TRAVELS OF WATERFOWL 

 one moves. A moment later a stranger steps out and the geese lift then- 

 heads to acknowledge his entry. If I walk toward them they hold their 

 ground; if the stranger approaches, they retreat. They respond directly to 

 the stranger, but they are aware of me and their very lack of action is evi- 

 dence of this. On the pasture I have often stood among the cattle during 

 the evening stubble flight. The ducks come low over the grazing beasts, but 

 flare upward when they pass over me. In their action they acknowledge me 

 as an enemy even though I have not moved; but their lack of response to 

 the cattle surely cannot be evidence that they do not perceive these animals 

 as harmless components of the scene. 



Watching the daily travels of waterfowl, we see them moving in a famil- 

 iar environment. It is clear that each bird recognizes the various aspects of 

 its range — the nesting meadow, the slough, the Station pond, the edge of 

 Cadham Bay. We see them approach these from different directions, travel- 

 ing by different routes as the wind varies. They must perceive the parts of 

 their range as familiar from many visual aspects. Yet the home range of a 

 duck, I suspect, is not made up of so many discrete objects or landmarks; 

 the bird probably reacts to the whole of its familiar visual world. 



Various portions of the range may have valence according to time and 

 condition, the nesting meadow, the sand bar, the slough each being per- 

 ceived according to the individual's physical requirements for these places. 

 In local travel only proximate patterns have valency. In the flight to stubble 

 much more of the landscape may be important to orientation. In long travels 

 and in migration, the sun or sky-brightness, cloud formations, or (at night) 

 the moon and other heavenly bodies may be perceived, not as discrete 

 guides, but as parts of the whole. When a duck has become lost, however, 

 as in a storm or in a flight over unfamiliar terrain, one isolated part of the 

 visual world may then have valence. Thus a duck flying over strange, dry 

 prairie responds abruptly to the shimmer of sun on water; a goose flying 

 over unbroken forest reacts directly to the silver streak of a river interrupt- 

 ing the solid green of spruce. Then, perhaps, the relation between the bird 

 and one single part of the environment is of much the same order as the 

 mechanism of the social releaser. And just as the response to the social re- 

 leaser may lead to error (as Snow Geese joining white rags), the bird often 

 errs in its response to single parts of the environment. Each year many water 

 birds alight on wet roads. Ducks and geese are able to take wing after dis- 

 covery of their mistake, but annually large numbers of loons and grebes 

 are stranded where they have alighted on highways far from water. 



44 



