ized predator of a species shows little or no habitna- 



Conditionintj is a form of learning and consists of 

 the establishment of a connection between a normal 

 reward or punishment and a new stimulus, that is, 

 one that hitherto has had no meaning to the animal. 



Imprintiny is especially well shown in waterfowl 

 and gallinaceous birds. Grey-lag geese reared from 

 the egg in isolation react to their human keepers, or 

 to the first relatively large moving object that they 

 see. as they would the parents by following. This 

 imprinting of the parent companion is confined to a 

 very definite and usually very brief period following 

 shortly on emergence from the egg. Once thoroughly 

 established, the behavior is very stable, if not totally 

 irreversible. Furthermore, this imprinting of a hu- 

 man being as a substitute for its own species will call 

 forth, a year or more later, sexual reactions to man 

 in the mature bird. There is no innate recognition by 

 birds of parent, species, se.x, or home locality, but 

 there is evidence that these are learned through as- 

 sociation and contact during the course of develop- 

 ment. Imprinting doubtlessly also occurs in other 

 animals than birds. 



Imitation is another form of learning. An indi- 

 vidual in a flock or herd may start to feed or run 

 when it observes other individuals feeding or run- 

 ning. A young animal learns much that is traditional 

 of the species by imitating its parents. Vocal imita- 

 tion is conspicuous in the elaborate songs of some 

 birds. 



Trial and error learning involves trial responses to 

 a variety of stimuli with gradual elimination of all 

 responses and stimuli except the relevant ones. A 

 chick pecks at random at all sorts of objects until it 

 accidentally strikes one which is edible, whereafter 

 the chick has a greater tendency to peck at objects 

 that have a similar appearance. Repetition of the 

 same act usually leads to the formation of a habit. 

 Habits often appear stereotyped but differ from in- 

 stincts in that they have to be learned and are not 

 inherited. 



Insight learning involves an apprehension of rela- 

 tions and the sudden adoption of an appropriate re- 

 sponse without previous trial and error behavior. 

 The mason wasp of India builds a cluster of clay 

 cells. After depositing an egg in each cell, the female 

 fills it with caterpillars and seals it with a lid. Even- 

 tually the whole cluster is covered with a layer of 

 clay. While a wasp was away hunting for its prey, 

 an experimenter made a large hole in the side of a 

 cell. On its return, the wasp put in a caterpillar 

 which fell out through the hole. A second caterpillar 

 stuck in the hole with a large part hanging out 

 through it. When the cell was completely provi- 

 sioned, the wasp appeared to notice the hole for the 

 first time and carefully examined it. With great and 



FIG. 2-7 Courtship «nd maflng behavior of the three-spine 

 sticitlebecit (after Tinbergen 1951). 



The general nature of responses 15 



