THE PELICANS 207 



such gatherings of gannets in immature plumage occur in August and 

 September, Having familiarised itself with the territory and even 

 built a nest and paired with a bird of the opposite sex late in the summer, 

 the young adult may spend one or more summers in this adolescent 

 fashion before successful breeding begins. But once the bond is formed, 

 probably it persists for life — at any rate the fully mature birds appear 

 to be paired on arrival early in spring. It becomes a habit to meet 

 at the nest, with all its associations of stimulating contact and 

 ceremonial — and eventually of consummation. More research by the 

 marking of individual gannets is however needed to confirm the 

 invariableness of this life-partnership of this long-lived sea-bird. 



Having settled upon the nest in the early part of the season, at 

 least from late February onwards, one or other of the pair of mature 

 gannets will not leave it until the following July or August, when the 

 young bird is sufficiently well grown to be able to defend itself from 

 enemies. This alternate watch, by male and female is very necessary; 

 the human observer who enters and disturbs a gannetry will notice 

 how the first birds to return to their nests take the opportunity of the 

 absence of immediate neighbours to steal as much nesting material as 

 possible. The dry grass, seaweed and flotsam is grabbed from the 

 unoccupied nest by the extended bill of the sitting bird and added to 

 the robber's pedestal. 



There are other dangers to which the nesting-site is exposed when 

 an adult is forced to leave the nest by the human intruder. In many 

 colonies there are predators, chiefly great and lesser black-backed and 

 herring-gulls, ready to pounce upon an egg or chick left undefended. 

 These gulls act as scavengers to the colony, and are in constant attend- 

 ance at many gannetries, and at cormorant rookeries. When disturbed 

 by human visitors gannets freely, and cormorants sometimes, disgorge 

 the undigested fish in their gullet before flying away. Young birds 

 do the same, although they may be unable to fly; but if old enough 

 they will shuffle out of the nest with cries of distress. This disgorging 

 is probably an automatic reaction due to fear, but it has the useful 

 result of lightening the bird for flight. The gulls eagerly snatch up the 

 ejected fish, which they appear to prefer as food to the egg or very 

 young gannet. The gull which takes an egg from the nest of a gannet 

 which has taken flight to escape a human trespasser may open it and 

 eat it in the nest, or may carry it away. Only the youngest gannets, 

 in their naked black stage, are devoured, and they may be gulped down 

 whole by the gull. These, then, are excellent reasons why the adults 



