66 HOMING AND RELATED ACTIVITIES OF BIRDS. 



other. She was driven off five times and each time returned and took the eastern nest. 

 As she always approached from the southeast it is probable that the direction of approach 

 determined the choice. 



The western nest and egg were next moved 11 inches to the eastward, 8 inches farther 

 from the original nest site than the former eastern nest, which was left undisturbed. The 

 bird returned and took the new nest. The western nest was again shifted to the eastward. 

 The bird returned and again took the eastern nest. By shifting the two nests alternately 

 it was possible to move them 4 feet to the eastward without confusing the bird. Each time 

 she chose the eastern nest in preference to the former eastern one which she had just occupied. 

 But when the nests were brought near the bushes the bird began to show signs of dissatis- 

 faction, finally returned to the original nest site, and settled down there. After a time she 

 got up and went back to the two nests. This time she covered the western one. The 

 nests were then shifted, a foot at a time, to the westward, the bird each time choosing the 

 western one, until they were near the water, 4 feet west of the original nest site. Here 

 the bird again became dissatisfied and returned to her old nest. The eggs were finally 

 placed 8 inches east of their first position and left for half an hour. At the end of this 

 time the bird had rolled one of them to the original nest site and was brooding it there. 



In approaching the nest the bird alwaj's flew along the shore skirting the fringe of bushes, 

 then alighted about 6 feet southeast of the nest and walked directly to it. At various times 

 during the experiment she started from the alighting place straight toward the original nest 

 site, but turned aside to the new nests before reaching the old position. The movements of 

 her head indicated that she took her bearings from some object to the northward. What 

 that was I could not discover. 



It was found here that recognition of a nest is to some extent dependent 

 upon the relative positions of the nest and other objects in the neighborhood, 

 in this case an artificial nest. Other factors not brought out by the experi- 

 ment seem, however, to play a still more important part in orientation. The 

 constant alighting place and path to the nest furnish a clue to other factors in 

 orientation which appear more strikingly in other experiments. 



Experiment .5. 



A nest in an open space (at o in figure 1, plate 7) near a short stake (/) was obliterated 

 and replaced by two nests a foot apart. The bird chose the northern egg. Both eggs were 

 moved a foot to the northward. The bird alighted and chose the northern egg without 

 hesitation. Her mate came and covered the southern one. Both were driven off. The 

 first returned and alighted at a place 4 feet to the eastward (</), then walked for 3 feet straight 

 toward the original position of the nest. When still a foot away she seemed to catch sight 

 of the eggs in the new position, turned sharply from her course, and went straight to the 

 northern egg (d). She soon became dissatisfied, went back to her alighting place (g), and 

 returned to the northern nest, but this time directly. She then went to the southern nest 

 (6), returned to the northern, and covered the egg. Her mate came back and again took 

 the southern nest. 



Both nests were again moved, with the stake, 2 feet to the northward. The first bird 

 ahghted as usual near the bushes (g), walked to the original nest site (a), looked about, 

 and went directly to the new southern nest (c) . Her mate came and walked about the old 

 nest site. She got up and went to him, then returned to the nest. 



The stake was then moved back to its first position (a), the nests being left undisturbed 

 in the northern position. The first bird came to her alighting place and started directly 

 toward the new site, then seemed to catch sight of the stake and turned toward it, then 

 back to the ahghting place, toward the stake, back again to the ahghting place, again toward 

 the stake, then to another nest, where she seemed to get her bearings, toward the new nest, 

 toward the alighting place, then finally to the new nest. The path followed is indicated in 

 figure 3, and shows clearly the struggle between the motives offered by the sight of the 

 stake and that of the egg. 



The egg and stake were next placed 2 feet south of their original position (at h, in figure 1, 

 plate 7). The bird returned to her ahghting place (g), looked about, and went straight to 

 the new nest. The egg and stake were then moved to a position near the ahghting place 

 (e in figure 1, plate 7). The bird alighted 2 feet north of the stake, went to it, and covered 

 the egg without hesitation. 



