Photo Quiz #28 Answer
By Jim Burns
Back in June when Shawna Lawry was slating up her Tevas after the great cormorant debate (see why the common names for specific birds should ALWAYS be capitalized!), Maricopa County birders should have been lining up to take her out for a real meal. Here in the desert we don't see many cormorants and we don't see any on a regular basis. The series of June sightings and Rich Ditch's great cormorant photos (now you see?) should have gotten our attention and enhanced our cormorant skills. Let's see if you did your homework and how you're doing?
If you have studied the geographic distribution of cormorants and if you've ever stood along the California coast or even along the river bank west of Phoenix and looked at mixed flocks of cormorants flying over, you're aware of two things: color isn't as important as structure; and comparative flight jizz may be most important of all. Like some other families of birds (pelagics and raptors come to mind), distant flying cormorants may be easier to identify than close roosting ones.
A) Good photo, easy bird
Since we don't have flight shots, this is about as diagnostic a cormorant photo as we'll ever get because it provides unobstructed profile views of several key family structural characteristics. Let's take it from the top left and work down through the five features which should become routine roosting cormorant checkpoints for you. This bird has a long bill, a rounded crown, a thick neck, a heavy body, and a short tail. If you're uncomfortable assigning these adjective to a lone bird, go ahead and compare its body parts with those visible on the remaining three birds in the quiz. The five modifiers still seem to work when used in comparison to others in the family.
We could next do a part by part process of elimination on the six, but let's just skip right away to the one obvious plumage feature in our first photo, the white throat patch. Only Great Cormorant (now you see!) and Brandt's Cormorant will show this extensive light throat feathering. Great Cormorant, a Canadian maritime breeder, has a flat crown and a yellow chin which, even in black and white, would show as a light area of contrast between white throat and gray bill.
This Brandt's Cormorant, a non-breeding adult (note the lack of neck plumes and the dark breast), was photographed in Pacific Grove, California in October, 1991. Brandt's is our largest west coast cormorant. Would Brandt's be possible along the Scottsdale Greenbelt? To my knowledge there are no Arizona records, but in summer it ranges to the north end of the Gulf of California. I saw my first Great Cormorant on a freshwater inland lake in Florida. Anything's possible!
B) Good photo, difficult bird
Alright, let's repeat the drill of for our second bird: short bill relative to Brandt's but not as flat as the birds' in the third photo; thinner neck relative to the Brandt's, though it is somewhat more extended here; skinny little body; long tail relative to Brandt's and relative to its own body length. This is not a Brandt's. Nor or a Great.
Plumage features should help us eliminate Pelagic Cormorant and Red-faced Cormorant, the two small-headed, slender-necked, thin-billed members of the family. Except in breeding plumage, and our quiz bird certainly isn't showing any ear tufts or neck plumes, Pelagic has an all dark bill, face, and breast. It is the smallest of our cormorants, pencil-necked and very thinned-billed. Red-faced has a yellow bill which might match our bird, but even in juvenile plumage it has a dark breast, whereas the breast on this bird appears somewhat mottled, lighter than the rest of its body, certainly lighter than the dark breast of the Brandt's.
So, we've come down to Double-crested or Neotropic. This is the same dilemma posed by Rich's web photographs of the Charthouse bird in Scottsdale last June and, in fact, this is the same bird, probably photographed on the same pipe head, a few days after Rich was there. Structural features provide good clues in separating Double-crested from Neotropic, but some if not all can be inconclusive without the species side by side.
Since Double-crested and Neotropic are the pair we should expect to have to separate here in the Valley we should run through this structural litany first. Double-crested is noticeably larger cormorant than Neotropic, eight to ten inches longer with a foot longer wingspan. It has a longer bill, larger head, thicker neck, heavier body, but shorter tail than Neotropic. Separating the tow species sounds easy and, in flight, it is relatively easy with a little comparative experience.
In flight Double-cresteds' head and neck extension will be twice the length of its shorter tail, whereas on flying Neotropics head and neck extension is the same length as tail extension. In a personal comment Pete Moulton observes that in-flight Neotropics alway sremind him of Anhingas because of the long tail and slender head/neck profile. Nonetheless, because Double-crested an Neotropic superficially resemble one another, identifying individual roosting birds is much more difficult. There are five plumage characteristics that may help.
The most important of these and the easiest to dicern is color of the lores. In all plumages, Double-crested Cormorant will have orange lores (the area of bare skin and small, sparse feathers between the eye and the bill), Neotropic dark lores. On juvenile birds (remember the light breast coloration tells us this is a sub-adult bird) the D-c bill will be orange, Neotropic dark. On D-c's the gular sac (the bare skin below the mouth) is rounded and shows no border on the orange, on Neotropics tapered to a point and bordered with white, a feature much more obvious in breeding plumage. And lastly, given good views, D-s's will show rounded scapular tips, Neotropics bluntly pointed.
Let's score our second bird on these five features. There certainly is no contrast between the color of the lores and the color of the crown. Score on for Neotropic. Though the gular sac itself is obviously lighter, there is no apparent contrast between bill color and crown. If this is a Double-crested, it is not a juvenile. The rear border of the gular sack looks pointed until compared with the two birds in the third photo. Then its most closely matches the left-hand bird which has a rounded gular sac compared to its companion. But, since this is a sub-adult, we're not sure how fully developed this feature may be. Score this as inconclusive. There is definitely a thin line of white feathering developing along the border of the gular sac and the two scapular feathers we can see appear more pointed than the scapulars we can see on the left-hand bird in the final photo. Score Neotropic on these two features.
C) Bad photo, easy bird
Serious photographers are typically equal parts tech geek and control freak. While I can't claim much of the former, I must admit a huge ration of the latter. Imagine my frustration when my photo lab ruined the best diagnostic photo I have ever taken. This third photo looks grainy and dark because I've tried to salvage in Photoshop an image so under-exposed I wouldn't even try to use it in a slide presentation. I asked the lave for a push and it didn't happen-human error I was told.
The big, hulking cormorant on the left with the obvious orange lores and the rounded gular sac and scapular feathers is Double-crested. Its little companion with the pointed, white bordered gular sac is a Neotropic. Both adult birds, this lucky side-by-side comparision shot was taken at Patagonia Lake State Park back in February, 1998 when Neotropics still went by "Olivaceous." any questions?
Well...yes, there are. On close inspection the D-c is this photo shows a very thin, faint line of white along the lower rear portion of the gular sac. And the Neotropic has a bit of light suffusion in from of its eye. There is no question as to the identity of these two birds, but these two points place a shadow of doubt in my mind regarding the consensus for immature Neotropic that developed on the Charthouse bird. If it hadn't been for the proportionately short bill and long tail of our plumage considerations as always!) I wouldn't have joined this consensus. See how difficult this can be. Thanks Shawna. I think.