Big Cypress

Big Cypress National Park Service U.S. Department of the Interior Big Cypress National Preserve What’s the Big Black Bird? Ever wondered, “Is that a cormorant or anhinga? These birds are often confused for each other at first glance due to their similar appearance. Both birds are primarily black and approximately the same size. The cormorant is 33 inches long with a 52 inch wingspan; the anhinga is 34 inches long with a 48 inch wingspan. Both feed by gracefully diving below the surface for fish, but look closer and you’ll see that the two birds are very different. T hirty-seven different species of cormorants exist in the world, six occur in North America, but only the Double-crested lives in Big Cypress. Double-crested cormorants look for realty in a variety of habitats, shopping for open water from swamps to the ocean. Take a look at one here, and then try and find one back home. Just like many of us like to migrate south to escape cold winters, many of these cormorants also spend summers in the north and winters in the south. Between their different homes, and migration in between, Double-crested cormorants can be found in every state at some point during the year. Four different darter species exist worldwide and only the anhinga, pronounced an-hing-GA, makes its home in the Southeastern United States. The anhinga is a darter which is a tropical waterbird with a long thin neck and thin pointed bill. Typically anhingas live in freshwater wetlands, but can also survive in brackish and saltwater habitats. Cormorants and anhingas both make Big Cypress National Preserve home year-round. Look for these intriguing residents perched or swimming in the Preserve’s freshwater canals and learn how to distinguish one from its look-a-like. Who’s making an appearance today? In the field, when not posing side-by-side, it can be a challenge to tell them apart. With these helpful hints, can you detect which bird you are looking at? Bill Shape: Both birds have relatively thin, long bills. Focus your binoculars on the bill’s tip. The cormorant’s bill is hooked at the tip. The anhinga’s bill comes to a sharp point. If you’re still not sure: Take a look at the neck. It’s harder to see when not posing side-by-side, but the anhinga’s neck is longer and skinnier than the cormorants. Cormorant (left) Phalacrocorax auritus and anhinga (right) Anhinga anhinga. More than just a big black bird... Invader Patrol: Unfortunately, non-native fish such as walking catfish and oscars have invaded Big Cypress Swamp. The anhingas and cormorants eat many of these fish, helping reduce these invasive populations. Environmental Detectors: A healthy number of cormorants and anhingas indicates a healthy environment. In the 1960s, cormorant populations declined significantly due to DDT and other contaminants, but have recovered. Fishing Frenzy Eating small fish, cormorants and anhingas plunge below the surface for a tasty meal. However, just like you may argue with your fishing buddy which jig is best, cormorants and anhingas have very different fishing techniques. The anhinga makes use of another benefit of outstretched wings, thermoregulation. Cormorants have a layer of feathers that act as a warm blanket. Anhingas lack these insulating feathers and often stay outstretched to soak in the sun’s heat. Propelling themselves underwater with their webbed feet, cormorants grab their meal with their bill in as deep as 60 feet of water! Coming to the surface they swallow the fish head first. Watch their throat as their meal travels down the long neck with a few gulps. While Swimming Look! There’s a snake in the water! Or is it an anhinga? Anhingas are also called snakebirds because of their swimming style. When swimming, only their neck and head stay above the water and their body sinks below the surface. With a quick glance, their long, skinny neck might look like a swimming snake. Cormorants, on the other hand, float on the water’s surface like a duck. Anhingas also fish underwater, but spear their fish. They retract their neck into an “S” shape and thrust it forward like a spear. Their long, sharp bill can pierce fish. Once the fish is speared, the anhinga comes to land and works the fish off its bill by slapping it around and finally tosses the fish into the air swallowing it head first. Dinner is served. Strike a Pose! Take a stroll down a Big Cypress boardwalk and you might find a bird perching on a branch wings spread wide open. It seems as though it is posing for you to take the perfect picture. But what is it really doing? Photo Courtesy of Gustav Pellerin, NPS/VIP Male anhinga (left) and female anhinga (right) Did you know... You can easily determine the gender of anhingas. Typically you cannot tell the gender of diving and wading birds just by coloration. That’s not the case for anhingas! The male has a black neck and head; the female has a golden brown neck and head. Most aquatic birds have natural oils on their feathers. The oils help keep birds dry and warm, but also acts like a life jacket keeping birds buoyant. Diving birds, like cormorants and anhingas, produce lower oil levels to reduce buoyancy. In addition, water floods into small spaces in the anhinga’s feathers, helping them sink even easier. After a fishing trip, the bird must dry off so it perches on a branch with its wings outstretched. References The Sibley Guide to Bird Life and Behavior, David Allen Sibley, 2001 The Sibley Guide to Birds, David Allen Sibley, 2000 Florida Atlantic University website www.ces.fau.edu University of Florida website www.lakewatch.ifas.ufl.edu All unlisted images: courtesy of Jan Shirey, NPS/VIP Test your skills: which is the anhinga and which is the cormorant? EXPERIENCE YOUR AMERICA Anhinga or Cormorant_FINAL.indd on HQ shareall, interp publications: 4,000 printed 10/2010, stored at Oasis & WC