Seabirds, on the Move

30 July to 3 August

Isn’t it remarkable how quickly things change? After all, it’s only been a couple of weeks since our last installment, granted, we were in port for almost half that time. Nevertheless, the beaches remain crowded with holiday sun-seekers, tourist shops are doing a brisk business in souvenir bling, and summer appears to be in full swing.

But birds are already on the move, heading south to escape the inevitable snow and cold of the Northern Hemisphere winter—south to warmer climes and easy living—easy living that is if one survives the perils of fall migration. This past week we got a sneak preview of fall migration, finding many species not previously recorded on AMAPPS 2013, most of them early fall migrants. Most obvious of these were landbirds slightly off course—hatching year birds making their first trip south—a Cape May Warbler, several Barn Swallows, and single Tree Swallow, Brown-headed Cowbird, and Red-winged Blackbird. We also saw our first Long-tailed Jaegers, a couple of juveniles heading south with a small flock of Parasitic Jaegers; our first South Polar Skuas (going which way is anyone’s guess!); and our first Red Phalaropes.

Cory's Shearwater

Cory’s Shearwater. Photo credit: NOAA/NEFSC Desray Reeb

All this made for a banner week for the seabird team, recording 28 species, exceeding our previous high by 50%. Furthermore, our average daily species total was 11 (our highest ever) reaching a cruise high of 17 species on Wednesday. In keeping with this record-setting pace, we tallied our highest total number of individuals this week: 1260.

Was anyone wondering where all our Cory’s and Great Shearwaters had gone? We certainly were. It’s all about location: they were all up on the shelf, south of Nantucket and Martha’s Vineyard. Fifty-three percent of the birds seen this week were these two widespread North Atlantic shearwaters. Add in 305 Wilson’s Storm-Petrels, and these three species accounted for 77% of the birds we saw in the strip transect this week. These are the only species that had a 100% relative abundance (seen every day).

This might look like your routine run-of-the-mill seabird composition and abundance, showing little daily variation. To a certain extent it is. This week though was studded with stellar highlights, keeping the excitement level on the flying bridge at red alert. Somewhat northwest of the Gulf Stream, where one expects to see them, was not one, but two Black-capped Petrels, seen about 70 nautical miles southeast of Nantucket During the entire 2011 cruise we found a grand total of two White-faced Storm-Petrels—this week we saw six!

These numbers make many land-based observers swoon, but it just gets better. A very cooperative Barolo Shearwater flopped and splashed just meters off the starboard bow, reluctant to fly for fear of losing the juicy fish dinner it was struggling to hang on to. There are only about 10 occurrences of this small black-and-white shearwater in North America since 2000 after a 100 year absence, including four in 2012. With increased observer effort made possible on NOAA research cruises, this species may prove to be a very rare non-breeding visitor to this area in fall from its breeding sites in northern Macaronesian islands (Canaries north to the Azores).

(written by Michael Force and Nicholas Metheny)

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