Seabird Hotspots and Cool Seabirds

White-faced storm petrel

White-faced storm petrel skims the ocean’s surface. Photo credit: NOAA/NEFSC Todd Pusser

Location. Location. Location. It’s as familiar a mantra out here in the patchy pelagic environment as it is in real estate sales. The ocean’s surface appears to the casual observer as one vast homogeneous salty expanse; some even go so far as to call it a watery desert. For the upper trophic layer inhabitants who are intimately linked to this ecosystem—our feathered friends—this is about as far from the truth as one can get. Sure, there are large areas of the open ocean with very low nutrients and poor primary productivity that are practically devoid of birds—or anything for that matter. Well, almost anything; in these low density areas one can always count on a storm-petrel or two. Storm-petrels might be small, but they sure are tough.

This week our tracklines took us to several storm-petrel hotspots. Where there’s food and, presumably, when it’s relatively stable in space and time, storm-petrels and other seabirds are sure to find it. Leach’s Storm-Petrel was the most abundant seabird in the northeastern edge of our study area. On Thursday, 81% of the total birds seen in the strip transect were Leach’s Storm-Petrel. In fact, of the 846 birds we found this week, 58% were Leach’s Storm-Petrels. On Wednesday, when the mammal team was attempting to resight a group of Sowerby’s Beaked Whales at the northern edge of the Northeast Channel (just off Browns Bank), there were over 250 storm-petrels scattered about. Many were too far to identify, but those that we could were Leach’s Storm-Petrels. Leach’s is a Northern Hemisphere breeder, unlike Wilson’s Storm-Petrel, the other common summer storm-petrel in the northern Atlantic Ocean, which nests during the Austral summer on the coasts of Antarctica and sub-Antarctic islands. Some of the largest Leach’s Storm-Petrel colonies in the world are relatively close (for a storm-petrel) off the eastern edge of the Avalon Peninsula, Newfoundland, with smaller colonies off Maine, New Brunswick, and Nova Scotia.

If Leach’s Storm-Petrel isn’t your thing, then we’ve likely already lost you by now. But hang on, it gets better. This week we made some exciting discoveries, finding species that are considered uncommon to exceedingly rare in the northwest Atlantic Ocean, particularly once we entered Canadian territorial waters south of Cape Sable, Nova Scotia. The status of warm water species this far north is unclear, primarily because of a lack of coverage by seabird observers. Many of our tracklines are beyond the range of most day trips, and even specialized overnight trips arranged specifically to find these much sought-after ocean wanderers can’t make it out this far (most of these sightings were 100-200 nautical miles south of Cape Sable). During the almost three days we were in Canadian waters, we found several species of seabirds whose occurrence is considered to be rare or even accidental in Canada. Five Barolo Shearwaters exceeded our wildest expectations and further clarifies the status of this rare and enigmatic northeast Atlantic shearwater. In addition, we found two White-faced Storm-Petrels (there are only about four previous Canadian records, including two photographed last August in the same general area), eight(!) Audubon’s Shearwaters, and two Band-rumped Storm-Petrels, the latter possibly a first or second provincial record. Are these four species truly this rare at this latitude, or is it an artifact of inadequate coverage at the proper time of year?

In terms of diversity and abundance, we were well within our five week average: 19 species seen this week, with a daily average of seven species (five week average 18 and 7 respectively). This is obviously nowhere near the record-setting 28 species found last week, but this week we went for quality, not quantity. In keeping with the theme of typically warm water birds farther north, we found three Black-capped Petrels, including one only 140 nautical miles southeast of Nantucket; two more White-faced Storm-Petrels along the shelf break near where we saw the Black-capped Petrel, and a White-tailed Tropicbird only 30 nautical miles south of Canadian territorial waters. Other highlights this week include several southbound migrants: Least, Semipalmated, and White-rumped Sandpipers, and single Barn Swallow and Yellow Warbler.

(written by Michael Force and Nicholas Metheny)

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