174 WASTE-LAND WANDERINGS. 



tliis time certain portions of Dr. Benjamin Smith Bar- 

 ton's '' Fragments of JN'atural History," published at 

 Philadelphia in 1709, and based upon observations made 

 near that citj. From it we gather evidence that a con- 

 siderable change has been brought about in the habits of 

 certain species, and many that he considered as summer 

 or winter visitors are now strictly resident. It is, of 

 course, possible that the doctor's observations were in- 

 sufficiently extensive, and some birds were overlooked 

 which were really to be found in the vicinity of Phila- 

 delphia at the time ; but this supposition is scarcely ten- 

 able when we consider that Dr. Barton was an intimate 

 friend of William Bartram, and depended largely upon 

 the observations of that accurate observer for his facts. 

 It will be seen, also, that in the ninety-six years since 

 Barton vv-rote, there has been nothing suggestive of a 

 greater regularity in the seasons. March and April were 

 as fickle then as now, and the learned doctor would evi- 

 dently have been sorely puzzled to give an accurate de- 

 scription of spring, of which he has so much to say. 



Speaking of birds coming from the south, at the close 

 of winter. Dr. Barton remarks : " It must not be imasr- 

 ined that the birds which I have enumerated arrive uni- 

 formly every year, at the times which are prefixed to 

 their names. ... I have long been persuaded that the 

 uniformity of the arrival of the migratory birds, in any 

 given country, is not so great as many naturalists have 

 imagined. The attention which I have paid to this cu- 

 rious subject in Pennsylvania has convinced me that my 

 suspicion was well founded. The migration of birds is 

 not a 'determinate instinct,' but an act of volition or 



