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THE GUIDE TO NATURE 



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SWALLOWS IN MIGRATORY FLOCKS. 



Incidents in Autumn Migration. 

 The mystery of bird migration is 

 -one of the comparatively few yet re- 

 maining in the remarkably developed 

 science of ornithology. It seems pretty 

 well established that in general our 

 migrant birds make their annual 

 spring journeys from a desire, how- 

 ever unconscious or subconscious it 

 may be, for seclusion during the nest- 

 ing period. How do they know there 

 will be seclusion and food and greater 

 safety in the north ? The desire 

 for seclusion is no reason for their 

 flight in the autumn. Their move- 

 ments at this time are most profoundly 

 mysterious than in spring. Many of 

 these migrants are capable of with- 

 standing our severest weather, indi- 

 viduals being found here throughout 

 the winter, yet these species leave in 

 a body while the weather is still fair 

 and their favorite food abundant. Wit- 

 ness a flock of robins on the eve of 

 their departure for the South, frolick- 

 ing in this halcyon weather, feeding to 

 the limit of desire on their favorite 

 wild cherries, mountain ash berries 

 and such fruit. Consider the fact that 

 fully seven out of ten of these birds 

 are the young of the year, and with no 

 knowledge, in any ordinary sense of 

 the word, of other climes. From what 

 to-day would seem to be a bird's para- 

 dise of ease and plenty, they will to- 

 morrow be gone. We know many in- 



teresting secondary facts about this 

 phenomenon, but the problem itself re- 

 mains. 



Migration really begins long before 

 autumn. As early as August I hear 

 the lisping voices of warblers as the 

 first of these birds pass in the early 

 hours of the night. Other species are 

 already gathering in flocks prelimi- 

 nary to leaving. Notable among these 

 are the chimney swifts. These collect 

 every evening about some favored, un- 

 used chimney, and for an hour or so 

 they circle about, passing directly over 

 the chimney at one point ; one or two 

 then fold their wings and drop in out 

 of sight ; the rest follow in ever in- 

 creasing numbers until the last bird 

 finally flutters in. Standing in a room 

 beside such a chimney, I have heard 

 the clamor of two hundred chattering 

 swifts, and the fanning of four hun- 

 dred wings as the birds clung to the 

 bricks. 



Once the migratory flight is begun 

 the birds seems to be guided to a con- 

 siderable extent by certain features of 

 the landscape. Coast lines and river 

 valleys are favored routes. In rainy 

 or cloudy weather the species which 

 fly at night often descend to two hun- 

 dred feet and less from the ground. 

 They are then often attracted and con- 

 fused by any prominent artificial light. 

 Thousands perish by striking against 

 lighthouses and other illuminated 



