For those of you who do not receive eBird alerts, I'm sorry this is so belated.
There has been a very unusually large concentration of shearwaters (almost entirely Cory's) passing by the tip of Gooseberry neck each morning. Yesterday, there was a very surprising AUDUBON'S SHEARWATER and 2 distant Sooty's, mixed in with 9 Greats and 636! Cory's. (Complete list and comments http://ebird.org/ebird/view/checklist/S38247290)
Today, we had a very slow start with the first shearwaters not arriving until 6am, and numbers not building until just after 7am. However, then the floodgates opened and we had a constant stream of birds moving by for another 2 hours (they were still moving when we left, but had slowed down drastically). (All this is in sharp contrast to previous mornings where birds were moving at dawn, and peak was between 6 and 7, with very little after 8am.) We ended today with 1397(!!!) Cory's, 5 Greats, and 4 Manx. (List with comments http://ebird.org/ebird/view/checklist/S38247290)
We do not know when this started, but it potentially has been happening for a while now. I was there midday on June 30th and had 21 Cory's and 1 Great (http://ebird.org/ebird/view/checklist/S37888489) so I would guess that there has been near daily movement at least since then.
No one knows where these birds are going, so if anyone has the time to look anywhere along Buzzards Bay, I would love to know the outcome (positive or negative).
For those interested in following this, I would recommend checking in on the 'recent visits' tab of the Gooseberry Neck hotspot for lists http://ebird.org/ebird/hotspot/L455897/activity?yr=all&m= Each day has yielded higher numbers of Cory's, so maybe this is just the beginning.