CJROLfXfAX A]' I FAUX A 83 



lines between these faunas cannot, of course, be sharply drawn. 

 The change from one to another is gradual, and between the two 

 a neutral strip exists in which will be found species characteristic 

 of each. Just such a condition is found in this vicinity, the north- 

 ern boundary of the Carolinian Fauna over-lapping the southern 

 boundary of the Alleghanian Fauna in the valleys of the Delaware, 

 Hudson and Connecticut. In other words, we have here on the 

 one hand a number of birds which are found no farther north 

 and on the other certain species which are found no farther south ; 

 that is, in the breeding season, for among birds only the nesting 

 ranges are of value in determining the boundaries of faunas. 



The southern limit of the Carolinian Fauna on the Atlantic 

 Coast is near Norfolk, A'irginia ; its northern limit, on the coast, 

 as said above, is in the vicinity of New York City. To be more 

 exact, a careful study of the nesting ranges of certain species 

 shows that the most northern points at which they are regularly 

 found is Port Jervis in the Delaware valley, Fishkill in the Hud- 

 son River valley, and Portland in the Connecticut River vallev. 

 These localities then may be considered as defining the northern 

 limits of the Carolinian Fauna in the valleys in which they are 

 placed. In the more elevated country between these points it 

 is doubtful if the limits of the fauna reach quite as far north, for 

 river valleys, both because they offer a natural pathwav for the 

 extension of a bird's range, and because of the higher tempera- 

 ture prevailing in them, tend to carry northward the boundaries 

 of faunas. Eastward, along the Connecticut shore, the Carolinian 

 Fauna may reach the mouth of the Thames. Long Island, although 

 farther south, belongs for the most part in the .\lleghanian rather 

 than the Carolinian Fauna. Numbers of species common and 

 even abundant in the Lower Hudson valley are exceedingly rare 

 on Long Island, especially on the southern shore. But along the 

 northern shore, or older part of the island, where deciduous trees 

 abound, there is an evident trace of the Carolinian Fauna shown 

 bv the regular occurrence of the Blue-winged \\'arbler and the 

 Acadian Flycatcher. 



The following Carolinian birds are found every summer 

 within 50 miles of the ^Museum, and all but two or three are known 

 to nest regularly here. Their occurrence as breeding birds north- 

 ward beyond these limits is, with but few exceptions, rare and 

 irregular. 



[5] 



