TRAVELS OF WATERFOWL 



innate reactions to the features of the country. The young birds went into 

 the water spontaneously and swam out even if they were not conducted 

 into the water. Young tufted ducks and shovellers which are left to them- 

 selves were — even when newly hatched — strongly attracted to reeds, where- 

 as young eiders avoided reeds and instead were especially fond of swim- 

 ming along open rocky shores." Mayr remarks (1942:246) that "naturalists 

 have always marvelled at the unfailing accuracy with which animals can 

 find the right ecological niche to which their species is adapted." And 

 Thorpe suggests (1949:86) that "one can safely assume that, quite apart 

 from the recognition of a particular locality, birds can recognize the right 

 type of environment for themselves. If this were not so, every year would 

 find birds trying unsuccessfully to breed in all sorts of unsuitable places. 

 This recognition of an environmental type may be very largely the result 

 of experience, but it is in line with the modern concepts of instinctive be- 

 havior to assume that there may be an innate hereditary, primarily visual 

 recognition of the right type of environment." 



The valence of certain components of the bird's visual world hinges on 

 time and condition. Thus the Mallard drake on his breeding territory dis- 

 tinguishes between migrant Mallard pairs passing overhead and resident 

 pairs that threaten to alight on his domain. The former draw no response 

 from him, but the intruders are driven away. He is aware of behavior 

 differences by which sexual intruders are distinguished from passing mi- 

 grants of the same species. Perception of these differences depends upon 

 the drake's position in the sexual cycle. A few days earlier he was a gregari- 

 ous being and perceived all Mallards as companions; a few weeks later this 

 will be true of him again. 



As we watch a gathering of spring transients at the edge of the ice on 

 Cadham Bay, we notice two Canvasback drakes that go about their busi- 

 ness without paying the slightest attention to the females of close-by pairs 

 of Canvasback. But suddenly a hen of their kind, followed by three drakes, 

 alights. Immediately the unattached males join this courting group. Here is 

 selection and rejection hinging on physiological condition. The unmated 

 drakes ignore the paired hens but pursue the single female. The mated 

 drakes disregard the single hen to remain at the sides of their own mates. 

 Every sexually active duck accepts or rejects those of its companions which 

 its sexual status directs it to acknowledge or ignore. This calls for sharp 

 awareness of behavior. The lone drake must perceive the difference in be- 

 havior between a mated and an unmated hen. The Mallard must distinguish 



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