40 PROCEEDINGS MANCHESTER INSTITUTE 



these birds inhabiting the new growth of bushes and vines far " 

 in the forest, sometimes within a year or so after the clearing of 

 a patch of heavy timber. The complete change of the cleared 

 territory within a short time, from a dense, damp spruce forest 

 inhabited by a northern fauna, to a dry, sunny, and sheltered 

 area of deciduous bushes and vines, leaves it for a time almost 

 unoccupied, but the keen competition for the available territory 

 of support must soon force the discovery of the new region by 

 those organisms fitted to inhabit it. Thus it is that some birds 

 already living close at hand, such as the Canadian Ruffed 

 Grouse, White-throated Sparrow, Slate-colored Junco, Mag- 

 nolia and Black-throated Blue Warblers, are quick to spread 

 into a forest clearing, while a more southern species, such as 

 the Chestnut-sided Warbler, must take much longer to discover 

 the spot and settle there in any numbers. Among the White 

 Mountain valleys, we sometimes see in the same grove, this 

 meeting of northern and southern species. Thus in the Saco 

 valley at Intervale, in a large and rather open sugar-maple 

 grove, I have found such species as the Screech Owl and the 

 Wood Thrush summering with the Mourning Warbler and the 

 Hermit Thrush. Here, evidently, is not a condition of stable 

 equilibrium. In some years, I have missed the Mourning 

 Warblers from the grove altogether, while again I have found 

 three pairs in an area so small that the males of aH three might 

 be in hearing at one time. The Wood Thrush appeared for two 

 years (1899 and 1900), but a hasty search in early summer of 

 the third year failed to reveal it again. 



Of the Transition avifauna, we may distinguish a number of 

 birds whose breeding area lies largely to the south, but extends 

 northward into this zone in New Hampshire. Of these birds, 

 certain ones are more or less common throughout the area, 

 breeding well up into the valleys of the White Mountains. 

 Such are : Screech Owl (Megascops asio), Whip-poor-will (An- 

 trostomus vociferus} , Nighthawk (Chordciles virginianus) , King- 

 bird (Tyrannus tyrannus), Crested Flycatcher (Myiarchus cri- 

 nitus), Phoebe {Sayornis phcebe), L,east Flycatcher (Empidonax 

 minimus}, Red- winged Blackbird {Agelaius phceniceus}, Balti- 



