Anybody out there still remember when Neotropic Cormorants were called Olivaceous Cormorants and were noteworthy items on Arizona bird hotlines, sending state listers scrambling for their binoculars and directions to chase them?  We moved back to Arizona for good in 1984, fifteen years after I began writing down when and where I saw individual species, but only a couple years after we began actively looking for new ones to add to that list.  At that time you could count the number of accepted sightings of “Olivaceous Cormorant” for the state on one hand.

Our first state record was the Kino Springs bird in February of ’91, but we had chased to no avail the one at Picacho Reservoir the previous summer.  An article in a 1993 Birding questioned the Kino Springs bird and made a case for it being just another Double-crested Cormorant.  It wasn’t until 1998 that “Olivaceous” became “Neotropic” in a decision by the AOU, and the species was first recorded nesting in Arizona in 2003.  And now . . .thousands are recorded every year on the Greater Phoenix Waterbird Survey.  But still . . . I have trouble separating Neotropic from D-c, especially immatures and even some adults in non-breeding season.

Here’s my only excuse--both species are now so ubiquitous in the Valley I’ve stopped listing them and, sadly, stopped looking at them carefully enough to differentiate them.  This, then, is a tutorial written mostly for my own benefit, but perhaps it will be of help to other birders.  Here’s a shorthand version of the seven most salient diagnostic checkpoints, in decreasing order of reliability, visuals to follow with photographs:

1—Gular pouch (the bare skin at the base of the lower mandible where the bill attaches to the neck) color, shape, and size:  Neo gular pouch is pale yellow, shaped like a “V” pointing backwards, and small, only half the size of the rest of the head; D-c gular pouch is bright yellow to orange, square or rounded at the rear, and large, the size of the rest of the head.

2—Gular pouch outline:  Neo pouch is bordered by crisp, thin white line delineating shape of pouch; D-c pouch has no border, but beware that immature D-cs may show some indistinct white feathering in the pouch border area.

3—Supraloral area (bare skin above the lores, between the eyes and the bill): Neo supraloral is same color as bill itself, mottled brown to dirty yellow; D-c supraloral is brighter, often matching the orange of the gular pouch.

4—Flight profile:  Neo head/neck extension in front of body equal to tail extension behind, giving the bird an evenly balanced flight profile; D-c head/neck extension twice that of tail behind, giving the bird an unbalanced, front-loaded profile.

5—Scapulars (individual “shoulder” feathers):  Neo scapulars are pointed, D-c more rounded.

6—Overall size:  Neo is 6 inches shorter than D-c.

7—Tail and bill size: Neo tail is longer, bill shorter than those of D-c.

There are several verities in that list.  For numbers 1, 2, 3,and 5 you’ll need to be relatively close to perched or swimming birds to focus on the diagnostic features.  For number 4, consider that you’ll see far more cormorants in flight, often mixed skeins containing both species, than you’ll see close individuals.  The good news here is that gives you a lot more practice on the most difficult to distinguish identification keys.  The bad news, of course, is that flybys can happen unexpectedly, pass quicker, and offer less time to really sort out diagnostics.  And, of course, the last three characteristics in this list may prove nearly worthless unless birds of both species are side by side.

Here are a couple close-ups which compare gular pouches and supralorals.

These next two images show immature birds and how each might be mistaken for the other species.

Images #6 and #7 are birds of the two species in flight ascending at similar angles.  The difference in overall size is not apparent here, but the photos do indicate the differences in head-to-tail proportions and “giss” (general impression, size and shape) of the species.

The following two images give a view of the difference in the scapular (shoulder) feathers, pointed in Neotropic, more rounded in Double-crested.

And, finally, a flyby shot with both species for comparison of head/tail extensions and relative overall size.

Now here’s your quiz for the day.  Based on the identification features in the column, can you put a correct label on the five birds in this group flight shot?

No?  Don’t feel too bad because the photo illustrates how important it is, in identifying flyby cormorants, to key primarily on flight profile and secondarily on the amount of color in the supraloral area.  I have all five of these birds labeled “Neotropic” in my image file.  The birds do not look “front-heavy” to me, and I am seeing no color at all in front of the eye on any of the birds.  Only on the top bird do you get a sense of the white outlined, v-shaped gular area.

You’ll know your cormorant identification skills have evolved when you are sure you’ve seen both Neotropic and Double-crested in the same flyby skein.  Enjoy.