SOCIAL AND SEXUAL BEHAVIOUR iG/ 



the close contact of the rearing period as it receives affection, protection, 

 and guidance from the aduk. Every action of feeding and preening 

 of the young by the parents strengthens the family (social) bond — 

 an experience to be of value later in the bird's life. The chick learns 

 to associate food and protection with others of its kind. Gradually 

 it learns to recognise individuals, first of all, its parents; although it 

 may not distinguish their sex at this stage it probably recognises them 

 as individuals by their individual behaviour, as for example when the 

 male gull feeds the female who in turn feeds the chick. 



So far it has learned to associate its parent's bill with the pleasant 

 sensations of feeding and grooming. How does it acquire knowledge 

 of danger, for soon it must learn that only its parents are not its 

 enemies? Danger is usually indicated by the warning-notes and 

 flight-actions of the adult, the chick's response to which seems to be 

 at first due to instinct, or maturation of instinct, rather than to any 

 process of learning. Young gulls, though precocious and born with 

 their eyes open and able to walk, do not crouch or hide on a warning 

 signal until they are two or three days old. Young gannets, born 

 blind and naked and with a more embryonic brain than the gull 

 chick, do not strike at intruders (when, with warning cries, the adults 

 leave the nest) until their eyes are open and they are covered with 

 the first down. As the brain develops however, learning is mingled 

 with maturation of instinct, and adaptability to new situations is 

 acquired. 



At fledging time the young sea-bird discovers that its parents are 

 growing indifferent to its food-begging advances, and wdll ultimately 

 repulse them, or will abandon the chick completely (tubenoses, 

 gannets and puffins). In some species of social gulls the adults not 

 only become hostile but, unless the young bird retreats, will actively 

 attack and kill it. Thus sociality, which is not proved to be innate 

 (no hormone for gregariousness has been demonstrated in studies 

 of the endocrine organ of a bird), receives its first serious check, and 

 the family bond is broken. To minimise the attacks of the adults the 

 juvenile sea-bird learns to keep at least one body's length (striking 

 distance) from a neighbour; and a pattern of behaviour is acquired 

 which enables the bird not only to retreat at the aggressive display 

 of the adult, but to employ the same threat signals to drive away 

 birds younger or weaker than itself. By this device — usually a lowering 

 of the head, pointing of the bill (mouth sometimes open) and raising 

 of the neck- feathers — it is able to take its place in the community. 



