New England Seabirds - Shearwaters

Cory's Shearwater Complex

Cory's Shearwater Calonectris diomedea borealis

Scopoli Shearwater Calonectris d.  diomedea

Cape Verde Shearwater Calonectris edwardsii

History of Scopoli Shearwater in New England

Cory's Shearwater photographed by Scott Surner . Note the clean white belly and yellow bill. What a beautiful picture. What a difference good light makes in a photograph.

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.

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. 

 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 Complex.
 

Maps of Breeding Areas in the Atlantic and Mediterranean for the Cory's Shearwater Complex
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.

Underwing of the Cory's Shearwater show the abrupt separation of the dark wing tips from the underwing coverts.  This can also be seen in the photograph above by Dave Larson. Underwing  of the Scopoli Shearwater to the right shows a " smaller dark tip due to paler bases to the primaries." (Olney 2007) (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 Trimble.

Scopoli Shearwater  by Jeremiah Trimble For some excellent photographs of Scopoli Shearwater from Italy http://www.pbase.com/dophoto/profile

Scopoli Shearwater  by Jeremiah Trimble

 

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.

Documentation of the History of Scopoli's Shearwater in New England

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 identified.

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.

2007 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. 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 on a rocking boat?