AWARENESS OF DIRECTION 



pletely with overcast skies. . . . The homeward orientation of Lesser Black- 

 backed Gulls in sunny conditions gave place to disoriented scatter in 

 heavily clouded and overcast conditions." Matthews found disorientation 

 under cloud in the Manx Shearwater, and he says that "it was possible to 

 show, further, that the same individuals which gave good orientation in 

 sunny conditions would scatter at random with overcast, and vice versa." 



This initial orientation does not hinge on the bird's familiarity with 

 the range about its home. Matthews (1953b) observed an awareness of 

 the direction home in untrained young pigeons which had been allowed 

 to fly only in the immediate neighborhood of their loft. Set free one by 

 one at distances of 50 to 75 miles from home, they showed an awareness 

 of the direction home that was but little inferior to that of experienced 

 birds, although their success in returning was not so high as that of birds 

 with training. Kramer and Saint-Paul ( 1954 ) went a step further, keeping 

 their pigeons in large aviaries within which they had limited flight experi- 

 ence. Given their freedom 320 kilometers (about 200 miles) from home, 

 these inexperienced birds showed a direct homeward orientation at the 

 point of release, although, like Matthews' birds, their homing success was 

 not so great as that of trained individuals. 



There is before us, then, the evidence that some birds are able to orien- 

 tate directly homeward from strange locations and that such direct initial 

 orientation operates only when the sky is not hidden by cloud. The impli- 

 cation is clear that the sun serves as a cue to the direction toward home. 

 If this is so, the displaced bird must be aware of the arc angle and sched- 

 ule of the sun as these are relative to the situation at home. 



It has been observed in many homing experiments that some birds re- 

 leased in strange country, far from home, orientate homeward more pre- 

 cisely and return at a greater rate of speed than others set free at lesser 

 distances from home. Wojtusiak (1949) felt that the birds that were closer 

 came back at a proportionately slower rate because of their self-confidence 

 within the range of familiar surroundings. Griffin (1943), noting the poor 

 homing of Herring Gulls when released close to home, said that "if this is 

 a consistent effect it might conceivably offer a clue to the fundamental 

 problems of homing." In the light of Matthews' sun-navigation hypothesis 

 this failure of birds to return from strange but near places might be due 

 to their inability to perceive changes in the arc angle and schedule of the 

 sun close to home. Perhaps birds, like men, must travel some distance be- 

 fore they become aware of the sun's changes. Until they have been car- 



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