The annual Massachusetts Audubon Society’s Birders Meeting took place on March 13, at the University of Massachusetts in Boston. This year’s theme was seabirds, and the talks were very informative. I found the most intriguing talk concerned research about the sand lance, a tiny fish that is a favored food of many seabirds, fish and marine mammals. Most of the research about this fish took place in the Gerry E. Studds Stellwagen Bank National Marine Sanctuary, just north of Provincetown in the Gulf of Maine.
The sand lance, a narrow and elongate fish that is at most eight inches long, is active in the water column during the daylight, but migrates to the bottom at night, when it dives into the sandy bottom and buries itself. If the bottom is disturbed, they jump out of the sand, swim forward a few yards and then dive back into the sand. There were videos of this unusual behavior.
Humpback whales have developed several foraging tactics to capture large numbers of these fish. In the daytime the whales emit columns of bubbles that surround and trap the sand lance into a tight ball. The whales then charge through the corralled fish to scoop up large numbers of them. At night, when the fish are buried in the sand, the whales employ a different strategy: they hunt in pairs, diving to the bottom where they take large mouthfuls of sand (and fish) and end up facing each other. The fish disturbed by one whale jump out of the bottom sand and swim a short distance, but the opposing whale intercepts the fish before they can dive back into the sand. Cooperative hunting.
We do not understand the ecology and population dynamics of the sand lance. The sand lance were absent on Stellwagen Bank in 2013, as were greater shearwaters, some other seabirds and humpback whales. Sand lance were fairly abundant in 2015, as were the seabirds and marine mammals. Why were these two years so different? What factors determine the abundance of sand lance from year to year? How do populations of sand lance differ between Stellwagen Bank and Nantucket Sound? It is critical that we learn the answers to these questions before it is too late, since these fish are food for many of the animals in the ocean’s vast food web.
The sandy habitats required by these fish are also being targeted as off-shore sources of sand for beach nourishment projects. We must understand the ecology and population dynamics of sand lance to ensure that mining this sand does not adversely affect the fish and the entire ocean’s food web.
Bird Sightings
Spring migration is underway! This was expected, as we had a stretch of warm days with generally southern winds beginning on March 9. And northward migration tends to occur with such tail winds pushing the birds along. Most of the rest of this column documents birds that were seen for the first time this year.
Nancy Rogers heard robins singing in West Tisbury on March 9 and I first heard them in Vineyard Haven on March 11. Some robins were caroling their summer song from the treetops while others were hopping around on lawns. This is the behavior of our breeding robins, and contrasts to the quieter call-notes and flocking behavior of our winter resident robins.
Jean-Marc Dupon spotted an osprey as it was flying over Tom’s Neck Farm on Chappaquiddick on March 9. Then, a few days later, David Stanwood observed an osprey on a flagpole in Woods Hole on March 13; it headed out toward the Vineyard with Mr. Stanwood trailing behind it in his boat. That same day, Allen Slater observed an osprey at Wasque.
Also on the osprey front, Gus Ben David notes that on March 14 he put up the 145th nesting platform. This one was placed in a marsh on Trustees of Reservations property on Chappaquiddick. Mr. Ben David started the Osprey Project in 1970, when there were only one or two pairs of osprey nesting on the Island. This effort has been wildly successful, as about two thirds of the poles are occupied.
Mr. Ben David notes that Eversource Electric Company, Island conservation groups, and private landowners are essential collaborators that have made the program so successful. Dick Jennings’ field work documenting how many young are fledged from each nest is another essential component of this program. You can help by reporting any osprey nesting activity on utility poles to Mr. Ben David at 508-627-5634. He will work with Eversource to rectify the situation and prevent power outages and the electrocution of the osprey.
Ken Magnuson found two black vultures soaring alongside three turkey vultures at the Squibnocket Beach parking lot on March 11. The two black vultures are likely migrants as this is the first sighting of this species on the Island this year.
Several migrants returned on March 12. Most notable are the tree swallows found by Mr. Magnuson at the West Basin in Aquinnah. This seems a couple of weeks early for the swallows, but birds are generally migrating earlier than they used to, and the weather was so favorable.
Kathie Case observed brown-headed cowbirds at her feeder on March 12. The next day cowbirds were at Laurie Meyst’s feeder.
Also on March 12, Vasha Brunelle reports the first American oystercatchers at the west arm of Lagoon Pond. For several years now these have been the first oystercatchers to return; most likely that pair is older and more experienced. Such older birds tend to migrate earlier than younger birds. That same day Luanne Johnson had two oystercatchers near Big Gravel Island in Sengekontacket Pond.
Also on the migration front, Lanny McDowell observed thousands of seaducks that were feeding in the tidal currents running off the eastern shore of Chappaquiddick on March 13. This is a phenomenon we used to see more frequently. They swim and dive as they float with the current and then fly back to the north to start the loop over again. Black scoters and common eiders were most abundant while other species included the other two scoters, red-throated loons, long-tailed ducks and horned grebes. This pattern used to be there throughout the winter in the 1980s and 1990s, but now large numbers are present during migration periods only. We do not know why.
Finally, Selena Roman notes a flock of ring-necked ducks on one of the small ponds along the Mill Brook in West Tisbury.
There are lots of birds around, so please get out looking for them, and be sure to report your bird sightings to birds@mvgazette.com.
Robert Culbert leads guided birding tours and is an ecological consultant living in Vineyard Haven.
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