Pleistocene Anhingas

I saw an anhinga (Anhinga anhinga) on my trip to Florida last week.  It was on the edge of a pond on the golf course behind my sister’s house.  I always see more wildlife there than I do in Florida’s much vaunted preserves and parks.  Anhingas belong to the Anhingidae family which includes just 1 genus and 4 species, but they have a wide distribution in the tropical to warm temperate regions of North America, South America, Africa, India, and Australia.  The Anhingidae family diverged from the cormorant family (Phalacrocoridae) early during the Miocene about 25 million years ago, and there is fossil evidence of anhingas in Florida during the late Miocene.  This early Florida anhinga goes by the scientific name of Anhinga grandis.  Anhingas probably originated in South America and later spread throughout the world.  There were 2 species of anhinga that co-existed in Florida during the Pleistocene–the extant A. anhinga and the extinct A. beckeri.  Anhinga remains have been recovered from 15 sites in Florida but A. beckeri fossils are known from just 4 sites.  Little is known about this extinct species, but it probably became extinct following the end of the last Ice Age when rising sea levels inundated important rookeries.  Anhingas often nest in colonies with herons and egrets, and the extinct species likely just never moved its breeding range to higher land as other species did.

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Anhinga range map.

Video of an anhinga swimming.

Anhingas are often seen drying their wings after swimming in the water while hunting for fish.  

Anhingas are also known as darters or snakebirds.  Note the snake-like head.

Anhingas hunt fish, amphibians, reptiles, and large invertebrates.  They swim underwater and impale their prey with their long bills.  When they return to shore they toss their prey up in the air and swallow it whole.  Crocodilians prey upon anhingas, but the birds are a dangerous adversary.  They aggressively fight predators with their bills, aiming for the eye.  A scout who guided the first academic ornithological expedition to the Okefenokee Swamp was blind in 1 eye because his pet anhinga had gouged it.  The anhinga is another amazing adaptable animal that has survived for millions of years.



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