74 
STERNID.E. 
of the back of the Caspian Tern, have a peculiarly beautiful 
effect, where a party of these gigantic Terns are met with 
together ; but their bulky head, and proportionally short tail, 
are a certain drawback from the elegance of its general 
appearance. 
The movements of this species are by far less animated 
than those of others of its family : flying seems to be its 
usual exercise, in which it most excels ; it swims better than 
other terns, and runs with ease and swiftness; and when it 
has need of rest, this bird reposes on the ground. 
This Tern is sociable towards its own species, but does 
not frequent the society of other birds. By nature the 
Caspian Tern is shy, and always on the watch, and con¬ 
sequently not easily approached, except during the breed¬ 
ing-season. It is probable that terns and gulls associate 
purposely together, during the breeding-season, in order to 
protect themselves from the intrusion of other neighbours; 
for while most of them leave their nests during the day 
to feed, some remain at home, apparently to watch and 
give notice of danger, which they do by uttering their cries 
in case of need, to recall reinforcements. The present species 
would, at all times, rob the eggs and young of other birds if 
this wise arrangement did not exist, from whence the Caspian 
Tern has obtained its local name of Robber Tern. 
The call-note of the present species sounds like that of the 
common heron, being equally harsh and inharmonious; the 
bird utters it chiefly during its migratory journeys, but at 
other times only occasionally, or when provoked. 
The entire length of the Caspian Tern is twenty-one 
inches ; the beak, from the forehead, two inches and three- 
quarters ; the tarsus, one inch and a half; the tail, six 
inches ; the wung, from the carpus to the tip, sixteen inches 
six lines. 
