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When Kevin McLaughlin and I saw this swan at Bluffers Park in
Toronto on 29 January 2011, we noticed with amazement its bright
orange-yellow legs. Since it bore a yellow tag number H11, we
surmised it was a Trumpeter Swan. Except for its leg colour, it fit
Trumpeter Swan in every respect.
To find out more about this mystery swan, I talked to Harry Lumsden,
Ontario’s Trumpeter Swan expert. Harry told me that H11 is a
leucistic female Trumpeter Swan, about three years old, spending
most of its time at Bluffers Park where it hatched and is the only
survivor of its parents. H11’s female parent still lives, however
the male parent died recently. Leucism is caused by a single
recessive gene that must be carried by both parents.
There are two colour morphs of the Trumpeter Swan, a normal morph
and a very rare leucistic or white morph.
In Ontario there are currently only two known leucistic Trumpeters
out of 652 (winter 2010-2011 inventory): the former pair at Bluffers
Park produced one - H11 and a pair at Aurora produced one, which
still lives. A pair on Big Rideau Lake produced two or three
leucistic offspring about 10 years ago but they are no longer
around.
H11 has a normal adult all black bill, however when it was younger,
it showed other characters of leucism. As a cygnet during its first
year of life its bill was
orange-yellow, unlike a normal Trumpeter cygnet’s bill which is pink
at the base with dark grayish black towards the tip. When H11 was a
cygnet, it had a white plumage and yellow legs and feet, whereas
normal cygnets are grey and their legs and feet are grayish pink.
Leucism also occurs in Tundra and Mute Swans. It is very rare in
Tundra Swans, which can have pale blue eyes, yellow, orange, pinkish
or red legs, and red bills, but is more frequent in Mute Swans,
expressing itself as the white morph in cygnets, which remain white
as juveniles and adults. The legs and feet of white morph Mute Swan
cygnets and juveniles are pinkish tan, and in adults are greyish
pink.
Next time you visit Bluffers Park in Toronto, look for this rare
leucistic morph of the Trumpeter Swan. |
