Let us now consider a duckling, a downy Canvasback that has just 

 emerged from its shell. Shortly after its down is dry it ventures forth into the 

 world equipped with a remarkable set of actions with which it successfully 

 meets its environment. It can walk. The moment it touches water it swims. It 

 can dive under water. The complicated process of picking up an object with 

 its bill is readily accomplished. The initial actions are not learned movements ; 

 these are the duckling's endowment, its inborn heritage. The fact that a 

 bird hatched alone in an incubator accomplishes these same acts before it 

 ever sees another of its kind, or before it has lived to experience its environ- 

 ment is evidence that they are not learned. This we know as inborn, innate, 

 or instinctive behavior.* 



As the duck grows older there is a maturation of further instinctive acts 

 These begin to function as the time for their use arrives, just as the feathers 

 of the specific color pattern develop on a growth schedule. The act of flight, 

 for instance, is not learned. This is merely the development of an instinct 

 that will gain maturity when the primary feathers of the wing are fully 

 grown and the bird is physically ready to fly. Ducks raised in small pens 

 where flight was impossible were able to fly when first cast into the air. The 

 act of flight is as much a heritage as walking, but does not mature until the 



•Thorpe (1951a:3) explains that before about 1935 the term instinct "had tended to fall 

 out of use among biologists, while the psychological schools of behavior study tended to use it 

 for behavior which is: 1. Relatively complex; 2. Markedly constant and therefore presumed to 

 be inherited; and 3. Related to a situation rather than to locally-defined stimulus. In the last 

 15 years, however, comparative ethologists have been using the term in a much more precise 

 sense and have been finding it almost essential for their discussions. The attempt has been 

 made to formulate this more recent usage in the following definition: Instinct: An inherited 

 and adapted system of co-ordination within the nervous system as a whole, which when ac- 

 tivated finds expression in behavior culminating in a fixed action pattern. It is organized on a 

 hierarchical basis, both on the afferent and efferent sides. When charged, it shows evidence of 

 action-specific-potential and a readiness for release by an environmental releaser." Tinbergen, in 

 his book The Study of Instinct (1951:112), says that "it may seem a little early to attempt a 

 definition of 'an instinct'; yet in my opinion, such an attempt could be of value for future re- 

 search. I will tentatively define an instinct as a hierarchically organized nervous mechanism 

 which is susceptible to certain priming, releasing and directing impulses of internal as well as 

 of external origin, and which responds to these impulses by coordinated movements that con- 

 tribute to the maintenance of the individual and the species." 



15 



