Readers’ wildlife photos

Reader Rodney Graetz from Oz sends us photos of a unique Australian bird. His notes are indented, and you can enlarge the photos by clicking on them.

The Black Swan: An Iconic Australian Bird

The Australian swan (Cygnus atratus) is a common, unmistakable, black swan, with a white-tipped red beak.  It inhabits lakes, rivers, and estuaries, including the temporary wetlands of the arid inland.  While five hundred years ago, European explorers were astonished to find them, Australians know no other swan.

Adult swans are large birds weighing 4-9 kgs (6-20 lb) with a wingspan of 2 metres  To become airborne, a long, flapping take-off run is required.  In flight they are spectacular, displaying the hidden white wing feathers.  They are impressive travellers taking long nomadic group journeys, usually on moonlit nights, presumably to maximise the glint of water.  Their call, especially when flying, is a far-carrying, bugling. Luckily, I have heard and seen such a flight of swans on a moonlit (Easter) night.  The picture below is not my photo: never have I managed to be in the right place at the right time to capture such a perfect bird-in-flight image.

Swans are opportunistic breeders, their reproduction determined by the amount of water and food available—but it usually begins in Winter (June onwards).  Nests are usually made on floating reed masses, or on small islands.  Cygnets can swim within days of hatching, are greyish white in colour, and are always closely supervised by one or both parent birds.

As the cygnets grow, they become paler in colour.  Note their close attention to the left-hand swan, the male (longest neck) parent, even though both parents actively guide and feed them.

An advanced-age family group grazing a recreational lawn.  The male bird (longer neck ) has the defence role and is watching the photographer.  The cygnets have begun the moulting process that is 5-6 months long before they can fly.  Though omnivorous, grass and aquatic plants dominate their diet.  These cygnets are rolling fat, so fat that they have to lie down to continue grazing.

An advanced-age cygnet in the process of preparing to doze.  The variation in colour, and waterproofness of its feathers looks like failed camouflage and quite unappealing.  This change from the ugly and repellent to the beautiful and desirable bird was well captured in the (1844) Hans Christian Andersen story ‘The Ugly Duckling’.

Perhaps no longer to be called cygnets, these maturing birds have nearly completed the feather-change moult, but the small shape of their wings suggest that they cannot yet fly.  The leg band (middle bird) was attached by a group of Canberra bird lovers who actively track individuals and populations of swans.  Swans are valued by Australian society.

Not my photo, but I include it because of its importance.  This bird is not an albino, because it has pigmentation around its beak and eye.  Its white feathers are the expression of a rare genetic mutation.  So, it is a white Black Swan.  Hospital treatment was needed because of hunters, even though Black Swans are protected birds everywhere in Australia.

Black Swans live under a serious threat because they are ultra-susceptible, with  100% fatality, to Asian Bird Flu (aka HPAI – highly pathogenic avian influenza).  Genomics reveals that this ultra-susceptibility has developed because of their long (genetic) isolation.  So, if we fail to quarantine our island nation from HPAI, we will likely exterminate the iconic Black Swan.