VO 'i90? VI ] Trotter, Land-Bird Fauna of N. E. America. 229 



Prince Edward Island list, and it is quite possible that these birds 

 have not vet found their way across Northumberland Strait, while 

 they certainly have invaded the Nova Scotia peninsula, though 

 sparingly, by way of the isthmus. The Red-winged Blackbird 

 and the Meadowlark likewise are not included in Dr. Dwight's 

 list, though recorded by Downs in Nova Scotia as above mentioned. 



These facts, it seems to me, point pretty conclusively to the 

 gradual extension of certain species of birds into an area formerly 

 separated from the main mass of the continent. Nova Scotia 

 offers a singular proof of the use of a land route, for it would seem 

 that birds had found their way into the region by the Amherst 

 isthmus, as evinced by the occurrence of a number of species in 

 localities comparatively near to this district, while still absent, or 

 only occasional, in the more southern and eastern parts of the 

 Province. Most of these species, also, as recorded by Downs, are 

 still comparatively uncommon. In a list of birds observed at Pictou, 

 N. S., from January to July, 1895, by W. A. Hickman, 1 the Chipping 

 Sparrow, Field Sparrow, and Goldfinch are mentioned as very 

 common breeders, but the Catbird, the Bluebird, and the Red- 

 winged Blackbird and Meadowlark are not included in these 

 observations. 



Taking a broad view of the problem it would seem that there 

 is some evidence for entertaining the idea that the extension of 

 species into more northerly breeding grounds is a phase of dis- 

 tribution that is still going on; that our so-called "faunas" — 

 Carolinian, Alleghanian, and Canadian — in reality represent a 

 somewhat temporary state of groups of species in relation to 

 breeding areas, and the more or less arbitrary boundaries of these 

 faunas represent our knowledge only of the present conditions of 

 distribution in a gradual and general northward movement of con- 

 siderable antiquity. Mr. Witmer Stone has furnished me with 

 some interesting facts relating to the northward extension of cer- 

 tain Carolinian birds into the Alleghanian, and even into the 

 Canadian, zones of Pennsylvania. 2 About Harvey's Lake, Lu- 

 zerne Co., and at Lopez, Sullivan Co., since the cutting off of the 

 hemlock timber over considerable areas, the Yellow-breasted 



1 See Ottawa Naturalist, Vol. IX, p. 230. 



2 Stone, 'Birds of Eastern Pennsylvania and New Jersey.' 



