‘ OF NEW ENGLAND. 257 
sion of an introductory paragraph, relative to the Rusty Black- 
birds and their distribution.) 
(c). As is well known, the animals belonging (or indige- 
nous) to a country constitute its fauna. But, in a large country 
like North America, it has been found that different districts 
(bounded by isotheral lines) are inhabited by distinct groups 
of birds, or ornithological faunw. In New England there are 
two faune, the Canadian and Alleghanian, which are chiefly 
separated by the approximate latitude of 44°, or the isotheral 
line of 65°. This line is just to the southward of Mount Des- 
ert and the White Mountains. Most species belong to several 
Saune, but not, as a rule, to merely a part of any one. There 
are several Alleghanian species, however, who have not been 
found, so far as I know, to the northward of Massachusetts. 
On the other hand, several Canadian species have been known 
to breed in this State, chiefly, I believe, along water-courses 
(such as the Nashua Valley), or along mountain-ranges. Birds 
may often be detained or prevented from reaching their usual 
summer-homes, and therefore obliged to remain in a warmer 
climate, especially. in the case of young birds who do not 
breed. Some species ure distributed in an exceptional man- 
ner; thus the Red-bellied Nuthatches are common summer- 
residents in the Canadian district, and breed in the Carolinian 
fauna, but not in southern New England. I have likewise 
observed that the Great Crested Flycatcbers are more common 
among the White Mountains than in Eastern Massachusetts. 
The Long-billed Marsh Wren, moreover, has been found in 
Greenland. During the migrations, especially in autumn, 
birds frequently wander several hundred miles from their usual 
habitat, and, even in summer, may occur to the northward of 
their usual range. Several kinds have even crossed the At- 
lantic, being driven to sea by winds, and afterwards alighting 
on ships. Finally in the list of wanderers are to be included 
escaped cage-birds.87 
The Rusty Blackbirds pass the summer in northern New 
87In the appendix is a list of the species belonging to our two fauna. 
18 
