New England Seabirds
Shearwater Calonectris diomedea borealis
Northern Hemisphere Breeders
All forms of Cory's Shearwater including the Cape Verde
Shearwater discussed below breed in Northern hemisphere.
They are working during our pelagic birding season in the
summer. Birds seen on summer trips are probably
non-breeders. Breeders may appear in our waters in fall.
The Cory's Shearwater usually seen in New
on islands outside of the Straits of Gibraltar
including: Berlengas (portugal),Madeira,
Desertas, Salvages, Azores, and
Canary Islands. Disburses after
south Atlantic and Indian Oceans.
Separate Cory's Shearwater from Great
Before you start worrying about separating the
subspecies ( or full species ) of the Cory's Shearwater
Complex, learn to separate Cory's from the more common
Cory's is slightly larger and heavier than the
Greater Shearwater and displays a yellow bill. Flight is
slower than Great Shearwater. Wings more bowed when
Photograph by Joe Sutherland with 4
Cory's Shearwaters compared to one Great Shearwater
(third bird from left).
Note larger size, yellow bills,
light gray heads with no capped appearance of the Cory's
Shearwaters as compared to the Great Shearwater which
has a distinct black cap and dark bill.
||Take a closer look at Cory's
Shearwater in this photograph by Dave Larson
Notice the gray color of the head continues down the
neck and onto the back so that the bird does not give a
dark capped appearance.
The bill is yellow with a dark
spot and the underwings and belly are white.
In this photo some of the wing linings have molted showing black flight feathers
which would appear as underwing marking when seen at a distance.
This bird is clearly a Cory's Shearwater ( not a Scopoli )
because of the abrupt line separating the dark wing tips
from the white underwing coverts.
|How To See Cory's Shearwater
Because this bird breeds in the Northern Hemisphere it is
more likely to be seen late in the summer and into the fall. Usually seen in small numbers
(0-2) on Stellwagen Bank July - August. Larger flocks of up to
40 birds may be seen south of Cape Cod.
In the summer of 2009, relatively
large numbers of Cory's Shearwaters were seen off the coast
of New Hampshire in spring and fall. This phenomenon did not
continue and only 2-4 Cory's have been seen on recent trips.
Try trips out of Rhode Island or from Massachusetts to Hydrographer's Canyon and the continental shelf edge. Whale watch out of
Nantucket may also produce this bird. Most birds are the
Calonectris diomedea borealis subspecies
The Cory's Shearwater Complex - Taxonomy Extended
Cory's Shearwater was once considered to be three distinct
species. The three species were lumped into one species named
Cory's Shearwater with three subspecies each having a distinct
breeding range. The time of the "lumpers".
Now taxonomists are having second thoughts and
recently the subspecies Calonectris diomedea edwardsii
has been elevated to separate species endemic to the Cape Verde
Islands. At present most sources consider Cory's
Shearwater to have two subspecies. Others have already
elevated the subspecies to three full species. The following
chart outlines the evolving taxonomy of the Cory's Shearwater
Calonectris diomedea diomedea
Calonectris diomedea borealis
Islands: Balearic, Malta, Sardinia,
and islands of France, Algeria, Tunisia, Italy, Greece,
and Croatia. Disburses past the strait of Gibaltar to
the North Atlantic.where it occurs west to the coast of
North America. Moves south in winter in the Atlantic off
the coast of Nambia and South Africa and some into the
Desertas, Salvages, Azores, and
Canary Islands. Disburses to
south Atlantic and Indian Oceans
|Cape Verde Shearwater
|Cape Verde Islands endemic.
Feeds in local waters during breeding. Disbursal
not well known perhaps off the coast of Senegal.
One recorded off North Carolina. Not yet identified in
New England waters.
||Cape Verde Shearwater
Breeding Areas in the Atlantic
and Mediterranean for the Cory's
Careful study of the breeding area on the following maps
will clarify these distinctions. The first shows the Atlantic
islands off the coast of the Iberian Peninsula and
Africa. Red arrows indicate the islands of concern.
The second map of the
Mediterrean Basin shows the breeding islands of the
proposed Scopoli Shearwater. The Balearic Islands just
east of Spain include the famous resort of Mallorca.
Sardinia, Malta are also shown on the map. The
bird breeds on smaller islands (not designated)
off the coast of France, Algeria, Tunisia, Italy,
Greece, and Croatia ( formerly part of Yugoslavia).
Separating Cory's Calonectris diomedea borealis
And Scopoli Shearwaters Calonectris d.d.
Once you have identified a Cory's
Shearwater and not a Great Shearwater you can turn to making sure it
is not a Scopoli Shearwater. To do this you need a
good shot at the underwing. The Cory's Shearwater has
a larger dark tip with an abrupt line between white and
dark. The Scopoli has a smaller dark tip with fingers of
white due to the pale bases of the primary feathers.
the Cory's Shearwater show the abrupt separation of
the dark wing tips from the underwing coverts.
can also be seen in the photograph above by
Underwing of the
Scopoli Shearwater to the right shows a " smaller
dark tip due to paler bases to the primaries."
(Cory's Shearwater above photographed by Jeff Slovin on June 2010 BBC pelagic to continental shelf edge.)
Scopoli Shearwater Calonectris diomedea boroli
photographed on 7/19/2008 BBC Extreme Pelagic by
Jeremiah Trimble and labeled Bird #1.
Pictures of 4 Scopoli Shearwater by Jeremiah
Trimble from 7/19/2008
Scopoli Shearwater by Jeremiah Trimble
Scopoli Shearwater photographed by Jeremiah
Cape Verde Shearwater
Once considered a
subspecies of Cory's Shearwater,
the Cape Verde Shearwater has recently been split off
as a separate species. It is
endemic to the
Cape Verde Islands. It has
an all dark, slim bill, and
darker head and upperparts than
Cory's. The flight has been
described as rather more
typically shearwater-like than
Cory's, with stiffer and more
rapid wing beats. (Onley
Verde Shearwater has not been
identified in New England
waters. We are
looking for it.
Documentation of the History of Scopoli's Shearwater in
Scopoli Shearwaters in New England Waters
A Calonectris shearwater was tentatively identified and
later confirmed to be Calonectris diomedea diomedea
or Scopoli Shearwaters on the 2006 Extreme
Continental Shelf Edge pelagic. There were some
excellent photographs taken of this bird some of which the
author does not have permission to use on the web page.
On the July 2007 trip another bird was identified as a
possible Scopoli Shearwater. On the 2008 July trip to
Atlantis Canyon 4 birds were well photographed by Jeremiah
Trimble and his photographs are used above to help with the
field separation of Cory's and Scopoli Shearwaters.
Now that we know it is possible to
encounter both subspecies in our waters, birders
should familiarize themselves with the identification of
both subspecies and look for Scopoli types on all pelagics.
I think it is beneficial to preserve Rick Heil's detailed
notes from the trips on which the Scopoli was first
The First in 2006- Comments on the probable "Scopoli's" Shearwater (from
Rick Heil 2006 Shelf Edge Trip):
Distinctly smaller, slenderer, and slightly darker
Cory's-type shearwater with a darker, shorter, and
more slender bill repeatedly followed and readily
picked out and observed from a roosting flock of
Cory's and Greater along the shelf edge west of
Hydrographer. A number of photographs were taken of
the bird on the water and in flight. Possibilities
include Cape Verde Shearwater (C. edwardsii),
in N. Am. recorded once off Hatteras, NC (15 Aug.
2004), or 'Scopoli's Shearwater' (C.d.diomedea),
the Mediterranean race of Cory's.
Follow-up from Rick Heil (posted 8/28/06):
After reviewing some (but not yet all) of the
photographs of the Calonectris Shearwater near
Hydrographer Canyon (taken by Blair Nikula, Joe
Sutherland, and Dave Larson) on Saturday's
Pelagic, I believe the bird to be of the
Mediterranean race of Cory's Shearwater, C.
diomedea diomedea, also known as SCOPOLI'S
Interestingly Petersen and Veit mention
C.d.diomedea (Scopoli's) in the Birds of
Massachusetts as being known from specimens off
Long Island, and 'kind of' predict its potential
appearance in New England waters.
This photo of shearwaters was taken by James Smith on
July 2007 Extreme Pelagic to the continental shelf
edge.The image was taken using Canon Powershot A540
through Leica 8 x 42 binoculars.
from the left, there is a Cory's Shearwater, Manx
Shearwater, possible Scopoli Shearwater and finally
Note much smaller size of 'Scopoli's' with finer, dull bill
(not yellow) and paler, lighter gray head. This bird has
positively declared a Scolpoli. Is this not an
astounding photograph to have been taken using binoculars
on a rocking boat?
Heil's Notes from the 7/19/2008 BBC Extreme Pelagic
Cory's Shearwater (11):
borealis or presumed.
possible (4): Several Cory's types appearing
more slender billed, and with white extending onto the underside
the primaries, may well be this subspecies, C.d.diomedea,
inside the Mediterreanean, and which some consider a separate
species. We have previously documented this taxon in these
first in Aug. 2006.
For a complete report from this trip see
July 2008 Atlantis Canyon trip.