390 THE MUTE SWAN. 



food, which pleases them best, rather than fairly to crop and 

 swallow it. 



Consequently, there is no bird in the least comparable to 

 the Swan as an agent for clearing a pond of weeds. It does 

 not, however, eat all weeds indiscriminately j it seems scarcely 

 to touch the water-lilies, white and yellow, except perhaps in 

 a very young state, though it no doubt checks their increase 

 by seed. These, when too numerous, may be uprooted by 

 means of a long pole armed with an iron claw, and used either 

 from the shore or from a boat; once detached from their 

 moorings, they may be floated away. Swans seem to prefer, 

 first, what we call the lower forms of vegetation, the Con- 

 fervse and the Characeae, then the Callitricha aquatica, or 

 Water Starwort, and the long list of Potamogctons, or Pond- 

 weeds : the rhizomata of all sorts of reeds, rushes, arrow-heads, 

 &c., are greedily torn up and devoured. A lake of half an 

 acre in extent is quite large enough (with the assistance of 

 corn, refuse vegetables, and grass-clippings, when the weeds 

 run short) not only to maintain a pair of Swans, but to supply 

 an acceptable lot of fat Cygnets every autumn. Swans have 

 been kept successfully in a much more limited space. But in 

 one instance within my own knowledge, where the extent of 

 water is not a quarter of an acre, the annual brood, as soon as 

 they entered the pond in company with their parents, were 

 devoured by some enormous pet Pike that equally shared their 

 owner's favour a hint that one cannot breed Swans and fresh- 

 water sharks at the same time and place. 



The Swan, consuming the submerged refuse of plants, is 

 thus the scavenger of the waters, as the Hyaena and the 

 Vulture are of the land. In such countries as Holland, and 

 still more about the deltas of large rivers in the south of Europe 

 and western Asia, their influence must be very beneficial. In- 

 deed, we are compelled to believe that they have been bounti- 

 fully created to fulfil this office of cleansing the half-stagnant 



