Possible Cape Verde Shearwater

On our trip out of Lewes, DE on October 21, 2006, we saw an odd looking Cory's-type shearwater. The bird was one of 3 shearwaters that flew in roughly together.

While it was in the sun, I initially identified it as a Greater Shearwater by shape alone. When it flew into better light and the field marks were visible, it was obviously marked like a Cory's. I called to everybody (if you know me, you'll realize this means that I was screaming at the top of my lungs) that this bird could possibly a Cape Verde Shearwater. Somehow, George Jett and his magic shutter finger managed to blast off several decent photographs. Unfortunately, none of us were able to study the other two shearwaters this bird was with, though we did see nearly a dozen Cory's Shearwaters later that day, as well as Greater Shearwaters.

The look we had was not the greatest, and nobody aboard is personally familiar with the species. We are asking for birders knowledgeable about this species to please review the following photographs and my written description, and to provide comment.

My written description can be read here below the pictures.

Links to photos of known Cape Verde Shearwaters can be found here below the pictures.

Comments have been accumulated and posted at the bottom of the page. Additional comments can be sent to Paul at . All comments will be read. Comments about my jokes or personal hygiene will be trashed.

Photo #1 - Dorsal View



Photo #2 - Ventral View



Photo #3 - Dorsal View



Photo #4 - Ventral View



Cory's Shearwater Taken on the Same Day

Written Description

Conditions of the Observation
Three shearwaters were seen coming in from a distance towards the boat. As they were crossing the bow from left to right, they were in intense sunlight. When they reached the 1:00 position to the bow of the boat, plumage details were visible.

I watched only the closest bird. The bird was viewable by shape for less than a minute, and was reasonably viewable for plumage details for probably no more than 10-15 seconds. Light was decent, but was too bright to be considered excellent. I'd estimate that the bird was never closer than 100+ yards. Seas were somewhat heavy at 3'-5', but were following at the time allowing for reasonably smooth viewing. Water temperature was about 67-68° F.

Description
Shape: When the closest bird was still in bright sunlight with no field marks visible, I called it a Greater Shearwater Puffinus gravis by shape. The bird was an obvious shearwater, with fairly pointed wingtips. The wings were held rather flat, not with the strong downward bow often seen in Cory's Shearwater Calonectris diomedea. The head appeared longish and not particularly heavy. The tail did not stand out in any way to me.

Upperparts: When the bird first came out of the sun, the dorsal surface, nape, and top of the head appeared nearly, but not quite, concolorous. To me, the overall color was darkish, though not nearly dark enough for Manx Shearwater Puffinus puffinus. The bird's upperparts did not appear to exhibit the typical tannish gray color that I'd expect for Cory's Shearwater.

Underparts: As soon as the bird banked, it was obvious that the underwings were wrong for Greater Shearwater. The underwings were entirely white with obvious dark narrow margins and mostly dark primaries. The rest of the underparts were white.

Head: The head appeared hooded, never capped, throughout the period that I could observe the plumage. I was unable to describe the bill, despite trying to get a good look at it. I feel that if it had been a diomedea or borealis Cory's Shearwater, the bill would have been obvious from the looks that I was able to get.

Comparative Photos

You can see some great photos and notes on identification of Cape Verde Shearwater at Dick Newell's web site.

You can see photos of the 2004 North Carolina bird at Brian Patteson's site.

Tom Johnson has more photos of the 2004 North Carolina bird here.

Comments

We will update this section as comments are received.

Nikolas Haass
I just had a brief and superficial look at the pictures: It indeed looks very good for an edwardsii!

Marshall Iliff
I know nothing about this bird beyond what George Jett wrote in his email and the photos he attached. I can only assume that discussion surrounded Cape Verde Shearwater (C. edwarsii). Although the photos are dark, it looks pretty darn good to me -- the very slender bill (moreso than even nominate Cory's) being the key field mark.

Brian Patteson
It looks really good to me for C. edwardsii, which could easily be more regular here than many people imagine. The bird in your photos looks very slim and long-tailed. The bill looks quite slender too, and the fact that it looks dark in all four images suggests edwardsii. If it were Cory's, it would have to be "Scopoli's", but the underwing is more like Atlantic Cory's- borealis. I just wish I had some photos from comparable angles of our 2004 edwardsii, but we had very little wind that day, so it stayed low. The fact that you intially thought it was a Greater Shearwater adds support to the case for edwardsii. We found the 2004 Hatteras bird while we were scouring the Cory's for a Greater, but we had the luxury of studying the bird at rest under calm condtions and in good light.

Tom Johnson
Paul... the thin, darkish bill, dark rump, overall color all look pretty good for CV shearwater. I know there aren't many photos on the net... I took photos of the NC bird in 2004 in case you wanted to see some more

Michael O'Brien
George, I wish the photos were a little clearer (weren't there any GOOD photographers on the boat? ;-) but the structure sure looks good for Cape Verde: thin-based wings, slim body, relatively small head and slim bill. I've never seen a Cory's that looked like that. If any other photos exist I'd love to see them.

George Armistead
Interesting-looking bird and I echo the kudos to George Jett for managing pictures. Did anyone happen to make any field notes? I'd love to hear about those, see any other pics or hear some description of what the bird looked like in the field. Was a name applied to this bird at the time or did conditions allow that?   Note from Paul: Yes, I brought up the possibility of Cape Verde almost immediately after seeing that it was not a Greater.

I have still only limited experience with C. edwardsii having only seen the one in 2004 off Hatteras, but structurally I don't see anything wrong on this bird for a Cape Verde and from what I can tell other features (incl. upperpart pattern and color) seem to align as well. I am hesitant to try and make a definitive identification based on just these photos but the bird looks just too petite to be a C.d.borealis and looks too extensively dark underneath to be a nominate Cory's. The pattern of light and dark around the head/neck also suggest C. edwardsii to me.

Tony Pym
For Cape Verde Shearwater, this does look good to me. Comparing to Cory's, the photos show the more rakish Cape Verde Shearwater with its smaller darker head and slimmer bill (which is actually also duller in colour). None of the pics (even though they're dark) show any sign of contrast between the head and mantle whereas, you know, Cory's has a pale head and back - as you record 'the dorsal surface, nape, and top of the head appeared nearly, but not quite, concolorous' - this due also to the darker primaries and upperwing coverts of edwardsii.

Bob Flood
Your bird clearly is a Calonectris shearwater by plumage alone. Pink-footed Shearwater looks superficially like a Calonectris shearwater, but the plumage of the tail and upper-tail coverts of your bird eliminates this possibility (amongst other pointers). The head pattern eliminates Streaked. The plumage of Cape Verde, Scopoli's and Cory's is very similar. An important plumage difference that distinguishes Scopoli's from Cory's and Cape Verde Shearwaters is the former's dark bordered white inner webbings to the primaries on the underwing giving the impression of white fingers, which are not present on your bird. This leaves just Cape Verde and Cory's Shearwaters. If you had been able to see bill colour, greyish in Cape Verde and yellowish in Cory's, then identification could have been secured on plumage alone.

Cape Verde is the small, slender, thin billed Calonectris shearwater, whilst Cory's is bull-headed, thick-necked, full breasted etc. Your bird clearly fits the former in every respect. Thus, analysis of plumage and structure concludes your bird indeed is a Cape Verde Shearwater.

Of course, there is much, much more that could be commented on in a full discussion of plumage and structure, and I could elaborate if needed.

All that said, as soon as I saw your photographs I immediately thought the bird to be a Cape Verde Shearwater on structure alone - the thin bill, slim wings and body etc. To be safe I double checked this by reviewing my video footage of Cape Verde Shearwater from earlier in the year. The structural profile of your bird is spot on in all respects. Again, I could elaborate on this. My opinion is that your bird is a Cape Verde Sheawater and that there is sufficient information in the photographs for a rare birds panel to accept it as such.

Angus Wilson
The first impression I got looking at the photos is of a more rakish bird than I'd expect for Cory's or Great for that matter. This is impression comes from the relative narrowness of the wings and the very long but shallow bill. The dark nail is very obvious in all four shots. Upper part coloration and patterning is harder to assess from the photos but seems completely consistent with Cape Verde Shearwater (Calonectris edwardsii).

As Paul's description states, the white underwing coverts and lack of a true axillary bar rules against Great Shearwater and for that matter, Pink-footed Shearwater. Considering the October Buller's Shearwater off New Jersey it seems sensible to discuss possibilities from the Pacific. Pink-footed also has a pale bill with dark tip but in addition to the difference in underwing pattern, the bill strikes me as too narrow. Pink-foots have solid looking bills but they are not as long (albatross-like) as Cory's. It is also worth considering light-phase Wedge-tailed Shearwater. Streaked Shearwater is very easily ruled out but Wedge-tail should be addressed carefully.

For example, see the second of two images taken by Chis Collins.  Note from Paul: Angus, myself, and several others did review this carefully, and agreed it could not be Wedge-tailed.

I think we would all agree that the proportions are all wrong for Manx Shearwater and any of the smaller shearwaters including Buller's Shearwater.

After working through the possibilities, I must agree that this looks excellent for a Cape Verde Shearwater! Congratulations to Paul and his team.

Dick Newell
You have most of the features here for edwardsii, particularly the bill, tail-shape, slender wings and under-wing pattern (unlike diomedea). I would have no reason to suspect that it is not edwardsii. I assume you have seen my notes here.

Joe Hanfman
I was on the Brian Patteson trip on 8/15/04 when the first Cape Verde Shearwater was sighted. Your bird looks very good for a Cape Verde. The narrow dark bill is a good field mark. It is interesting that you originally called it a Greater Shearwater when it was in the sun. I am sending you a photo I took of the previous Cape Verde Shearwater with a Cory's Shearwater. The Cape Verde was about 90% the size of a Cory's.

Paul O'Brien
My impression is that the bill is quite thin and dainty compared with COSH, and I see the hint of a darker cap. The bill is somewhat pale with a darker tip, but the photos don't allow elimination of pale yellow, which is suggested in at least one shot. But overall, based on structure, I'd say you had Cape Verde Shearwater. I had a feeling I shouldn't pass up this trip.