THE PELICANS 201 



the sight of this food, into which it dives and so becomes entangled, 

 and after a vain struggle may be drowned before the net is brought on 

 board. A net may take many hours to be completely hauled, depending 

 on its length and the amount of fish taken. It is extremely unlikely 

 that the gannet dives and swims to a greater depth than fifty feet. 

 The cormorant and shag, which fish in shallow water, remain longer 

 under the water (cormorant, 20/71 seconds; shag, up to 170 seconds, 

 with an average of 53 seconds: Handbook of British Birds, IV, 1940). 

 The gannet rarely remains under the surface longer than ten seconds 

 and often much less; in this time it could not possibly reach a depth 

 of 180 feet. Dewar (1939) finds that diving birds spend half the under- 

 water time in going down and up, and the other half in fishing below. 

 The rate of descent of coot and duck was i and i\ feet per second. 

 Gannets, plunging from a height, would descend a little faster. No, 

 the dive is short and shallow, and if it is unsuccessful the gannet 

 rises into the air immediately to gain height for a fresh dive. The 

 gannet and brown pelican, naturally very buoyant owing to the sub- 

 cutaneous cellular tissue of the neck and upper breast, which is auto- 

 matically filled with air before diving, do not usually dive from a 

 floating position.* They float much higher above the water in 

 swimming than do the cormorants. They are fast swimmers on the 

 surface, and also underneath, when the wings may be used to prolong 

 the dive and beat along the sea-floor (Kay). Before touching the 

 water in their power-dives the brown pelican partly, but not quite, 

 folds its wings; slow motion films have proved that the wings of 

 the gannet are stretched back, unfolded, behind the body. It is 

 generally believed that the wings are not used under water until 

 the impetus of the dive is expended and the diver has seized, or failed 

 to secure, its prey. The wings are then half opened as the bird comes 

 to the surface, and typical flight motions of the wings may take place 

 almost before a gannet has breached the surface. It resumes the search 

 for fish, usually flying about thirty feet above the water, but when- 

 shoals are at the surface it flies very much lower, moving slowly and 

 frequently diving slantwise. 



All species of the pelican tribe, after gorging themselves with 

 fish at a rich feeding-ground, may form quite large parties flying close 

 together in irregular lines and chevrons on the return to the breeding 

 or roosting grounds. Gannets and boobies, which have a thick plumage 



*But may do so if a shoal is at the surface, when, with head under water to 

 look for the fish, a gannet will dive, guillemot fashion, wings half open. 



