THE VISUAL WORLD 



ing requirements of many Pintail hens, yet each must perceive variations in 

 the monotonous pattern that direct her to her own nest site. Laven ( 1949 ) 

 carried out an interesting experiment in nest-perception in the Ringed 

 Plover. This little shore bird nests on open beaches. When one encounters 

 a pair, it may be an hour or more before the nest can be located, even 

 though it is "in plain sight" close by. If we let our eyes stray from the nest 

 after it is found, it may be several minutes before the eggs are relocated, 

 so closely do they resemble their background. Laven removed eggs from 

 a nest, then obliterated the cavity and tracks nearby. Even so, the birds 

 found the site without difficulty. But when he changed the nature of the 

 environment to a distance of three meters around the nest by leveling it 

 off, the plovers were disoriented. They must have followed visual cues pre- 

 sented by the whole of the local landscape. I presume this applies to nesting 

 ducks, for even when the nesting cover has been removed by fire or mow- 

 ing, I have seen hens return to their nests, guided there, probably, by cues 

 presented by the landscape patterns beyond the immediate vicinity of the 

 nest. 



Canada Geese are interesting subjects to study because they are so re- 

 sponsive in voice as well as in action. The flock of Canada Geese at Delta 

 is, so to speak, a part of the little community. The birds live but a few yards 

 from our homes and offices ; we watch them, as they watch us, many hours 

 a day. Our normal human activities are accepted without "comment" by the 

 geese. When I walk past the pen they do not seem to notice me; but when 

 I pick up a large box from the truck and carry it on my shoulders to the 

 hatchery, the geese lift their heads high, and give voice as evidence of their 

 awareness of something new. One brisk September afternoon I noticed the 

 birds suddenly alert, all looking toward my house, many of them uttering 

 the gutteral notes of disturbance. In the first autumn chill my son Albert 

 had donned his new red, white, and blue hockey sweater which he had 

 never worn before. Here, suddenly, was a bright, strange thing against the 

 landscape. The geese noticed it immediately. They watched for several 

 minutes, then resumed their feeding, never again to react to the sweater. 



Where, as with geese lifting their heads to a man carrying a box, there 

 is a sharp response to the object seen, the valence of the object is established 

 by the birds' behavior. Indeed, it is only by the birds' action that we can 

 measure and study their awareness of the components of their environment 

 But action surely is not the only criterion of awareness. For example, I step 

 from the hatchery to the pond side where the geese are resting and not 



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