Black Swan

Today on the Plumes of Oz we're going to look at the Australian black swan in the wild. Waterfowl include ducks, swans and geese and these together form the family Anatidae. The order from which Anatidae come from are the Anceriformes which really means duck-like in the Greek. So these swans have a flat bill and webbed feet. They are distinguished from ducks and geese because of the shape of the bill and the long neck. The neck of a black swan has three times as many cervical vertebrae as we have in our own neck, 23. The neck can flex but cannot extend beyond the vertical. There is also some rotation ability but no lateral movement. Swans as waterfowl live on the lakes. Their webbed feet are powerful and with a long neck they can graze off the waterweed at the bottom of the pond, feeding on the water plants and complex algal forms called stoneworts. The black swan is an Australian icon, being an emblem representative of Western Australia where it was first identified by Dutch sailors in the early 1600s. Then the classic story of Willem de Vlemming, another Dutch sailor who was also probably familiar with the West Australian coast. He was searching for lost sailors and he went firstly to Rottnest and then up the Swan River in Western Australia and there sighted large numbers of the beautiful black swans. So the river was named after this sighting in 1697, eight decades before Captain Cook sighted the east coast of Australia. Today we have expressions like when pigs fly, in other words an adonation or something that represents the impossible. And so in Roman times the black swan was an impossibility. People knew well about the white swans and the mute swan had a little bit of black around the eye, so the phrase a black swan represented a most unlikely event. See the beautiful webbed feet on this black swan as it's feeding and grazing. Most waterfowl have webbed feet just like this pink-eared duck and here another Australasian black duck. Look at the webbed feet as it waddles along. Ducks and swans are both Anatidae as mentioned, belonging to the order Ancyroforms but there is one Ancyroform that is not a member of the Anatidae in Australia and this is the magpie goose. See these magpie geese perching on a stick, they don't have complete webbing of the toes and so they don't belong to the Ancyroforms and having such peculiar feet they are in their own family Ancyranitidae. Now the black swan is really a pied swan for it has white on the wingtips and this has given rise to a lot of stories in the Australian Dreamtime. Dreamtime stories in Australia and folklore from the Northern Hemisphere about the swan share similarities, revolving about the character of swans, in particular beauty, love and elegance. Tchaikovsky's Swan Lake Ballet is all about love. The Australian Indigenous Dreamtime story has similar parallels to Hans Christian Andersen about the development of this beautiful bird. Hans Christian Andersen, the ugly duckling, turns into the beautiful white swan. The Indigenous Dreamtime story of Australia is about a white swan that is pecked, it has feathers taken by other waterfowl but then the feathers are given back to it by the black crow and it metamorphoses back into a beautiful black swan with a red blood-stained bill. And so the metamorphosis to the Indigenous people of Australia from this white ball of fluff into this beautiful black graceful bird shows the respect that cultures throughout the world have had for the stunning beauty of a swan. And so the same stories develop around a black bird not seen in the Northern Hemisphere and a white bird not seen in the Southern Hemisphere. Well I should correct that, the Indigenous people did know about the white cygnet and there have been sightings of an amelanotic or leucistic black swan. The lifelong bonding of the pair of swans is exemplified in love poems and perhaps the most important one of all is Tchaikovsky's Swan Lake Ballet here performed by a pair of black swans. They aren't exactly ballerinas but this is what a pair do in their routine rituals. The male is larger and has the longer neck. A grey swan with a red bill, dark eye but the feathers are grey. Is it something different? And the answer is yes. It differs in age for it is an immature black swan. The nest of a swan is built out of debris either in shallow water or adjacent to fresh water. Swans are indeed water dependent birds feeding on the waterweed and algae from the lake. Sometimes they will go onto the adjacent grass around the lake looking for young grass shoots. Another nest situated just at the edge of water. Building the nest is done by both male and female and here you can see the bird at the nest just pulling in further organic matter to build the nest up. They like to mount it up in case of flooding. The pet takes turns sitting on the nest but it is mostly the female and after five weeks the cygnets come out of the shell. They are white and a baby swan is precocial. In other words it will have to fend for itself. The role of the adults is to keep away predators. Swans being wetland birds like still water for it is here that the water grass will grow and the algae multiply and you can see the head of the swan constantly dipping below the water as they feed. Now as mentioned the swan has precocial hatchlings that can independently feed and drink returning to the nest only to roost but the adults are never too far away usually standing watch and during the incubation period as the female sits so the male will stand watch at night. As the cygnets get older they will move away from the nest and the adults will also move further from the young until they are finally fledged. After fledging it may well be that the adults will go into a second breeding phase and 70 percent of swans have a second clutch and swans like duck will put their heads right under the water and their tails will point up into the sky as they feed. Cygnets always look so cute as they move their wings learning how to get ready for flight. As the cygnet gets older so it becomes grey its black build takes on the vermilion warmth. In the field picking a male and a female swan is difficult the only suggestion is that the male has a longer thicker neck and is a bulkier bird than the female also the bill is a little bit longer. Anatomically if captured one can sex the birds because the male swan has a penile type structure or perhaps more correctly a structure that binds the cloaca together for most mating happens in water so cloacal proximity is most necessary. Swans can be found on both fresh and saltwater lakes as long as the water is still and weed and algae are present. The binomial name for the black swan is cygnus atratus cygnus being latin for swan and atratus meaning covered in black. Here a family very close to fledging the young swans follow the female the adult male is still at the nest waiting for them to return you can see this is a good clutch of six birds and in the distance there is the adult male. Here a fledged bird totally independent of parents flying and moving about feeding itself yet it still has a little bit of residual brown and the bill doesn't have the vibrancy yet of an adult but the white tip has developed initially when a cygnet the bird had a black bill but now it's replaced with red with a white tip. Then a little later on the birds will become more of a charcoal gray going a little bit darker like this. As mentioned the food of a swan is mostly vegetarian eating weed and algae occasionally it will eat grass from the surrounding areas of the pond. The question is how does this bird achieve a nutritional status from eating a celluloid material. Here these swans are feeding on decaying lily pads you can see them swallowing the leaves. Now there may be some non-foliar food like chironomids or blood worms and these will be trapped in the bill by the laminated structure of bill and the rather prickly tongue but for all purposes these birds are eating a celluloid material. Swans spend more time feeding than most birds and it's thought because of the low nutritional value achieved from eating grassy material in the absence of a rumen that swans derive their energy from carbohydrate by eating enormous amounts for their gut doesn't produce enzymes that will break down cellulose. Remember that white ants break down cellulose with bacteria in their gut as do ruminants. So the question has always been perplexing how do swans and the other Anatidae derive their energy source. Well a partial explanation has come from some Chinese microbiologists who looked at geese and the microbiota of their gut they found that the organism in the gut did indeed break down the cellulose or the glycans into absorbable nutrient material initially as the disaccharides halobios and then following this the traditional metabolic pathways of carbohydrate metabolism all of which involve phosphorylation and there is an increased amount of ATPase in the gut endothelium of geese. So just like the termite geese have bacteria in the gut that help in the digestion of their preferred food that is water grass and algae In the breeding mode swans are in pairs but when the young come out and when they are not breeding they are group birds feeding roosting and flying as a group. In flight they are continuously moving their wings and are not really thermal gliders like a pelican. A major difference from the black swan to its northern counterparts white swans in particular the arctic swans is their migratory habits the black swan is constantly migrating but shorter distances only for food and water and watching swans in parks and lakes one is always delighted to see them either land or take off Finally the call of a swan in flight they will call as a flock but often when they're in pairs they will call to one another and the timbre of the call is a little bit like a bugle As the term swan song suggests it is the last song and the bugle is often used for the last post but irrespective of the origins of the term swan song the call of a pair of swans is very melodic. Finally I would like to mention how birds get on in the marsh and wetlands together the marshland birds like the gullinals for example this dusky moorhen seen here feeding on complex algae known as chlorophytes or stonewort the same food that swans feed on yet I have never seen antagonism displayed between these two families. On behalf of the Plumes of Oz thank you for watching this video this channel is all about birds in the wild if you enjoy the video please subscribe this will help us to bring you more videos after subscription you will get automatic notification of our next release by Plumes of Oz