This section is from the book "The Balance Of Nature And Modern Conditions Of Cultivation", by George Abbey. Also available from Amazon: The Balance Of Nature And Modern Conditions Of Cultivation.
Bewick's Swan (Cygnus minor or Bewicki) passes the winter in Britain and flies northwards in spring. Its length is about 4 ft.
It possesses an orange patch at the base of the bill, and is able to produce a very grating noise. This cry resembles the word "hoop," and is produced through the peculiar arrangement of the trachea or windpipe, and is also a characteristic of the Hooper or Whistling Swan (C. ferus), which has a slender beak, black at its tip and yellow at the base, whilst it wants the black knot or tubercle on the beak. This bird arrives in Britain in winter and departs in April.