Humpbacks and seabird bonanza in the Great South Channel

Earlier this week, I joined the annual CRESLI whale watching adventure to the Great South Channel, a gouge in the seabed that separates Cape Cod and the Nantucket Shoals from the western edge of George's Bank. This north-south passage is used by several species of whales in the spring and fall as they transiting between the hyper-productive waters of the Gulf of Maine and warmer but less bountiful waters of the mid-Atlantic and Gulf Stream.

Organized by Dr. Artie Kopelman, this 51-hour trip aboard the 140 foot (42.7 meter) Viking Starship departs from Montauk, NY and is designed to intercept female Humpback Whales Megaptera novaeangliae and calves of various ages as they feed intensively on herring and other small fish in anticipation of their southward migration to the tropics. This has to be one of the best opportunities to see, hear and dare I say it, smell, Humpbacks in the North Atlantic! One of Artie's most frequent calls over the PA system was, "we are officially surrounded by whales", his glee barely concealed. The unflagging enthusiasm of the CRESLI participants is equally impressive. Each and every whale encounter is greeted with the same unfettered excitement as the first - a rare thing in these jaded, 'I've seen it all', times.

For our entire stay in the GSC, it was almost impossible to look around and not see a breaching animal or puff of blow. Even at night, the insomniacs were busily whalewatching by deck light as a group of inquisitive animals loafed alongside the Viking Starship, spinning lazy somersaults a few feet from the rail throughout the early hours. This amazing show continued well after dawn, with the youngsters rearing up out of the water to get a look at the peanut gallery of 'oohing and 'ahhing' spectators leaning over the rail, pocket cameras and coffee cups in hand. Although rich in plankton, the green water was still clear enough for us to see the white underparts and enormous flippers of the gyrating animals below us and we marveled at their ability to 'turn on a dime', breaking the surface with a squeaky puff on one side of the boat and then the other.

Researchers from the Whale Center of New England were aboard, including Jennifer Tackaberry who manages the North Atlantic Humpback Whale catalog. Some 28 different individuals were photographed and Jen, who knows her catalog inside out, recognized 18 previously named individuals. At least three mother/calf pairs were studied at length to document the pairings, providing information about breeding success, reproductive rates and so on. The fact that at least 10 of the photographed whales were unfamiliar is particularly exciting, evidence perhaps of an influx from elsewhere. Further scrutiny of the images and databases may shed more light on this. We probably saw more whales than this but just did not have time to sit alongside each and get usable images of the raised tail flukes to allow unambiguous identification.

Early in the trip we encountered a good-sized Fin Whale Balaenoptera physalus, a handful of Short-beaked Common Dolphins Delphinus delphis and on the second day, a highly cooperative pod of 30 or so Pilot Whales Globicephala sp. that swam alongside for a while, allowing their curious calves to peek at the boat. Eventually, the pod grew tired of us and simply vanished into the depths. With water temperatures in the mid-50's, I would predict these to be Long-finned Pilot Whales Globicephala melas, however, the lack of a prominent pale patch behind the dorsal fin on the adult male and larger females raises the possibility of Short-finned Pilot Whale G. macrorhynchus. There seems to have been an incursion of warm water onto the Continental shelf this summer, evidenced by better than usual numbers of Cory's Shearwaters Calonectris diomedea in New England and New York, and so Short-finned might not be such an outlandish possibility.

Although the trip is focused on collecting population data on the Humpback Whales as part of on-going CRESLI and WCNE research projects, it provides great opportunity to study and photograph a variety of seabirds. The numbers of Great Shearwater Puffinus gravis, Wilson's Storm-Petrel Oceanites oceanicus and Common Tern Sterna hirundo were truly impressive. In fact, the throngs of commoner species were overwhelming at times and with only four sets of eyes scrutinizing the birds rather than fixed on the whales, lots of good stuff was probably missed in the happy chaos. Highlights were a South Polar Skua Catharacta maccormicki that passed right over the bow, good numbers of Pomarine and Parasitic Jaegers Stercorarius pomarinus and S. parasiticus and at least fifteen Leach's Storm-Petrels Oceanodroma leucorhoa. Landbird migration is getting underway and we were visited by several sandpipers, three warblers and a Purple Martin Progne subis. It would be great to have more seabird enthusiasts join us in future years to help pick through the abundant birdlife. My daily bird counts are as follows:

DAY 1 (11 Aug 2008)
Emerged from the banks of mist filling Nantucket Sound shortly after dawn and spent the entire day over the GSC, surrounded by whales.

Cory's Shearwater - 35
Great Shearwater - 5,119
Sooty Shearwater - 65
Manx Shearwater - 5
Wilson Storm-Petrel - 1,240
LEACH'S STORM-PETREL - 6
Northern Gannet - 6
Semipalmated Sandpiper - 3 (briefly inspected boat before moving on)
Red-necked Phalarope - 1
large shorebird sp. - 10+
Herring Gull - 5
Great Black-backed Gull - 45
Black-legged Kittiwake - 1
Common Tern - 1,450
SOUTH POLAR SKUA - 1
Pomarine Jaeger - 12 (incl 3 ads)
Parasitic Jaeger - 2
Northern Waterthrush - 1 (Nicknamed "Lucky" the bird flew around the ship many times before gaining the courage to land. Fed and watered by some kind-hearted participants, and narrowly missing being stood on several times. Remained for most of next day until jumping ship when Nantucket and mainland in sight).
Prairie Warbler - 1 (spent a few hours inside the main cabin before disappearing)

DAY 2 (12 Aug 2008)

With whales from pre-dawn to 10 am when we began the 12.5 h steam back to Martha's Vineyard (4:00 pm) and Montauk (10:30 pm).

Common Loon - 9 (Nantucket Sound)
Cory's Shearwater - 39
Great Shearwater - 2,159
Sooty Shearwater - 19
Manx Shearwater - 1
Wilson Storm-Petrel - 357
LEACH'S STORM-PETREL - 9 (several close to vessel)
Northern Gannet - 5
Herring Gull - 18
Great Black-backed Gull - 67
Laughing Gull - 30 (Nantucket Sound and Martha's Vineyard Sound)
Black-legged Kittiwake - 1 (harassed by Parasitic Jaeger)
Common Tern - 980
Black Tern - 1
Pomarine Jaeger - 3 (including 1 adult with large tail spoons)
Parasitic Jaeger - 4
Northern Waterthrush - 1 (from previous day)
American Redstart - 1
Purple Martin - 1

My thanks to Dr. Artie Kopelman and his intrepid band of CRESLI volunteers for putting together another fantastic trip.