THE BLACK TERN 85 



Its habits are very similar to those of allied birds. 

 It spends most of its time in the air, gracefully 

 flitting to and fro, dropping every now and then 

 to the surface of the water to pick up some food. 

 When on migration it may be seen flying along 

 shore, but at other times it prefers to frequent 

 fens, salt marshes, and swamps, and large sheets of 

 water where the shallows are choked with reeds 

 and rushes, and the alder trees form almost im- 

 penetrable thickets. At all times of the year it 

 appears to be gregarious, and during summer lives 

 in colonies of varying size to rear its young. The 

 food of this Tern consists largely of insects, small 

 fish, and other aquatic creatures, worms and grubs. 

 The note is a shrill crrick, sometimes prolonged 

 into crree. The nests of the Black Tern are made 

 amongst the reeds in the shallow water, or on 

 clumps of sedge and grass on the spongy ground 

 of the surrounding marshes. They are bulky 

 structures, like heaps of decaying vegetation, made 

 of rotten reeds and sedges, and the hollow lined 

 with dry grass. The eggs are three in number, 

 and vary from buff" to olive brown in ground 

 colour, heavily marked with reddish brown, 

 blackish brown, pale brown, and grey. Both 

 parents assist in their incubation. When disturbed, 



