192 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 2. NO. 4. 
found plentifully on the same feeding ground." (36). Do not cases 
of this kind give us rather striking evidence that the food supply 
of the south is limited? 
We have thus two areas in the geographical distribution of 
birds that are deficient in food at . opposite seasons of the year^ 
and we can see readily enough the cause for migration both in 
the spring and in the fall. 
It is still a quite general belief that love of home and nesting 
ground is among the important factors causing the spring migra- 
tion. Ornithological literature contains innumerable references- 
to cases where birds have returned year after year to the same 
locality or even the same tree or the same box. Prof. Newton, in 
discussing this question, cites a case of this kind. ''A pair of 
Stone Curlews (Oedicnemus crepitans), affecting almost exclu- • 
sively the most open country," he says,, 'Svere in the habit of re- 
sorting for many years to the same spot, though its character was 
entirely changed. It had been an extensive rabbit warren and 
was become the center of a large and flourishing plantation. It 
seems to me, therefore," he says further, ''that among the causes 
of migration the desire of returning to old haunts must be in- 
cluded" (37). 
But Prof. Newton forgets that any of a vast number of influ- 
ences, which have no direct bearing on the phenomena of migra-: 
tion whatever, may be operating upon the birds to bring them 
back to this same spot. In fact, it would seem in the case he has 
cited, that other forces have been in operation. Old haunts would 
be attractive only on account of their surroundings. If, as he. 
says, these were entirely changed, then, of course, they could no; 
longer be attractive in and of themselves. It is a general belief 
that the sense of memory is well developed in birds ; but, if the 
object of their memory no longer exists, by what shall they rec- 
ognize the place? 
We have found in the preceding discussion that birds are 
quite dependent upon their food supply, and that they are willing 
to undergo the hardships of an unfavorable environment provid-' 
ing their means of existence be assured. Furthermore, we know 
that birds must leave their most favored haunts if the conditions 
become unsuited to their needs of feeding and breeding. In an- 
other connection it will be shown that birds are quite dependent 
upon certain definite courses in their migrations, and that even- 
in the absence of home affection they might be led to the imme- 
36. The Auk, 1890, p. 131. 
37. Newton. Nature, vol. 10, p. 416. 
