of fishing boats, especially in the lee of Cape May and the breakwaters; plying the waters for the queen of the bay, the weakfish (If you are from Fortesque on the New Jersey side) or trout, if you are from Lewes. The alert naturalist may also catch a glimpse of a family of dolphins, sting rays, a sea turtle basking at the surface, or even the dorsal fin of a shark, although some of these and other questionable sightings are more likely the numerous shells of dead horseshoe crabs bobbing at the surface.

If you drag a seine net along the shore, even in the worst of spawning years, you will catch fingerling weakfish and small blue crabs. If you are barefoot, you may scrape your feet on the abundant oyster and hard clam shells, two other important resources of the bay. And if you are collecting fish for the aquarium, you will be amazed and delighted at the great numbers of juvenile "tropicals" that drift north on the Gulf Stream in the summer: jacks, pompano, and even butterfly fishes.

Birdwatchers enjoy the great variety of sightings on the bay in the summer and are always on the lookout for southern strays and interesting bird behaviors. In the "good old days", before the new ferry boats were put in service (And you weren't disobeying the law by throwing snacks off the stern to attract gulls), barn swallows used to find nesting sites on the flat-topped lights over the doorways. I noticed that even though they did not seem to follow the boat across the bay, a parent always seemed to be hovering to feed the youngsters upon docking, regardless of whether we landed at Cape May or Lewes. Looking back, I wish I had found the time to study that question. Did one parent wait at each side of the bay? Did unrelated parents inadvertently feed any youngsters that arrived on any ferry, regardless of its home port? An interesting case of Capistrano coming back to the swallows, every three hours. Today, the new boats are quite a bit more upscale, the light fixtures are unsuitable for the swallow nests, and signs warn of dire consequences if you feed the birds. But I still enjoy watching what the birds are up to, reminiscing about how things were, and occasionally spilling a bag of chips into the wind.

The low, featureless coastal plain shoreline of the bay must have driven early navigators like Henry Hudson to distraction. Fortunately, even today there are no large cities at the mouth of the bay to clutter up the horizon, and the only reference points during mid-voyage are lighthouses and some mysterious obelisks, one of which should be your first destination upon reaching the Delaware shore.

These are concrete columns, called Fire Control towers, placed on the both sides of the bay. Hurriedly built during WWII, they were expected to last only a decade, but are so sturdy, with foot-thick walls and 17-foot diameters, that they still look formidable. Remarkably, each was poured in only a week as the Army reinforced defenses at the mouth of the bay. They range in height from 40 to 90 feet and were perfect for triangulating targets and directing the fire of shore batteries at Fort Miles (The other "Bunkers") guarding the coast.

They also are perfect for studying the dynamic geological forces that shape the coast, and at Cape Henlopen State Park it is possible to climb one refurbished tower to get an aerial view of not just the cape, but the whole "littoral cell" that dominates this part of the shore: from its proximal end - the sand source to the south towards Rehoboth Beach; to the distal end of the spit to the north; and across the length of the famous "Great Dune" that dominates the park.

At 90-feet above sea-level, the Great Dune is the highest spot on the beach between Cape Cod and Cape Hatteras. It is atypical because it lies perpendicular to the ocean shoreline, but this is a clue to its origins. In 1683, none other than William Penn deeded "the land of the Cape" and its timber to "forever lie in common" for the inhabitants of Lewes; one of the earliest such encumbrances on land for public use, and a good example of the "tragedy of the commons" that can be the result. The clearing of trees in the 1800's exposed sand from the bayside at Lewes and the dune has been marching inland ever since, pushed by those strong Northwest gales. Although pine trees were planted to help stabilize it, in a century and a half, the famous "Walking" Dune moved south a rate of ten feet per year.

Maps of the area dating to the 1600's, along with modern geological surveys, indicate that for the last 11,000 years, the coast has been experiencing what the geologists call a marine transgression phase. Although Cape Henlopen appears to simply be growing to the northward by the accretion of sand washed from to the south, the whole system of beaches and dunes is actually being pushed landward and upward in response to rising sea level. With more glacial melting and global warming, today's shoreline will, in thousands of years, retreat halfway across the state. In perhaps another 10,000 years, Wilmington will be "oceanfront" property, and the inundated coastal plain will be transformed back into continental shelf and bay bottom.

Originally the Cape Henlopen area was a barrier beach-lagoon system similar to what can be found farther south along the coast; and old maps show Dutch names for water bodies like Bloemaerts Kill and Hoern Kill that help reveal it. Recorded in the dunes and marsh fringe is evidence of a later recurved spit (Like Sandy Hook, NJ is today) with forested fingers of sand, dominated by pines, cherry, holly and oak, reaching into the marsh. These are the tips of ancient spits; and would have been the destination of Littoral Society New Years Day beachwalkers 500-2000 years ago. Between them are low, narrow wetlands that are probably old cat's eye ponds, which form as accreting spits reach out and encompass areas of a bay.

Maps from 1631 and 1801 show the area as a rounded cuspate spit, but since then, partly in response to siltation encouraged by those immense breakwaters built in 1829 and 1890, Cape Henlopen has been described as a "simple" spit. Although lately, affirming that the history that most often repeats itself is geological - I have noticed that a new curved finger of sand is reaching into the bay.

Today, Cape Henlopen is a great destination to do all those simple things that make an undeveloped beach so attractive: hiking, shelling, fishing and observing terns and piping plovers at their nesting refuges. It's also one of the last refuges for the ORV-crowd that gathers at the tip of Henlopen to try their luck at catching some of Delaware Bay's legendary stripers, drum, and especially weakfish.

I hate the noise and tire ruts but shrug it off, because I know the fishermen love the shore as much as I do…and that time is on the side of the birds and the beach; since the ocean will one day reclaim the coast, and the waves and currents will always wash away any marks we leave.

Cape Henlopen (From Fleming, 1978)

See gannet images and video.

Additional reading:

1. Lorraine Fleming. 1978. Delaware's Outstanding Natural Features. Delaware Nature Society, Hockessin, DE
2. The Coastal Zone of Delaware. 1972. College of Marine Studies, University of Delaware. Newark, DE
19711
3. Atlas of Delaware's Wetlands and Estuarine Resources. 1976. Technical Report #2. Delaware Coastal
Management Program.
4. Arthur Cleveland Bent. 1922. Life Histories of North American Petrels and Pelicans and Their Allies.
Smithsonian Institution Bulletin 121
5. Witmer Stone. 1965. Bird Studies at Old Cape May. Dover Publications