- Research & Education
- Cape Cod
Dolphin Fleet Birdwatching Notes: 18 to 29 May, 2008.
John C. Conlon
We are now over a month into the 2008 whalewatching season and as many of you know the year has been great. As we work our way toward summer we look foreward to this year’s visitors: whales, whalewatchers and the birdwatchers looking for pelagic birds, seabirds, that are regularly offshore of Provincetown. As we see the early arrival of summertime shearwaters and storm petrels we are still in the season to see the last of the pelagic birds that are here through the winter half of the year.
As always the first half an hour of our trip is travelling along the Provincetown beaches from Long Point to Race Point. From there most of our time this past two weeks has been spent from the southwest corner toward the middle of Stellwagen Bank. Along the way we are seeing the few gannets that remain here in second, and third year, as well as a few in subadult plumage. Black–legged kittiwakes and the beginnings of the summer terns work along the beaches. We have already seen some early arriving Wilson’s storm petrels as well as sooty and even manx sherarwaters. Small flocks of sootys are visible toward the northern section of Stellwagen Bank.
Two seabirds in particular have offered nice looks over the past two weeks. Common loons (Gavia immer) and Iceland gulls (Larus glaucoides) have both offered appearances when least expected. Both are seen locally almost exclusively during the winter half of the year. Both are unlikely to be seen much longer into the summer. And neither are seen regularly in large numbers during offshore whalewatch trips. Loons are sometimes seen in rafts of 6 to 30 or more in Cape Cod Bay during April and into May.
Common loons are often referred to as northern, or, great northern divers by European birders. At 32 inches in length, with a 46 – inch wingspan and weighing close to 9 pounds they are a large bird that is disproportionately heavy due to having relatively dense bones. This density is why loons ride so low in the water: making them difficult to spot in choppy sea conditions. It is one reason that loons can potentially dive as deep as 200 feet. Their underwater forraging can also take them considerable horizontal distance. All of this is in pursuit of small schooling fish. These vertical and horizontal distances are achieved with powrerful foot propulsion using feet that are set quite far back along the body. The legs and feet are so far back that loons are unable to stand on their feet or take flight from land. They even require long running starts to take flight from water. We often see them running and flappping across the water’s surface as the boat approaches. Yet they never actually take to the air. Rather they relocate a bit and settle onto the water’s surface some short distance away.
Loons migrate here from the continent’s interior where they breed and nest on fresh water lakes and ponds in Canada and the northern USA. Given that they are not able take flight from land loons migrate south when those lakes and ponds freeze. This brings them to New England’s coastline. It is this autumn through winter and into spring period that we see loons locally. By the time whalewatching season starts they are losing their mottled and spotted grey-white nonbreeding plumage (excluding the juveniles) and gaining the brilliant pied plumage of breeding adults. This breeding coat would not be complete without their crimson red eyes to augment the black and white feathers. It is not uncommon to see this breeding plumage at this time of year.
Look closely along the shore as loons work along the beaches and diving for fish. Occasionally they are also seen near feeding humpback whales farther offshore. Distant views of loons are more common as the birds fly north on their spring migration. Their havey wing beats, dangling feet, and outstretched necks make common loons distinctive in flight. The smaller and more rarely seen red-throated loon droops its neck and head as it flies. Migrating loons tend fly high above the water’s surface. The best way to spot them is to remain constantly alert for singles, pairs and triplets flying more than 100 feet above the water’s surface: keep in mind that most seabird sightings in our area will be less than 100 feet above the surface. These common loons are winging their way toward mist-covered northern lakes where their long, mournful, wailing calls will attract summertime mates and we will see their return to Cape Cod by the end of this summer’s whalewatch season.
We have also had great sightings of some Iceland gulls. At 22 inches in length, a 54 inch wingspan and 1.8 pounds, Iceland gulls are sized between the more familiar (to most people) ring-billed and herring gulls. Icelands are noticably smaller than their close relative the glaucous gull which we also occasionally see here during springtime whalewatching. Iceland gulls spread offshore across much of the north Atlantic Crescent for winter. This wintertime arc extends from the western Baltic Sea to potentially as far south as eastern Florida. It includes the waters off Cape Cod. By late May most Iceland gulls have migrated north toward their breeding sites in northeastern Canada (including Ellesmere and Baffin Islands) and southern Greenland.
To spot the remaining few Iceland gulls look toward the mixed feeding flocks of gulls that work above feeding fin and humpback whales. Those whales push sand lance, a small schooling fish, toward the water’s surface while the gulls wait for the easy meal. While juvenile Iceland gulls are overall lighter in color than most of the notoriously-difficult-to-ID immature gulls they are still difficult to distinguish in the crowd. The adult Icelands are much easier to spot. But in the case of both juveniles and adults they are never numerous. Nonbreeding adults, remember we are at the very end coming out of nonbreeding season in April and early May, are almost entirely white with very pale grey coloring on the wing’s dorsal side. In the bright ambient light of the sea surface Icelands will look entirely white under most circumsances. Glimpses of these Iceland gulls are brief as they move in and out of the mixed feeding flocks of gulls. The occasional brilliant flashes of white wings are a treat worth looking toward but once you spot one stay with it. The beauty is striking but they disappear quickly!