Naturalist Notebook – May 18 to May 24
On May 18
, the southwest corner of Stellwagen Bank was the place to be. If you have been following along, I am sure you are aware that Stellwagen Bank is a submerged plateau that can be exceedingly productive because of the steep incline of its sides. On this particular spring day, the southern edge was very productive. Several dozen humpback whales were seen exhibiting a variety of feeding behaviors. And not just on their own. Feeding group sizes ranged from single animals to groups of eight adult animals emerging from the same bubble clouds. One of these larger groups included a female named Palette, that would come to the surface and slap the surface of the water with her flukes as the bubbles blown by the other whales rose around the schooling fish. Both the “kicking” and the bubbles are designed to corral the schooling fish into tighter balls so the whales get more fish in each mouthful. Also included in that feeding group were a female named Pogo and her 2013 calf, a whale named Flounder, and Salt. For a complete list of the individuals identifited there today, please refer to the sightings blog.
But they were not alone feeding on the southwest corner. Woven into the tapestry of feeding humpback whales were a large pod of atlantic white-sided dolphins (referred to commonly here as Lags), numerous gray seals, and huge balls of birds. All of these animals, the small and the large, were feeding today on the same small fish, Sand Launce (commonly called sand eels). There must have been millions of them there to have attracted so many predators and kept them feeding for so much of the day.
Early afternoon also found a species a bit less common in Provincetown harbor. 2 Risso’s Dolphins (called Grampus) were seen swimming around the outer harbor. These animals are a bit larger than the white-sided dolphins more common here or the bottlenose dolphins that are more widely known. As much as 12 feet in length and of undetermined weight, they would look large beside our white-sides. Known to breach and lobtail during periods of rest, they might remain below the surface for a half hour when feeding on cephalopods like squid. Sadly, these two were reported to look in poor condition.
appeared to be a mere continuation of the day before. Again, large numbers of humpback whales were found feeding on the southwest corner of the bank. They included a number of whales that had not been identified the day before, such as Wizard, the 1990 calf of Petrel and mother of 5, and Perseid, the 1998 calf of Palette.
also provided an opportunity to view a feeding basking shark. A very large fish, the basking shark can be as long as 40 feet, but in our waters basking sharks of 15 to 20 feet are much more common. Interesting to watch feed, a basking shark just opens its mouth up and swims forward, much like a right whale. As the shark moves forward, the water passes over its gills, that extract oxygen from the water, and the attached gill-rakers that sweep the zooplankton, like copepods, out of that water at the same time.
Still another day of feeding humpback whales on May 20.
Nearly 20 of the hungry leviathons were seen on the southwest corner of the bank. Today, they were joined by a half a dozen minke whales, the smallest of the baleen whales common to our waters. We do need to remember,when we are talking about minke whales, that small is only small relative to other whales. They are still several tons larger than elephants.
Among the mix, there were also two atlantic white-sided dolphins. Yes, just 2. Usually, when you see lags, you see 35 to 70 of them. Or you might see larger super-pods of four-hundred or a thousand, but you very rarely see just 2. It’s very hard to say why there might have been only the two of them. It might be that the pod was overly spread out that day or that others were there and went unnoticed. It is also possible that they were kind of like scouts. Atlantic White-Sided Dolphins spend their lives in very tight-knit social structures called pods, like most toothed whales, but, like other odontocetes, the group might spread out to seek out a food source large enough to feed the entire pod.
Another thing of note this day was the presence of a South Polar Skua that was chasing the Herring and Laughing Gulls around the way that they, and Jaegers, chase around the terns.
The morning started foggy on May 21.
It began to lift, allowing us a visibility of 1/4mile as we came to the southern edge of the bank. Several groups of feeding whales were found, including Strike and Palette, and the trio of Wizard, Abrasion (the 1991 calf of Liner), and Mira ( a male prone to kick with its chin before slapping the water with his flukes). As the fog lifted for the afternoon, nearly a dozen and a half humpbacks were more easily spotted feeding along the southern edge of Stellwagen
dawned cold and gray. The larger group of humpacks had shifted with the food. The ones that remained on the bank appeared to be foraging in the morning (looking for food). By afternoon, they seemed to have found a school of fish large enough to attract their attention. Bubble feeding resumed and a much larger presence of minke whales was experienced.
Hazy, gray skies and a good stiff wind from the southwest made the afternoon a bit bouncy on May 23.
The captain of the Dolphin IX kept his passengers dry and comfortable by tacking wide of Wood End, keeping the stern to the seas. A large finback whale was spotted just beyond Race Point and appeared to to travelling in a very random manner except for the one surfacing. At that moment, a huge streak of neon green appeared in the water off the bow of the boat, the extended rorual pleats of the giant. While the underside of a fin whale, like the lower jaw on its right side, is a bright white in color, it appears neon green because of the presence of an overwhelming number of phytoplankters (microscopic plants) in our waters. This finback whale, rising slowly from the depths, looked like a huge tadpole, indicating that it had lunged through a school of fish deep beneath the surface. It happened only that one time before the whale appeared to go back to looking for food, but it was a spectacular look at a very close fin whale.
The earlier trip had found two humpback whales down the backside of the cape around Coast Guard Beach in Truro, but they were no longer there when the Dolphin IX got that far.
Fog and rain met us on the morning of the 24th
. Thick fog that did begin to thin as we reached the southern edge of Stellwagen Bank. It was there that a number of gray seals and a half dozen minke whales were seen. Among them, after a bit of a search, a whale named Shuffleboard was found. Photographed first in 2008, Shuffleboard was not seen as a calf and is of unknown gender. It took a little while, as the animal just randomly bounced over the southern edge of the bank, but it did eventually find a school of baitfish to feed on. Evidence of bubble cloud feeding was seen at the surface but by the time the whale came to the surface each time it had closed its mouth and begun pushing the fish and salt water against the back edges of the baleen plates.