Chesapeake Bay Bridge Tunnel

In Brief: Northern Gannets, gulls, loons, and waterfowl in winter; passerines during migration; rarities year-round but especially in fall and winter.

Access: Details available at: cbbt.com/activities/birding. All groups must be accompanied by a security detail. All birding (currently limited to one island) must be arranged two weeks in advance. The cost per hour is $50.00 for the group. Each group member must supply personal information and sign paperwork accepting the facility’s rules and regulations. No bathroom facilities except near North Toll Plaza, where there is a a tourism center.

Telephone: 757-331-8940 or 757-331-8942

Email: paddison@cbbt.com

Additional Info: Virginia DGIF Birding Trail Site


Everything you need to know about birding

The Chesapeake Bay Bridge Tunnel

Photo courtesy Chesapeake Bay Bridge Tunnel.

Photo courtesy Chesapeake Bay Bridge Tunnel.

A marvel of civil engineering completed in April 1964, the Chesapeake Bay Bridge-Tunnel (CBBT) spans the mouth of the Chesapeake Bay, the largest estuary in North America. Here the bay opens into the Atlantic Ocean, and twice-daily tidal activity that washes across the entire facility ensures that water birds in pursuit of prey are a common sight for visiting birders who make the 17.6-mile crossing between Virginia Beach and Northampton County. Artificial rock islands anchor the facility’s two undersea tunnels, which pass beneath the Chesapeake Channel (to the north) and the Thimble Channel (to the south).

Currently, the northernmost of the four artificial islands is open for group field trips planned well in advance. Over 1.1 million tons of boulders were used to create these rocky islands and jetties, and this habitat provides resting areas for many bird species but also, importantly, habitat for marine creatures that provide sustenance for birds such as Purple Sandpipers (which pick prey from the rocks above the waterline) and diving birds such as cormorants and ducks, which extract fish, shellfish, and crabs from around the submerged boulders. Gulls and terns and Brown Pelicans often forage for fish around the islands and between them (in the channels), as the islands can serve to concentrate activity of fish with the passage of tidelines through the channels and against the islands.

Virginia’s bird clubs organize regular CBBT trips in winter, and some even hire party boats from Virginia Beach to bird the four islands from the water. In all cases, a small fee is required of field trip participants. When accompanying a group, one should take cues for birding strategies and etiquette from the leaders of the field trip. In most cases, leaders will give a short talk on the rules of the facility, so as to avoid safety problems and potential endangerment of future birding visits. Currently, the “Fourth Island” (North Chesapeake Island), on the northern side of the Chesapeake Channel, is accessible to birders, but hopefully in the future, the southern islands (on either side of the Thimble Channel) will re-open.

A Northern Gannet in flight over The Chesapeake Bay. Photo by Bob Schamerhorn.

A Northern Gannet in flight over The Chesapeake Bay. Photo by Bob Schamerhorn.

FALL

The autumn migration spans a long period, from July through December, depending on the species, but most migrants move in meteorological autumn, from 1 September through 30 November, when cool fronts and cold fronts are most pronounced. September is also the peak season for tropical cyclones, which can bring birds from oceanic areas into the mouth of the Bay, where they can be studied from land with spotting scopes. Autumn has produced records of 310 species, far more species than other of the other seasons—and over 98% of the 317 species thus far documented since 1964 from the four islands of the CBBT.

Field trips to the artificial islands can be somewhat dull during periods of high pressure and warm temperatures in fall, but there are often surprises even then. No matter what the weather, carefully check the edges of the islands—perimeter walls, base of ventilation buildings, and the visible rocky areas (do not venture beyond guard rails)—for exhausted passerine migrants, as nearly every migratory species known from the nearby mainland has been recorded on the islands. “Pishing” can sometimes help to lure shy migrants into view. “Habitat” is very limited for passerines, which often hide beneath parked vehicles or crouch in short grass. After looking for land birds, use binoculars to scan the bay (and the ocean to the east) quickly for bird activity, and then a spotting scope to investigate flocks or get better views of distant birds. When birds are numerous, scanning for multiple hours can be especially fruitful.

Active weather systems and tidal activity help ensure that bird activity changes over the course of the day. Early morning is always the best time to be active at the CBBT, but foraging and migrating birds can be seen throughout the day, depending on the species. If possible, plan to spend multiple hours scanning the bay with scope, to see as much as possible. Good views of water birds, particularly the rarer ones, usually require a considerable investment of time. If your interest is solely in land birds, then your stay need not be long, as the turnover tends to be mostly minor after the first few hours of the morning: these birds are chiefly nocturnal migrants, and so, at least early in the autumn, new arrivals will be few from midday onward, the exceptions being diurnal migrants such as swallows, Northern Flicker, finches, and falcons.

In autumn, each week offers hope for a different cohort and mix of migrants. Knowing the timing (the phenology) of migration for each species helps birders predict and identify birds with greater accuracy; checking eBird bar charts is a fine way to prepare for any given day’s birding at CBBT or elsewhere.

September continues the parade of Neotropical migrants that had begun (as a trickle) in late July, including especially warblers and swallows and the first flycatchers. In September, species diversity is at its highest, with tanagers, thrushes, wrens, cuckoos, vireos, orioles, buntings, swift, waxwing, catbird, thrasher, Bobolink joining the fray. Lark Sparrow is often recorded in late August through mid-September. Herons often pass by the islands, as do many species of shorebird, some stopping to rest on the islands’ rocks before moving on. By later September, the first shorter-distance migrants such as sparrows, Yellow-bellied Sapsucker, Brown Creeper, kinglets, and Blue-headed Vireo put in their first appearances, and it is not unusual to see a Red-breasted Nuthatch clinging to the walls of a ventilation building, at least during irruption years. By month’s end, Yellow-rumped Warbler begins to dominate the flights of warblers, and in October, thousands can be seen, often in active migration during the day along the CBBT. Migratory Red Bats are commonly noted in fall, clinging to the sides of buildings or flying by, and rarely a Silver-haired Bat is reported. As on the mainland, lovely flights of scores of Monarch butterflies and various dragonflies can be enjoyed at CBBT in early autumn.

Brown Pelicans, Photo: Robert W. Schamerhorn

Brown Pelicans, Photo: Robert W. Schamerhorn

Migration of raptors is often observed along the span, though accipiters (Cooper’s and Sharp-shinned Hawks) avoid the over-water crossing, as do most buteos, but Northern Harrier, Osprey, and falcons do not hesitate to fly over water. A few species of shorebird can be seen in September, but foul weather conditions seem to produce the most variety; the CBBT’s only record of Ruff is from 9 September (1972). Early September brings the first migratory wave of adult Lesser Black-backed Gulls and a nice mixture of terns, often including plenty of Sandwich Terns and a few Black Terns in the feeding flocks, but the last Least Terns normally depart around Labor Day. Watch for rarer species in the tern flocks, particularly if a tropical storm has been active very recently in the bay. Patient scanning might also turn up a “tubenose” (shearwater or storm-petrel) or two, though all are rare here, unless a storm has passed. Southward migration of Parasitic Jaeger begins in earnest in later September, and unsettled weather of many sorts appears to increase chances of seeing one of these striking birds: hours spent watching feeding tern and gull flocks are often required to spot one. Atlantic Bottlenose Dolphin herds are often seen in the warmer months.

October is decidedly the time for sparrows, and most species recorded in Virginia (excepting Black-throated and Harris’s) have been documented at the CBBT at this time, 22 species in all. Clay-colored Sparrow is recorded annually, Lincoln’s Sparrow almost annually, and LeConte’s Sparrow, with nine records, should be considered when studying Saltmarsh and Nelson’s Sparrows, both frequently observed on the islands among the more numerous Seaside Sparrows. The one certain record of Bachman’s Sparrow on the Virginia coast came 12 October 1980 at CBBT, along with 15 other sparrow species, a Henslow’s among them. The next day produced a Common Ground-Dove. October has also produced numerous records of rails, including a few of the elusive Black and Yellow Rails, and many records of late passerines plus Dickcissel, Western Kingbird, Yellow-billed Cuckoo, and other sundry unexpected species. Early October can be a very good time to find Sedge Wren at CBBT. A late tropical cyclone 9 October 2016 brought a Brown Booby to the southernmost island.

Although waterfowl migration starts in August for some species, October begins the peak of their season, with 32 species recorded. On the bay, the season’s first Black Scoters and Brant and Common Loons and a few Horned Grebes turn up by early October, increasing through the month and joined by many other species. Waterfowl flocks tend to move southward in the first few hours of daylight and often contain more than one species (sometimes up to eight!), making a spotting scope a necessity to discern the differences. Powerful cold fronts that transit the northern Great Plains have also displaced mid-continental migrants like Franklin’s Gulls, 25 of which were seen at CBBT 13 November 2015 after such a front. Paying close attention to weather (and to bird reports online!) can help birders hone strategies to look for both migrants and specific vagrants: the Franklin’s Gulls were observed only because stations to the north were reporting them that morning and Kiptopeke-based observers scrambled to the CBBT.

November was a month often neglected by birders in the twentieth century, but it turns out to be one of the most interesting months ornithologically. For reasons still not clearly known, migratory western birds such as Ash-throated Flycatcher and Cave Swallow (and many others from the West) frequently show up in the mid-Atlantic states, especially in coastal areas, at this time. They should be much farther to the west and south in November, when insect prey is almost absent at the latitude of Virginia. These unusual records continue into December in some years. For birders keen to find a western species far out of range, such as Lark Bunting or Rock Wren, the CBBT offers arguably the best chance in the state for such “vagrants,” and any time in autumn can be productive. The CBBT has recorded a fair variety of such vagrants and will probably produce further “state first” records in the future. To clinch identifications and confirm records of rarer species, photographs are critical.

Even without a rarity to add spice to the day, November provides good numbers of birds to sort through. Passerine migrants are unpredictable and often scarce, though in years of finch irruptions, Pine Siskins and American Goldfinches can be seen and rarely other species such as Common Redpoll. Blackbirds sometimes pass along the span by the many thousands, sometimes holding a Yellow-headed, and meadowlarks (check for Western), pipits, and larks often patrol patches of grass, and Snow Bunting is a distinct possibility as well. The terns have all but departed by mid-November (Forster’s and perhaps a few Royals hanging on), but gull numbers increase as the season cools, and Little Gull should be sought among the Bonaparte’s, if present. By the end of the month, if not earlier, the islands host most of their winter resident species, including all three scoters, Harlequin Duck, Common (and sometimes King) Eider, Purple Sandpiper, Great Cormorant. Razorbill is rarely detected at this season but should be considered, along with jaegers and rarer gulls (Iceland Gull, Black-legged Kittiwake). A rare record of Black Guillemot comes from 30 November 1985; the CBBT’s only Northern Saw-whet Owl record was 28 November 1995.

A special note about HURRICANES AND TROPICAL STORMS

 The CBBT is closed during and often immediately following the passage of tropical cyclones (hurricanes and tropical storms) and other intense low-pressure systems such as nor’easters. In the past, when birders have been present on the islands just after significant storms, they have found a dizzying array of birds—not merely seabirds typically found hundreds of miles away in the Gulf Stream but also exhausted land bird migrants, shorebirds, gulls, terns, pelicans, even hummingbirds, Wood Duck, and rails. Some of these waifs, such as jaegers, phalaropes, Bridled, Sooty Arctic, and Roseate Terns, Brown Booby, and Brown Noddy, have also been observed from seawatches in coastal areas (and some even in flooded farm fields), but the records of the most pelagic of these storm birds—White-tailed Tropicbird, Sabine’s Gull, South Polar Skua, Cory’s, Audubon’s, and Great Shearwaters, Black-capped, Trindade, and Bulwer’s Petrels, and Leach’s and Band-rumped Storm-Petrels—are chiefly from the CBBT. Naturally, there is great interest in obtaining access after storms; check listserves and bird club websites for news of post-storm group outings. CBBT security personnel are not equipped to manage numerous small groups and thus cannot accommodate last-minute requests for access.

Northern Gannets in flight over The Eastern Shore of Virginia.

Northern Gannets in flight over The Eastern Shore of Virginia.

WINTER

 Although diversity of bird species is much lower in the winter (1 December through 28 February) than in autumn, the numbers of birds can be quite high, with loons, gulls, sea ducks, and Northern Gannet often tallied in the thousands or even tens of thousands. Depending on bay water temperatures (and prey availability), such spectacles can be seen throughout the season, though to see large numbers of Red-throated Loons, December is decidedly best, and gannets often follow favored fish such as Menhaden southward in midwinter, returning with them in late winter or early March. Among the great numbers of birds, of course, there are often uncommon species, and the most sought after of these are the sea ducks, Harlequin Ducks and eiders. These can be found amongst the large numbers of Surf and Black Scoters (and a few White-winged Scoters) that feed on fish and shellfish around the islands; sometimes, they rest on the islands’ rocks, where they are very popular with photographers. Long-tailed Ducks often forage among small numbers of Greater and Lesser Scaup and a few Bufflehead off the rock jetty at the southern end of the Fourth Island, and a few Common Eiders are observed annually, whereas King Eider has declined since the late 1990s, and it is now no longer reported annually here. Gull numbers vary tremendously from a few hundred to many thousands, and the CBBT is one of the premier places in North America to see a variety of gulls, with at least 16 species confirmed, plus several hybrids. Patient scope study of roosting birds—which will not flush if approached slowly and smoothly—is needed to find uncommon species, which regularly include Glaucous and Iceland (including Thayer’s) Gulls in winter. Lesser Black-backed Gulls are typically present in smaller numbers, but watch the passage of large tanker and other ships through the Chesapeake Channel: in their wake, thousands of gulls often follow, looking for fish, and dozens of Lesser Black-backed, plus an Iceland Gull or two, can sometimes be discerned in the distance. (Note that many Lessers will be in juvenile and subadult plumages, which can be challenging when studied at a distance!) In winter, hours of scope study are often needed to produce an uncommon species such as Red-necked Grebe, Razorbill, or Black-legged Kittiwake.

Some species of seabird are irruptive, appearing irregularly in some winters but nearly absent in others. Watch eBird reports and the various listserve and Facebook bird groups for news of Razorbill (and even Dovekie) flights into Virginia waters; the CBBT is a good place to watch for both alcids, and a spotting scope is needed for good views, particularly to check carefully for rare species such as Thick-billed and Common Murres. Other winter rarities have included Barrow’s Goldeneye (27 February 1982), Pacific Loon, Clark’s Grebe, Western Grebe, Manx Shearwater, Sabine’s Gull (9 December 2001), Black-tailed Gull, Black-headed Gull, Mew Gull, California Gull, Atlantic Puffin (16 January 1978). In addition to the last of the Atlantic Bottlenose Dolphins in December (they withdraw southward as the waters cool), birders can expect a dozen or so Harbor Seals, which seem to favor the “Third Island” (on the southern side of the Chesapeake Channel) for loafing on the rocks. Humpback Whales (mostly young males) are often observed in the distance near large feeding flocks of birds; seeing one breach can be the highlight of a winter morning.

 SPRING

 Spring migration commences with the first warm fronts from the south, sometimes as early as February, when small groups of Tree Swallows or the first Palm Warblers make appearances at the CBBT. Waterfowl migration often picks up during warm spells in February, among them flocks of swan and geese moving northward to take advantage of ice- and snow-free fields that open up for foraging. Unlike autumn, with its legions of southbound birds (the numbers of adults augmented by young of the year), spring offers less chance for both diversity of species and numbers: most passerines simply will not cross the mouth of Chesapeake Bay to reach the Eastern Shore, and indeed most species’ spring migratory routes lie to the west of the bay. Nevertheless, weather can shift or displace migrants—especially those that migrate chiefly or solely at night—and so a sharp westerly wind that comes up during the night (and/or a disorienting fog) can produce a variety of migrants, and even vagrants, on the CBBT. Watching the timing of frontal activity is key to predicting such events, though even canny predictions can prove incorrect. Such are the vagaries of migration.

Red-necked Grebe, Photo by Robert W. Schamerhorn

Red-necked Grebe, Photo by Robert W. Schamerhorn

 March is a highly variable month at the mouth of Chesapeake Bay: snow flurries are still possible, but warm weather is increasingly the norm, particularly in the twenty-first century, as the planet’s climate changes. The mixture of winter and spring avifauna makes March a fascinating month: sea ducks are still present, and gannets often return by the thousands, as ocean and bay waters warm and fish migrate back northward, but warm-weather birds like Brown Pelicans, Osprey, Laughing Gulls (with the black heads of breeding dress), and an occasional push of blackbirds or sparrows begin to be seen among the winter hordes.

 April begins to feel like spring: herons of many sorts, shorebirds, swallows, Clapper Rails, Marsh Wrens, Seaside Sparrows, Black Skimmers, the first waves of terns, and a few more passerine species start to add to the roster of species recorded at CBBT. Winter birds have become scarce, though a few gannets, gulls, cormorants (including a few young Greats), scoters, and shorebirds (Ruddy Turnstones, Sanderlings, Purple Sandpipers) provide continuity. Peregrine Falcons often nest on the high-rise bridge at the northern end of the facility (just south of Fisherman Island), and they can be seen hunting now (and throughout the year) anywhere along CBBT. Near the end of the month, flights of Parasitic Jaegers become a possibility: watch for strong easterly winds, and get out early in the morning with a scope to watch the bay. Roseate Terns also begin to pass northward at this time, but well offshore: easterly winds are needed to find one in spring near land in Virginia. Less likely, but possible, Arctic Tern was recorded 8 May 2004, during heavy northeasterly gales, among hundreds of other terns.

May is the month when birders want to be everywhere at once. The CBBT can be rather quiet at this time of year, with the winter birds having mostly departed (many exceptions possible!) and migrants seemingly absent on the islands and offshore of them. Common and Royal Terns are often observed foraging around the islands, and if weather conditions are optimal (strong easterly winds are ideal), a few more seabirds such as Wilson’s Storm-Petrel, Sooty Shearwater, and Parasitic Jaeger will put in appearances in the channels or east of the islands. As in mid- to late April, fallouts of Clapper Rail, Marsh Wren, and Seaside Sparrow occur fairly often, especially when fog rolls into the bay before dawn. In such conditions, longer-distance Neotropical migrants can also be grounded on the islands. On 19-20 May 2001, a fallout of thousands of shorebirds, warblers, flycatchers, thrushes, swallows, tanagers, and sparrows occurred along the entire span, with highlights such as 350 Common Yellowthroats, 96 Magnolia Warblers, 200 Indigo Buntings, 300 Bobolinks, Acadian, Willow, Least, and Yellow-bellied Flycatchers, 100 Gray Catbirds, 250 Eastern Kingbirds, in addition to single Gray-cheeked Thrush, Veery, Swainson’s Thrush, Ruby-crowned Kinglet, Bay-breasted Warbler, Wilson’s Warbler, Saltmarsh Sparrow, Black Tern, Least Bittern, and Black-billed Cuckoo. Stalled frontal boundaries with foggy or drizzly conditions tend to produce such fallouts on the offshore islands of New England and adjacent Canada, and this appeared to be the reason for the Virginia event as well, though such spectacles are rare at this latitude. As autumn has its “reverse migrants” and western waifs, so spring has its “overshoots,” birds that have ventured well north of their usual range. A Gray Kingbird 18 May 1978 was one such spring bird; a Purple Gallinule 25 May 1967 was another.

 SUMMER

Few birders visit CBBT in the summer months, when hot and often hazy and humid conditions are the norm, thanks to the Bermuda-Azores High. But June, July, and August all can be birdy, particularly when an early tropical cyclone makes passage into the bay, bringing with it all manner of terns (12 species), tubenoses (8+ species), and various shorebirds. Nesting species of the CBBT islands are few: domestic Mallards bred here a few times long ago, American Oystercatchers nest annually (1-2 pairs), and Purple Martin is suspected to have nested. Migration of Neotropical migrants is underway in August, but relatively few are seen on CBBT islands until late in the month, when Bobolink is often seen perched or flying by, and a scattering of warblers, Baltimore and Orchard Orioles, Eastern Kingbirds, and other earlier migrants can be found after passage of a cool front or cold front. Yellow-crowned Night-Herons begin to migrate in August, and juveniles are often seen hunting amid the rocks of the islands; other heron species are also recorded but tend not to linger as long. During a typical summer day, the checklist might not break 20 species, but plenty of Brown Pelicans, Laughing Gulls, Royal Terns, and summering Double-crested Cormorants keep the bird numbers up. On rare occasions, birders have noted a River Otter and even a West Indian Manatee from the CBBT. Summer is also a fine time to watch for sea turtles: Loggerhead and Kemp’s Ridley have been found with increasing frequency lately. Records of notable birds in the summer months include Brown Booby (5 August 2017), Magnificent Frigatebird (3 June 1968), and Sabine’s Gull (20-22 June 1968).