144 BIRDS' NESTS 



being lined with turf and moss. Our own Common 

 Heron {Ardea cinerea) constructs such a nest, and the 

 same type is used when it is situated on a ledge of a 

 cliff. Gregarious habits largely prevail amongst this 

 order of birds during the breeding season, and num- 

 bers of nests are built close together, not only in 

 trees, but on the ground in marshes. They are also 

 social birds, and very often several species may be 

 found breeding in the same chosen spot. We find 

 the same double type of nest amongst the Egrets, the 

 one being a platform-like mass of sticks and twigs, 

 sometimes with the leaves still attached, placed in a 

 tree or large bush ; the other equally bulky, but com- 

 posed of dead reeds and fragments of other aquatic 

 vegetation. The same remarks equally apply to the 

 Cattle Herons, the Night Herons, the Squacco Herons, 

 and so forth. Seebohm records that a peculiarity in 

 the nests of the last-named species and those of the 

 Little Egret {Ardca garzetta) and the Night Heron 

 {Nycticorax griseus) that he met with during a visit 

 to the great colonies of Herons in the valley of the 

 Danube was that all the twigs radiated from the 

 centre, but that those of the Common Heron were 

 built in the normal way, the sticks being arranged 

 round the centre in the form of arcs. The Bitterns 

 are more uniform in their type of architecture, 

 although even here there are occasional instances of 

 the dual form of nest. These birds are much less 

 social and gregarious than the typical Herons, gene- 



