“The anhinga in truth is the very first of all fresh-water divers ...”
So wrote the great ornithologist and painter John James Audubon, who in 1821 trekked through Louisiana’s swamps to observe “with anxiety and in silence the curious habits” of these striking birds.
Anhingas are memorable sights in the Lowcountry as well.
The large, long-necked birds are common at lagoons, where they spear fish, frogs, crayfish, small alligators and other aquatic prey with their long, pointed bills.
They’re also called “snakebirds” since they often swim with just their heads and sinuous necks projecting from the water. Still another name is “water turkey” because of their long, fan-like tails.
Male anhinghas are glossy black with silver patches on the upper body and wings. Females are black with a tan head and neck.
These prehistoric-looking birds are sometimes confused with double-crested cormorants, which are close relatives. But cormorants are black overall, with less flamboyant tails and shorter, hooked bills.
Also, cormorants are found in both freshwater and saltwater habitats, but anhingas prefer lakes, ponds and sheltered freshwater swamps.
Although they’re basically tropical/subtropical birds, anhingas are native to the U.S., and in the Lowcountry, we see them year-round.
In the spring, look for them nesting in mixed colonies along with herons and ibises. The nest is a platform of sticks lined with leaves. Both parents feed the young.
The easiest way to spot an anhinga, though, is when it assumes its distinctive spread-wing posture, standing motionless for many minutes with its long wings outstretched.
Biologists once thought that anhingas lacked sufficient oil on their wing feathers, so the birds needed to spread their wings to dry them off from time to time.
We now know that the microscopic structure of bird feathers, not just oil production, also contributes to waterproofing. Anhinga feathers are adapted more for buoyancy, thereby increasing swimming efficiency and underwater fishing skills.
And the spread-wing posture so often assumed in this species may function more to regulate body temperature. Compared to many other birds, anhingas have a relatively low metabolic rate and can lose heat quickly, especially when wet.
So anhingas have something in common with human sunbathers. Exposing their backs to the sun while stretching out their wings helps them get warm.
Vicky McMillan, a retired biologist formerly at Colgate University,lives on Hilton Head Island. She can be reached at firstname.lastname@example.org.