An incredibly beautiful bird, this male Anhinga sat patiently on the nest incubating eggs. Males have mostly black body plumage. During the breeding season they develop a shaggy crest and mane, which are not apparent in this photo, but you can see the "filoplumes" on the sides of the face and neck. These feathers are silky and almost hairlike.Anhingas are aquatic birds that do their hunting under the water. With their necks coiled back, they hold their bills open a little, so when they do strike with those sharp and pointed bills, they leave two puncture marks. After Anhingas eat, they climb up on a branch and open their water-logged wings to dry.Look at those feet! I would never have guessed that Anhingas could climb trees, but they can. Their webbed feet are equipped with powerful claws that let them climb from the ground up to their nests. Anhingas build their nests over water, but not high in a tree. They like to keep them low enough so they can climb up into them. This nest was located about 15 feet off the ground. We don't have Anhingas here in Cincinnati. They are a strictly a southeastern bird, so I don't get to spend a lot of time watching them and had never seen one climb up a tree. Within two weeks of hatching, baby Anhingas can fall out of the nest into the water below them. To get back to their nest, they climb up the trunk using their claws (source: Baughman, pg. 65).
The ability of an Anhinga to strike out with lighting speed to impale its prey on its sharp bill while underwater is because of a hinge-like mechanism between the eight and ninth cervical vertebrae, and a keel on the underside between the fifth and seventh cervical vertebrae that muscles attach to. When this hinge-like mechanism is sprung, the muscles propel the bill forward like a spear being thrown (similar to herons and egrets). I wanted to see what this looked like and found a very cool drawing of a skeleton of an Anhinga's neck showing the muscles and hinge from 1913--click here for the drawing (sources: "National Geographic Reference Atlas to the Birds of North America," Mel Baughman, pg. 64--one of my favorite reference books, and a Wikipedia article on Darters, here.)
Note: The drawing of the Anhinga's spine is from "Die Vogel: Handbuch der Systematischen Ornithologie, Volume 1," by Anton Reichenow. Click here for a link to the book. If you speak German and like old pen and ink drawings, you'll like looking through the book.
A female Anhinga perches on a limb. Females and juveniles have buff-colored heads, necks and chests.
Feathers that absorb water lose their insulating properties, which causes Anhingas and Cormorants to lose body heat, so when we see them hanging their feathers out to dry, they are also using the sun's heat to stabilize their body temperature. Most of us already knew this, but what I didn't know was Anhingas have a very low metabolic rate and become chilled easily. They are dependent on the sun's heat to ward of hypothermia. As a result, they can spend up to a third of their daylight hours sunning (much more than a cormorant). It also explains why we often see Double-crested Cormorants in Ohio, but almost never see Anhingas (I've never seen an Anhinga in Ohio). An Anhinga's normal territory is the subtropical southeast (source: Baughman, pg. 65).
Because an Anhinga's tail feathers resemble a turkey's with a striped pattern and a pale tip, they've been given the nickname of Water Turkey (very fitting for this time of year...).
Anhingas, like Cormorants, do not apply waterproofing oils to their feathers to make them waterproof. Instead, the unprotected feathers absorb water, which allows them to stay submerged and swim easily under water.
Since the Anhinga's feathers are not waterproof, when they get wet, they look shiny and very smooth. When you couple that with a submerged body, a long skinny neck, and a slim head, instead of looking like a bird in the water, it looks like a black snake swimming along, which leads to its second nickname, Snakebird!
I took these photos on June 8, 2011 at the Ibis Pond rookery on Pinckney Island NWR in Hilton Head, SC, except for the last photo, which I took on March 22, 2011 at the Ding Darling NWR.
Video of a male Anhinga sitting on a nest showing gular fluttering in the heat.