6 MICHIGAN BIRD LIFE. 
in the boundary between Canadian and Transition. Other points similarly 
determined would give, when connected, the actual boundary line. In the 
same way theoretically the boundary between Carolinian and Transition 
could be determined. Practically, however, the matter is far from simple. 
It is not easy to decide exactly what species really belong to the Canadian 
or the Carolinian and hence can be used as test species. Birds are less useful 
than mammals or plants for this purpose, since they move so freely and 
rapidly and are so likely to wander or to be carried accidentally far outside 
their proper habitat. And it often happens that a species which in one 
part of the country, say the East, may be perfectly characteristic of a certain 
faunal area will be a very unsafe index a few hundred miles farther west. 
Take for example the species which Dr. Merriam names as characteristic 
of the Carolinian. Among these the sassafras, the fox squirrel and the gnat- 
catcher are found throughout the greater part of the Lower Peninsula, while 
the summer tanager does not occur at all—not even in the southernmost 
counties. On the other hand the porcupine and varying hare, both Canadian 
forms, were found, until very recently at least, in practically every county in 
the state, not infrequently side by side with the opossum and the Cardinal. 
The Carolina Wren, Mockingbird, Yellow-breasted Chat and Tufted Tit 
occur sparingly, perhaps accidentally, over a wide area in the Lower Penin- 
sula, but seem to be nowhere common. 
In the present state of our knowledge, or rather of our ignorance, we hesitate 
to accept Merriam’s faunal map, yet are not prepared to offer a substitute. 
The indications, however, all point toward a decided lessening of the Michigan 
areas assigned by him to the Canadian and Carolinian, with a corresponding 
increase in the size of the Alleghanian or Transition. 
BIRD LIFE IN MICHIGAN. 
In view of the facts just set forth it seems hardly wise to attempt an 
enumeration of the bird species found in each of the faunal areas represented 
in the state. Instead it may be worth while to take a rapid survey of some 
of the different regions of the state with brief lists of the commoner or more 
characteristic species found in each. It must be distinctly understood that 
the mere naming of a species as an inhabitant of any one region does not by 
any means imply that it may not occur elsewhere frequently or regularly. 
It should be noted also that when species are named as common residents 
of any region it is meant as a rule that they are found there during the nesting 
season, that it is in a sense their home. In this connection reference should 
be made to a later page in which the subject of migration is briefly discussed. 
In taking up the matter of bird distribution in Michigan, it will be con- 
venient to consider the bird life of five different regions, namely: 
1. The Prairie Region of the South. 
2. The Great Marsh Regions of the southeastern border. 
3. The Pine Forest Region. 
4. The Plains Region, or “Jack Pine Plains.” 
5. The Hardwood Forest Region. 
The Prairie Region of southern Michigan is really little more than an 
extension northward of the prairies of the adjoining states of Indiana and 
Illinois. Probably it was always devoid of pine forests, at least that has 
been its condition for the last few centuries, and it is now but lightly forested 
at best, and with many large stretches of nearly level land. Characteristic 
