LIFE HISTORIES OF NORTH AMERICAN PETRELS AND PELICANS. 225 



tial and a prenuptial molt in older birds. There is much individual 

 variation in the time required for the various changes. 



The adult gannet undergoes a complete postnuptial molt in August 

 and September, which is sometimes prolonged into November, and 

 a partial prenuptial molt, involving the contour feathers and per- 

 haps the tail, during March, April, and May. There is no conspicu- 

 ous seasonal change in plumage, except that the yellow suffusion on 

 the head is richer and more extensive in the spring and is much paler 

 or entirely lacking in the fall. 



Food. — The food of the gannet consists entirely of fish, which it 

 obtains by diving in a most spectacular manner. A flock of feed- 

 ing gannets bombarding a school of herring is a most interesting 

 sight and not an uncommon sight on the New England coast late in 

 the fall. At that season a few gannets are almost always in sight 

 circling high in the air off, the coast, looking for migrating schools 

 of fish. As soon as a school is discovered and one or more gannets 

 begin diving, others begin drifting in from all sides, until, in an 

 incredibly short time, a great cloud of birds has gathered; how the 

 welcome news is transmitted so quickly and so far is a mystery ; where 

 less than a dozen gannets were in sight a few minutes before, there 

 are now two or three hundred. Over the unlucky school of fish is a 

 bewildering maze of soaring, circling birds, pouring down out of 

 the sky in rapid succession, plunging into the water like so many 

 projectiles and sending coliunns of water and spray many feet into 

 the air like the spouting of a school of whales. In the center of the 

 mass are the plunging birds hurling themselves at their prey with 

 tremendous force ; all around them on the water are the birds which 

 have just risen to the surface to swallow their prey or to rest before 

 trying again and in the air birds are constantly rising, circling, and 

 soaring for the next plunge. It is a lively scene for a while, but it 

 does not last long, as the fish soon become frightened and seek safety 

 in the depths, when the gannets scatter to look for another school. 



Dr. Charles W. Townsend (1905) describes the process in de- 

 tail as follows : 



The gannet flies rapidly over the water and begins to soar at a height of from 30 

 to 100 feet, often rising just before the plunge. At the plunge the head is pointed 

 down, the tail up ; the wings are partly spread so that the bird appears like a 

 great winged arrow. The speed of the descent is great, and the wings are closed 

 just before reaching the water, which spurts up to a height of from 5 to 15 feet. 

 After the waters have subsided following the splash and all is still, the bird 

 suddenly and buoyantly comes to the surface, the head and neck stretched out 

 first. It then sits quietly on the water for half a minute or so to finish swallow- 

 ing the prey and to rest, and then slowly and laboriously rises to windward, 

 with its long neck and taU stretched to their full extent. Gaining a height of 

 thirty or more feet, it swings around to leeward and is soon soaring and plung- 

 ing again. Of eight observations made with a stop-watch on the length of time 

 that this bird remained under water after the plunge, the limit was 4 and 7 



