Swanfest ... Bewick's and Whoopers ... sights and sounds ...

On my third visit to Slimbridge this winter the Bewick's Swans gave nice views as they lingered on the Rushy Pools ... calling gently all the while before flying off onto the more distant and mist enshrouded fields by the Severn Estuary ...

... some left singly and others in twos and small groups from where they had been by the pools ...

... it was interesting to notice the structure of the calls and how they differed from Whooper calls ... the Bewick's having a higher pitched and gentler call with a distinctly musical quality ... each note rising then falling in pitch in a way that reminded me of Eider or Mediterranean Gull calls ...

Bewick's Swan was not recognised by science until 1830, some two years after Thomas Bewick's death ... a number of prominent ornithologists of the day had a hand in establishing the distinction from Whooper Swan and answered the question as to why some 'Wild Swans' were so much smaller than others ... Richard Wingate, a Newcastle taxidermist described the species in 1829 and in 1830 P.J.Selby named it Cygnus Bewickii of Wingate although William Yarrell is credited with being the original describer ...

Woodcut by Thomas Bewick's son.

But the story goes back further ... Bewick's Swan is now recognised as a subspecies of Trumpeter Swan Cygnus columbianus , described by Ord in 1815 but now renamed Cygnus buccinator ... giving credit to the Trumpet concept ( the buccinator muscle in our cheek being used famously by trumpet players ) ...

Interestingly, such nineteenth century commentators such as Saunders and Morris tell us that Bewick's Swan was rare in England but present in Scotland and Ireland in flocks of several hundred ... a striking contrast with today's predominantly south eastern distribution ...

So, with the sights and sounds of Bewick's fresh in the memory, some Whooper Swan experiences were on the cards ... and what better place than Caerlaverock ...

... the birds were in good voice ... and none of the musicality of the Bewick's ... the notes were deep, harsh and lacked the changing pitch ...

The sonograms show the grouping of notes into threes and fours, the constant pitch and low frequency of the Whoopers ...

... and the mainly two note calls of the Bewick's with their charmingly rising and falling notes of a higher pitch ...