THE PELICANS 2O5 



caves or dark holes alone, or at some distance from the nearest neigh- 

 bour. Gannets never, but cormorants and shags occasionally, shift 

 their colonies although usually remaining for several years in one 

 place; when they move they may not travel far from the previous 

 site, to which a few years later they may return. On the European 

 mainland cormorants frequently build in trees or cliffs near or over 

 fresh water, which they fish, but sometimes they build on the ground 

 surrounded by fresh or salt water. Some cormorant colonies may 

 number as much as 3,000 pairs, with other species, such as herons 

 and spoonbills, nesting among them (Holland); but there are no 

 cormorant colonies in the British Isles with a thousand nests. 



The display of the cormorants is more one-sided than that of 

 other sea-birds. Lewis (1929) considered that it was the male double- 

 breasted cormorant who initiated the breeding cycle, by taking up 

 position at the nesting site and displaying and croaking when the 

 female appeared. Selous (1927) thought that the female shag solicited 

 the male; and Portielje (1927) and Haverschmidt (1933) showed that 

 it was the female European cormorant that did so. As reversed coition 

 occurs, it is still open to doubt which sex of the European cormorant 

 displays most, and there may not be any hard and fast rule. In display 

 the tail is held up over the head at a sharp angle; the head is then 

 frequently shot forward with the bill open to exhibit the yellow mouth 

 with what has been described as a "feather-duster" effect. The head 

 may rest almost on the back, and the throat or gular pouch distended 

 and vibrated. The whole performance is quite violent and seems to 

 fascinate the watching bird, drawing it towards the performer until 

 coition takes place. Some promiscuity in the cormorant, and polyandry 

 in the shag, has been recorded, associated with this female display. 



Display in the gannet is mutual, while in the man-o'-war bird it 

 is the male who displays, ballooning his purple throat-sac as he builds 

 and guards the nest, while the large plain female brings him material. 

 And it is he who will perform the major part of incubation and brood- 

 ing. To a lesser extent Brandt's cormorant, Phalacrocorax penicillatus, 

 expands a gular pouch, which is a brilliant caerulean blue, in display 

 (L. Wilhams, 1942). 



The voice of the pehcan family is not exactly musical ; it consists of 

 harsh guttural notes, although the sexual note, uttered in coition and 

 fondUng, may be a pleasant crooning one. The young have a plaintive 

 "uk-uk-uk" note which is the forerunner of the adult "oak-oak" 

 of double-crested and European cormorants, shag and gannet). 



