270 



THE OOLOGIST 



Bird Tagging. 

 J. Claire Wood. 

 What wonderful impulse causes the 

 great southward movement of vast 

 multitudes of birds and directs their 

 return in Spring? All attempts to 

 solve this problem will ever remain, 

 in my opinion, just as satisfactory as 

 the origin of species and sources of 

 life. The key to the whole mystery 

 concentrates in the materialization of 

 the properties of instinct. Despite all 

 that has and will be said, the only 

 probable satisfactory explanation is 

 the guidance of that mighty and mys- 

 terious influence that directs the work- 

 ings of all nature. I believe in trans- 

 mutation of species on the data gen- 

 erally accepted as absolute fact of 

 gradation. Though less definite, a 

 consideration of such problems as nat- 

 ural selection, law of design, condi- 

 tions of existance, etc., where they 

 bear in any manner, on migration to- 

 gether with traits I have observed in 

 both birds and mammals (even very 

 young examples of the genus homo) 

 has convinced me that migration is 

 hereditary habit. But I would like to 

 see it proved. To attempt this, in- 

 volves consideration along the lines 

 of contradictory evidence. I frankly 

 confess a confusion of understand- 

 ing, and as a recreation turn to a 

 consideration of the floral and other 

 beauties of summertime in northern 

 climes and look upon migration as a 

 provision of nature that birds should 

 swarm into the scene, and by their 

 beauty, melody and activity, assist in 

 making it a season of delight. Warn- 

 ed, by instinct, of winter's approach, 

 they retreat into the land of perpet- 

 ual warmth, timing their departure 

 according to their constitutional sus- 

 ceptibility to the cold or the first 

 promptings of an inner foreboding. 

 Many, like the Bobolink, abandon an 

 abundance of food to begin the jour- 



ney and never wait until warned by 

 physical contact with cold weather. 

 The Bobolink is southward bound in 

 August and does not reappear until 

 the fruit trees are in blossom. And 

 so strongly is he influenced by the 

 southward impulse that he passes 

 beyond our border, even to the marsh- 

 es of the Rio de la Plata. 



Contemplating the wonderful in na- 

 ture, we fail to understand why an 

 evolutionary tendency has not hard- 

 ened these birds to endure the severity 

 of winter as some species do; but 

 these species are in turn, more or less 

 migratory; being forced southward by 

 extreme cold or failure of food sup- 

 ply. There is nothing remarkable in 

 being driven by a sense of feeling and 

 hunger, but what more impressive of 

 intelligence and design in nature than 

 the early migrants taking an unerr- 

 ing direction to continued warmth and 

 plenty? 



The glacial epoch theory gives no 

 reason whj^ birds should leave warmth 

 and plenty beyond the rather weak ex- 

 planation of seeking the barren waste 

 to rear their young safe from numer- 

 ous tropical enemies, but we know if 

 birds possessed such intelligent sa- 

 gacity they would take advantage of 

 the many southern retreats affording 

 almost absolute security. The ques- 

 tion naturally arises of how they ex- 

 isted before this northern land became 

 accessable, if it is now necessary to 

 them. Thousands perish during these 

 migrations, and it might be asked if 

 the movement is not a natural cause 

 to check increase beyond stipulated 

 bounds; or, on the other hand, to as- 

 sist in keeping down the over-produc- 

 tion of tropical insect and plant life; 

 but all such questions are mere spec- 

 ulation; and of no value except to 

 stimulate discussion. Some endeavor 

 has been made to prove a "law of re- 

 tracement" and again to show that 



