Anhinga, a.k.a. American Darter.

Florida is a great place to observe the Anhinga, Anhinga anhinga. Yep, common name, genus, and species are all the same word, derived from a South American tribal name for this unique species. Outside the U.S. the Anhingas are known as Darters, and depending on who you read there are from 2 to 4 Darter species. Ours is sometimes referred to as the American Darter, and the others are the Australasian, Indian, and African Darters.

Remember, in 2010 the family  Anhingidae was moved into a new order, the Suliformes. The Anhingas are probably closest to the Cormorants (Phalocrocoracidae), now also in Suliformes. Other Suliformes families include the Boobies/Gannets (Sulidae), and Frigatebirds (Frigatidae).

The dagger bill is a perfect weapon for spearing fish in the side, which is how the Anhinga captures its prey. The first bird a subadult, which dropped in at the small marina near my cousin's condo. Young birds lack a red iris, and are browner.

Second shot shows more of the bird. Note the long tail, well worn, and the relative lack of black and white plumage. Older birds will shown a much darker belly and the female will show a sharp division between light breast and dark belly.

Both male and female Anhingas has striking white feathers in their secondary coverts. Here's a female Anhinga, sitting on a nest at the Venice Rookery, which occupies a small island in a pond in Venice, FL. Her soft brown neck  is folded. The Anhingas seems to have inserted a dark ridged foreign object as they built the nest.

The Anhingas are colonial nesters, and seem happy here to share the safe island refuge with other species, including Great Blue Herons, Great Egrets, Yellow-crowned Night Herons, and a single pair of Double-crested Cormorants. An Anhinga nest on the "back" side of the island had a good crowd, showing chicks of various ages. Even the large bird on the right is a youngster, as judged by the short bill. Count 'em!

The large fledgling on the right may of course belong to a neighboring clutch. I counted six birds in the grouping.

The adult male Anhinga has a black head, neck and breast. This one along the shoreline of Lake Tarpon, in Tarpon Springs. Anhinga large wings are not waterproof, so they have to spread them to dry in the same manner as the Cormorants. Anhingas soar effortlessly to high altitudes, which allows them to disperse as vagrants fairly widely in the eastern U.S, and even to inland locations. Check eBird, and you can zoom in, too.

Lastly, 2 shots of the high breeding plumage Anhingas develop bright colors in the bare skin around the eyes and on the face. Suboptimal pictures, but they some of the bright blue orbital ring and the neon on the face. The blurred female in the foreground shows some of the same bare skin colorations.

This one from Fred Howard Park, 2012: