XII 



The migrants' cry Unrest previous to departure Upland plover, 

 swallows and others Demonstrative and undemonstrative 

 species Parental solicitude Swifts and house-martins 

 Strange case of a captive cuckoo Night migration of diurnal 

 species Woodland migrants on the pampas Reluctant 

 migrants Thistledown as an illustration Migration of a 

 troupial Fear in birds and false associations Direction of 

 migration Unrest Flying north Migration of rock-swal- 

 low Pull of the north Perturbations in migration 

 Upland plover. 



WHEN in my boyhood I listened day and 

 night to that cry of the upland plover, 

 it came to me that the explanation of the 

 passage birds' cry given in the books could not be 

 true, or not true in all cases. Birds, it was said, 

 emitted these calls as a sort of watchword, and to 

 prevent their followers from scattering. Certainly 

 it was not true of the upland plover, seeing that it 

 travelled alone day and night. Moreover, the sound 

 was not a call but a cry of alarm the cry invariably 

 uttered by the bird, when flushed by man or dog, 

 as it rushed wildly away through the air. 



I then made the further discovery that this same 

 cry of alarm was frequently uttered by the bird, 

 without visible or audible cause, on the eve of migra- 

 tion, or rather for some days previous to departure. 

 The time varied every year, from two or three or 

 four to ten or twelve days ; the cry and action always 



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