172 BIRDS' NESTS 



we include the Australian iWagpie Lark (Grallina 

 australis) in the present family, although its affinities 

 are by no means clear, some authorities establishing 

 a separate family (Prionopidas) for its reception, we 

 have another bird-worker in mud of a still more 

 interesting character. The nest of this curious bird 

 resembles a massive cup-shaped earthenware vessel, 

 being built of mud or clay mixed with grass, bits of 

 stick and stems of plants, and even feathers, these 

 substances being used to strengthen and bind the 

 plastic mud together, much as human builders employ 

 hair to consolidate their plaster. No special efifort is 

 made to conceal this nest, which is generally placed 

 very securely on the upper side of some horizontal 

 branch, often one overhanging water. We shall again 

 have to refer to bird architects in mud, not only in 

 the present but in the succeeding chapters. These 

 workers in mud belong to various and distantly 

 related families, and show us, as we have so often 

 remarked before, how the nest-building habit has 

 been developed on almost precisely similar lines, not 

 only by remotely allied species, but in widely sepa- 

 rated parts of the world. Some of the Pies {Den- 

 drocitta) make shallow cup-shaped nests of a rather 

 flimsy description, in many cases at no very great 

 height from the ground in bushes. They are made 

 of fine twigs, stems of creepers and weeds, generally 

 with no lining, but occasionally with a scanty one of 

 hair, the fibrous roots of ferns and bamboos, and the 



