New England Seabirds
Northern Hemisphere Breeders
All forms of Cory's Shearwater including the Cape Verde
Shearwater discussed below breed in Northern hemisphere.
Thus 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.
Taxonomy - What is a Scopoli Shearwater?
Cory's Shearwater was once considered to be three distinct
species. They were lumped into one species named
Cory's Shearwater with three subspecies each having a distinct
breeding range. 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 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
Cory's Shearwater Calonectris borealis
|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.
||Cape Verde Shearwater
Breeding Areas in the Atlantic
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).
How To See
Usually seen in small numbers
(0-2) on Stellwagen Bank July - August. Larger numbers (flocks up to 40) south
of Cape Cod. 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 and in the
discussion will be referred to as the Cory's Shearwater.
The Scopoli subspecies was identified on the 2006 Continental
shelf edge trip see Rick Heil's report below and again in 2008.. This subspecies
will be referred to as Scopoli Shearwater in this discussion.
Cory's Shearwater Calonectris diomedea borealis
Slightly larger and heavier than the Greater Shearwater with a yellow bill.
Flight is slower than Greater Shearwater. Wings more bowed when
Photograph by Joe Sutherland with 4 Cory's Shearwaters
compared to one Greater Shearwater (third bird from
left). Note larger size, yellow bills, light gray heads
with no capped appearance of the Cory's Shearwaters.
||Photographed by Dave Larson with a Sony Mavica Digital and
used with his permission. ( Summer 2000 on Rhode Island Audubon Pelagic trip),
Photo remains the property of the photographer. See Dave's web page for other
examples of his photography. http://larsonweb.org
|Notice the lack of dark capped appearance, yellow bill,
white underwings, and lack of spotting on the under body.
In this photo some of the wing linings have molted showing black flight feathers
which 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. A Scopoli Shearwater
has white bases to the primaries which show thru as white
fingers on the wing tips.
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. Also on the 2008 July trip to
Atlantis Canyon 4 birds were well photographed.
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.
Separating Cory's Calonectris diomedea borealis
And Scopoli Shearwaters Calonectris d.d.
Cory's Shearwater taking off photographed by Scott
Underwing of the
Scopoli Shearwater to the right shows a " smaller
dark tip due to paler bases to the primaries."
(Olney 2007) The bird
above is clearly a Cory's Shearwater ( not a Scopoli )
because of the abrupt line separating the dark wing tips
from the white underwing coverts
Scopoli Shearwater Calonectris diomedea boroli
photographed on 7/19/2008 BBC Extreme Pelagic by
Jeremiah Trimble and labeled Bird #1.
This photo of shearwaters was taken by James Smith on
July 2007 Extreme Pelagic to the continental shelf
edge.The images were 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.
For some excellent photographs of Scopoli
Shearwater from Italy
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.
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.