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Cory's Shearwater Complex

Cory's Shearwater Calonectris diomedea borealis

Scopoli Shearwater Calonectris d.  diomedea

 

Cape Verde Shearwater Calonectris edwardsii

 

Cory's Shearwater photographed by Dave Larson

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 Complex.
 

Clements 2007

Breeds /Disburses

Proposed

Cory's Shearwater

     Calonectris diomedea diomedea

   

 

   

 

Calonectris diomedea borealis

 

 

Mediterranean 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 Indian Ocean.

 

 Berlengas (portugal),Madeira, Desertas, Salvages, Azores, and Canary Islands. Disburses to south Atlantic and Indian Oceans

 

Scopoli Shearwater              Calonectris diomedea

 

 

 

Cory's Shearwater    Calonectris  borealis

Cape Verde Shearwater

     Calonectris   edwardsii

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

Calonectris   edwardsii

Maps of Breeding Areas in the Atlantic and Mediterranean
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.

Identification of 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 gliding. 

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 Spangenberg.

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.

Starting from the left, there is a Cory's Shearwater, Manx Shearwater, possible Scopoli Shearwater and finally another Cory's.

 


Note much smaller size of 'Scopoli's' with finer, dull bill (not yellow) and paler, lighter gray head.This bird has not been 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 http://www.pbase.com/dophoto/profile
 

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 SHEARWATER.

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 C. edwardsii (Oustalet, 1883)
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 2007)

The Cape Verde Shearwater has not been identified in New England waters.  We are looking for it.

 

Greater | Sooty | Cory's | Manx | Audubon's | Macronesian