310 THE ZOOLOGIST. 



territory, and when the young are fully grown the parents turn 

 on them and drive them away. It is only old males that ever 

 show any hostility to man, and then only at breeding-time, and 

 in exceptional cases at that. Both birds share the duties of 

 incubation, and copulation is performed in the water as well as 

 on land. The largest brood I have seen on the Thames was one 

 family of ten cygnets. As a rule, four or five is the number of a 

 brood. The eggs are laid at intervals of several days, and when 

 both birds are absent from the nest are covered with down and 

 grasses from the finer lining of the nest. Some years ago a 

 houseboat sank at its moorings one spring, and a male Swan 

 swimming by caught sight of its own reflection in the partly 

 submerged windows. For the next fortnight the bird spent the 

 whole of each day swimming to and fro from window to window, 

 giving fierce pecks and thrusts at his imaginary rival. If the 

 houseboat had not then been refloated, I think that bird would 

 have become a raving maniac among Swans. 



(To be continued.) 



