150 BIRDS' NESTS 



them of coarse twigs. On Christmas Island the 

 Gannets have a very curious habit of breaking off all 

 the twigs within reach of their bill and dropping 

 them under the nests as they sit incubating. These 

 mounds were from one to two feet high, and in some 

 cases solidly cemented together by excrement. We 

 should mention that the nests in the latter locality 

 are made in shrubberies of low stunted bushes. As 

 another type of nest in this group we have that of the 

 Sula cyanops, which is also made on Christmas Island. 

 This nest is nothing but a slight concavity scratched 

 out in the fine coral sand, and might very aptly be 

 included in the series of crudest nest-forms. 



From the nests of the Gannets we pass to a con- 

 sideration of those of the Cormorants (Phalacro- 

 coracidae). These differ largely, even belonging to 

 the same species, not only in materials but in 

 position. The Cormorant (Phalacrocorax carbo) of 

 the British Islands, for instance, makes several types 

 of nest according to locality. This bird breeds not 

 only upon marine cliffs, small sea-girt islands and 

 reefs, but also on the ground and on trees and 

 rocks inland, miles away from salt water. When 

 near the sea, either on the ground or cliffs, it is 

 usually a pile of seaweed and stalks of marine 

 plants, the cavity lined with fresh green thrift, sea 

 parsley and campion, the whole structure being 

 from one to several feet high. When built inland 

 on cliffs it is generally as large and formed on the 



