I know, I know, this is tough. But hang on, let’s go through this together.
As mentioned in the post when the birds were first introduced, they are much larger than swallows, much larger; goose, duck, heron, etc., size.
You might be tempted to say the birds are ducks, or better, geese, simply because they’re flying in “V” formation. Ducks and geese do fly in “V” formations as well as echelon (like a V with one side removed, as in / or \ ). Other birds fly in these formations too. Herons and egrets, pelicans, swans, cranes, and other water birds, waders and shorebirds may use the “V” formation to help keep themselves on a steady course. It’s possible to see any of those species or groups of birds in our area, even American white pelicans.
But first, let’s consider exactly what’s visible in the photo, a flock of birds flying in “V” formation. Their identity would have to include one of the species or groups above, but which one? Ducks and geese, the most obvious choice, can be eliminated by what is visible on each individual bird. Each bird seems to have a long outstretched neck, but there’s also a good amount of the bird projecting from the rear. Ducks and geese have long necks and but relatively short tails. There appears to be more tail than neck on the birds in the photo, or at least an equal amount of both.
Cranes can be eliminated. They fly with their very long necks outstretched before them but their relatively short tails do not project far from their bodies. Although their long legs extend beyond their tails when in flight, there is still more head and neck than there is tail and legs in the birds’ silhouette. Remember, our birds look to have both long necks and tails, although they’re slightly heavier on the tail end of it.
Herons and egrets fly with their necks folded. There would be very little showing in front of the birds. They’re not herons or egrets.
Pelicans too, fly with their necks folded. However, their heavy, long bills project well out from the body when flying which would create the illusion of a long-necked bird flying overhead. But, their short tail eliminates both pelicans, American white and brown pelicans. Besides, brown pelicans, though common along the coast are listed as very rare here in the Piedmont. Still, nine were seen in May of 2014 flying over Falls Lake. And besides the lack of a long tail, white pelicans would be obviously white with contrasting black flight feathers, even at the distance involved here.
I mentioned above that they were large birds. There are not many large, formation-flying birds left to consider when you’ve eliminated goose, duck, heron, crane, and pelican. Cormorants come to mind.
There are two species of cormorant to be seen in our area, due almost entirely to our two large, local reservoirs, Falls Lake and Jordan Lake. Those species are great cormorant and double-crested cormorant. Both are long-necked birds with equally long tails which project well beyond the body in flight.
Great cormorant is listed as “very rare migrant” and “winter visitor,” or “accidental” in our area, depending on which bird list you reference. When they are seen here, at one of the reservoirs, it’s usually only one or two birds. There’s not much information visible on the birds pictured to distinguish between the two cormorants at the distance they were photographed. But’s, it’s not likely you’d see a flock of great cormorants flying overhead here in Durham, NC.
Double-crested cormorants are in the area year round, thousands of them. They nest at Jordan Lake.
This flock of 18 double-crested cormorants flew over the museum’s wetlands on October 16, 2014, sans moon.
The waxing gibbous moon was photographed on December 13, 2013, sans cormorants.
Here’s a link to an older post about the species in our wetland (cormorant).