Yesterday morning, I was privy to yet another impressive showing of fall seabirds on Cape Cod Bay. Tragically, I was otherwise disposed at the time co-hosting a live, call-in radio show about birds, which really cut into my birdwatching time. As we went on the air, I looked out the window of my makeshift “radio studio” at Mass Audubon’s Long Pasture Wildlife Sanctuary to see some stiff-winged seabirds in high, arcing flight over the churning waters of Barnstable Habor. Naked eye, and from inside a building, I was seeing birds you would normally have to board a boat to have any hope of finding – Cory’s Shearwaters.
Cory’s are the biggest of our four shearwaters, a group of wind-surfing seabirds who navigate the trackless oceans by smell, riding the wind deflected upwards off waves to effortlessly cover hundreds of miles in search of fish and squid. The northwesterly gale had apparently pushed yesterday’s shearwaters to shore, and I watched as scores of these open ocean birds were cycling in and out of the harbor, the Sandy Neck lighthouse and cottage colony in the background. The big Cory’s were joined by a minority of Manx Shearwaters, just a handful, distinguished by their darker backs, smaller size, and much faster wingbeats.
As recently as the 90s, any sighting of a Cory’s Shearwater off the north side of the Cape was noteworthy – they have always been considered the “warm water” shearwater around here. But the rapidly warming Gulf of Maine means that Cory’s are now often the most common shearwater seen on a whale watch here, plus they linger longer, with occasional sightings in December over the last ten years. From here, where they are just post-breeding visitors, they continue down to waters off South America and then over to South Africa, before heading back north to the nesting islands in spring. In some cases, these annual movements transcribe a figure eight over the entire Atlantic from near Greenland to the southern tip of Africa.
Cory’s Shearwaters nest on islands off Portugal and northwest Africa, like the Azores and Canaries, where the hair-raisingly witchy sounds of the colonies frighten many a tourist. Another population nests in the Mediterranean, but those were just this year split into their own species, the nearly identical Scopoli’s Shearwater. This split threw all the past Cory’s Shearwater sightings of birders like me into confusion while the seabird taxonomists and field guide publishers cackled evilly from their lairs while stroking their guano-stained beards and lighting cigars with flaming hundred-dollar bills. At least that’s how I imagine it happened – I wasn’t there.
Despite the faraway breeding grounds and former status as an uncommon bird here, the namesake for this species has a lot of Cape Cod in his backstory. Charles Cory was a 19th century Boston trust fund kid turned professional ornithologist and bird collector, and one of the founders of the American Ornithologists Union. He was the first to describe this shearwater from a specimen collected off Chatham. In 1882 Cory bought Great Island in Yarmouth and operated it as a private retreat and ornithological observatory, there entertaining Grover Cleveland among other dignitaries. He also bankrolled and even played on what later became the Cape Cod Baseball League’s Hyannis team. So in a way, this globe-spanning shearwater has always been our shearwater.
This isn’t the only big flight of Cory’s in recent days, as numbers have been high for at least a week, since the last northwesterly blow. Though the family and I were in town for strictly non-birding reasons, a quick scan of Provincetown Harbor on Sunday afternoon revealed Cory’s Shearwaters all through the harbor and as far as I could see down the Truro bay shore. On Monday at least 500 were reported from First Encounter in Eastham. So scan those bay and back shores on these windy days and you might be rewarded with sightings of this impressive, Cape-Coddy seabird you never knew. But wait, was that one a Cory’s or was it a Scopoli’s Shearwater you saw? You’ll have to ask those taxonomists and field guide publishers once they finish swimming through their piles of money like Scrooge McDuck.
