MUTE SWAN. 79 



tint on the white feathers placed by Mr. Kitton in 

 water in contact with red crag, is particularly inter- 

 esting-, as it corresponds exactly with the colouring so 

 often remarked on the necks of domestic swans — just 

 so far as they are usually submerged in feeding — occa- 

 sioned more probably by the water than by actual 

 contact with the soil. 



The beak in this species varies in colour with every 

 stage of growth from the nestling to the fully adult. 

 The cygnets in their first autumn have this feature 

 of a deep lead colour, the nostrils, nail, and marginal 

 line of the upper mandible being black, as in old birds. 

 As they assume their white plumage a lighter grey 

 tinged with green takes the place of the lead colour, 

 but up to the autumn of their second year they are 

 termed "blue beaks." Before the close of that year, 

 however, the dark tints have gradually given way to a 

 pinkish flesh colour, and in the following spring the 

 beak becomes orange red, the last proof of maturity, 

 the orange predominating in the oldest birds. In the 

 females the colours are somewhat less vivid than in the 

 males. The development of the frontal knob or *^ berry" 

 is a matter of age. This very marked feature of the 

 mute swan is extraordinarily developed in very old 

 males, but is always smaller in females. The difference 

 of sex is also distinguishable in the water by the females 

 swimming less buoyantly, by their necks being some- 

 what less robust, and by their more subdued, though 

 scarcely less graceful, movements. The hen bird, I 

 have noticed, commences the autumn moult earlier than 

 the male, and is usually in perfect plumage before her 

 mate has shot his old and ragged quills. 



Eiich had at one time a pair of swans which re- 

 gularly hatched, out of their usual number, two cygnets, 

 having the down of a decided blue tint instead of greyish 

 brown; and these retained their distinctive colouring 



