KEEL-BREASTED BIRDS. 245 
under water after their prey (Fig. 280, 3). The common 
tern (Fig. 280, 2) (Sterna hirundo) is found in Europe and 
North America. The bill is long, slender, and pointed, 
the tail long and forked. The nest is a mere depression in 
the sand, three spotted eggs being laid in each. During 
the day the sun warms them, the mother performing her 
office only at night. The roseate tern is a familiar form. 
The Noddy Terns (Azous stolidus) have a wide geo- 
graphical range. They are mild and beautiful creatures. 
At Tortugas they erect rude nests composed of twigs of 
bay-cedar dropped together upon the bushes, upon the 
top of which is laid the single, nearly white egg. At St. 
Paul’s Rocks the noddies build a fanciful nest of sea-weed, 
cemented together and attached to the rock, a lace-like 
fringe hanging down all around. Upon this platform or 
bracket the single egg is placed. 
The Laughing Gull (Zarus atricilla)* is found upon 
the tropical and temperate coasts of North America. 
The Arctic Tern (Sterna macrura) is the only suc- 
cessful enemy of the skua, pursuing it with extreme ferocity. 
Its eggs are deposited among the stones and mimic the 
lichen-covered pebbles, this protective mimicry being car- 
ried out in the downy young. 
The most powerful of the gull family is the skua (Sver- 
corerius). It has a wide geographical range, the various 
species being found in the Arctic and Antarctic regions 
of various countries. 
The Parasitic Jager, of the Arctic region of Europe 
and North America, follows terns and gulls, forcing them 
to disgorge their prey. 
The Antarctic Skua (S. Améareticus) has all the qual- 
* At Tortugas they follow the brown pelican, systematically rob- 
bing it, When the latter tosses a fish preparatory to swallowing it, 
the laughing gull with its victorious ‘' Ha-ha !” alights on its back, leans 
forward and snatches the morsel and flies away, generally to be robbed 
in turn by the man-of-war bird (Fig. 283). 
