Over most of North America, cormorant ID used to be easy. True, there were multiple species on the Pacific Coast, a couple along the northern Atlantic Coast, and Neotropic Cormorants in part of coastal Texas and extreme southwestern Louisiana. But everywhere else, throughout the interior and the southeastern coast, it was safe to call any cormorant a Double-crested.
That’s no longer true. In recent decades the Neotropic Cormorant has greatly expanded its range. It nests commonly in the interior of Texas and Louisiana, as well as Arkansas, Oklahoma, New Mexico, and Arizona. It’s found regularly in California, Kansas, Mississippi, and Florida. Strays wander more widely every year, as far as New Jersey, Ontario, Minnesota, and Idaho. Apparently, Neotropic Cormorants could show up anywhere, and birders everywhere have reason to watch for them.
Of the six cormorant species in North America, Double-crested and Neotropic are by far the most similar to each other, so comparisons in this column will focus on these two. Neotropic averages at least 20 percent smaller, but the difference isn’t noticeable on lone birds, and it may take a second look even when they’re together. Size differences are less obvious in the south, where the resident populations of Double-crested average smaller than northern birds. With a close look, details of face pattern hold the best clues. The lores (the area just in front of the eye) are dull blackish to gray on Neotropic, almost always orange on Double-crested. This is usually diagnostic, and only a few individuals look confusingly intermediate. The bare skin of the throat is bright orange on Double-crested and has a more or less rounded rear edge where it meets the feathering of the face. On Neotropic this skin is duller yellow-orange and comes back to more of a point below and behind the eye.
On Neotropic Cormorants in breeding plumage, the throat patch is bordered by white feathers, making a conspicuous white V on the face. On Double-cresteds this is lacking, but their western populations show white tufts above and behind the eye.
At a distance, shape is better than face pattern for ID. The slimmer head and shorter bill of Neotropic are subtle, but the relatively longer tail is obvious with enough practice, either perched or in flight. On a flying Neotropic, the tail seems to extend almost as far behind the wings as the neck and head extend in front of the wings. On a flying Double-crested, the tail is clearly shorter.
For a final complication, as the Neotropic has expanded its range, it has interbred with Double-crested. Mixed pairs or hybrids have been noted in a few states. It may not always be possible to recognize hybrids, but it’s useful to know that they exist: It means that if a bird looks truly intermediate, it’s best to leave it as unidentified.
What to look for
Size and shape. About 20 percent smaller than Double-crested Cormorant, with slimmer head and shorter bill.
Tail Length. Relatively longer-tailed than Double-crested Cormorant. Lores. The area immediately in front of the eye is dark gray on Neotropic Cormorant, almost always bright orange on Double-crested Cormorant.
Throat patch. The bare skin on the throat is yellow-orange on Neotropic Cormorant and extends back to a point below and behind the eye.
Face colors. Neotropic Cormorant in breeding plumage has a white border on the throat patch, forming a distinct sideways V on the face.
Although tail length is a good mark for Neotropic Cormorant ID, it’s hard to judge from some angles. On this one-year-old bird, it’s better to focus on the face. The bare skin of the throat patch is dull yellow, and it comes back to a point behind the corner of the mouth, angling forward from there across the chin. Significantly, there’s no colorful bare skin on the lores (in front of the eye); Double-crested Cormorants almost always have bare orange lores. Young Neotropics also tend to look darker on the underparts than young Double-cresteds, which may bleach out to almost white. It takes practice to see more subtle things, like the smaller head and bill on this bird.
In perfect profile, this bird shows all the field marks for adult Double-crested Cormorant. The bare skin in front of the eye is conspicuously bright orange. So is the bare throat patch, the back edge of which is somewhat rounded. The tail is relatively short, only about the same as the combined length of the head and bill. The covert feathers on the wings, easily discerned because of their dark edges, are somewhat rounded; these feathers are more pointed on the adult Neotropic Cormorant. In breeding plumage, white tufts of feathers above and behind the eye are obvious in western forms of Double-crested Cormorants, but the white is limited or absent farther east.
With a good view of a flying cormorant, you may be able to see the shape of the throat patch (and its white outline) if it’s an adult Neotropic Cormorant in breeding plumage, as in this photo. If it’s a Double-crested, you may be able to see the bright orange throat and diagnostic orange in front of the eye. But if you can’t see those specific points, it’s better to look at the other end of the bird. Neotropic Cormorant is notably long-tailed. The length of the tail behind the wings appears to be almost the same as the length of the neck and head in front of the wings. After enough practice, this is visible at a long distance.
Since Double-crested is by far the most widespread and common cormorant in North America, it makes a good starting point for comparisons to all the others. Birders may get into the unfortunate habit of ignoring the common birds, but by carefully studying Double-crested Cormorants at every opportunity, you’ll be better prepared to detect a Neotropic Cormorant (or other species) when you see one. It’s especially good to have a clear mental image of the relative tail length. On a flying Double-crested, the bulky neck and head extend well out in front of the wings; the length of the tail behind the wings is always less. In this photo, the shape of the throat patch is also easy to see.
A Caribbean mystery
Until about a decade ago, one of the great mysteries in North American birding was the lack of any Florida records for Neotropic Cormorant. It seemed the species would have had ample opportunity to stray there. Not only was it a common breeder as close as Louisiana, it also had thriving populations in Cuba and the southern Bahamas.
The drought was broken in April 2007 when a Neotropic Cormorant was photographed near Key West. In the decade since, several other records have accumulated, mostly in southern and southeastern Florida. Since 2012, one or more adult Neotropics have joined a breeding colony of Double-crested Cormorants at Delray Beach — apparently interbreeding with them and adding hybrids to the mix for ID confusion.
An older mystery involves the breeding cormorants of San Salvador Island, in the southeastern Bahamas. For many decades, visiting ornithologists had noted that cormorants nested around the salt lakes on the island, but reports diverged on whether they were Double-crested or Neotropic. Finally in 1991, three scientists associated with the Smithsonian solved the riddle. Double-crested Cormorants nesting on San Salvador represented a new form, previously undescribed to science. This new subspecies, P. a. heuretus, is smaller than other Double-cresteds — about the size of a Neotropic Cormorant. We have no evidence that it wanders to Florida, but if it did, it would add to the challenge of cormorant ID there.