// we take a super-rocket' s-eye view of this continent, we may 

 note that it forms a quite compact unit lying across the 

 hundredth meridian and centered about the point where that line 

 crosses the fortieth parallel on the border of Nebraska and 

 Kansas. By way of analogy we may liken it to a body, with 

 Greenland as its head, Alaska and the Labradorian peninsulas 

 as arms, Baja California and Florida as little hind limbs, and 

 Mexico as a tail. Looked at in this light, and as though it were 

 lying on its back, the South Montane Block would be its stomach, 

 the Rockies and Appalachians its lungs, and the province under 

 discussion here its heart. Indeed, the Great Lakes District and 

 its associated lowlands and subdued southern mountains form 

 the heartland of this continent. 



This province is hard to define although in both 

 phytogeographic and physiographic respects it is clearly 



distinguishable from all the surrounding provinces. Perhaps 

 it is therefore best defined by explaining how it adjoins 

 surrounding areas. 



This continent is shaped like a great V formed of peripheral 

 mountain chains that converge to the south. The area between 

 the arms of the V is filled in with an immense plain, some 

 three thousand feet high at the south and sloping gradually 

 downward to sea level at the Arctic Circle. The only feature 

 that interrupts this formation is the penetration of the bottom 

 of the right-hand arm of the V by the wedge of lowlands or 

 "bottoms" of the Mississippi valley. Somewhat off center, to the 

 east upper side of the central plateau, lies a vast depression 

 filled with the Great Lakes, the largest body of inland waters 

 in the world. 



This province is roughly triangular and is bordered on the 

 north by the Hudsonian, Boreal, or Coniferous Forests — 

 actually, the Pine-Spruce subbelt. Its western face is the limit of 

 closed forest abutting onto the Prairies. Its southeastern edge 

 follows first the eastern face of the Interior Highlands and then, 

 crossing the Mississippi, the western face of the Appalachians. 

 Although it is predominantly a lowland province, two of its four 

 subdivisions are uplands, mounting through foothills to modest 

 mountains. These subprovinces are the Great Lakes, the Central 

 Lowlands, the Western Piedmont of the Appalachians, and 

 the Interior Highlands composed of the Ozark Plateau and the 

 Boston and the Ouachitc Mountains. 



Actually, the major vegetational belts athwart which it 

 lies, extend eastward through the entire Appalachians and to the 

 northwest in a long, narrowing tine to the region of Fort Nelson 

 in British Columbia, by which point they are compressed 

 almost to nothing between the Prairies and the Boreal Forests 

 proper (see general map). The belts are, considered from north 

 to south, the Transition or Mixed Coniferous-Hardwood; 

 the Deciduous, closed-canopy, temperate woodland; and, between 

 this and the Prairie, the Parkland. The dimensions of this 

 province are considerable, its three faces being 1200 miles on 

 the north and west and 1700 on the southeast, giving it un area 

 of no less than 720,000 square miles. 



plied almost prodigiously, spreading far and wide. Yet, in a land 

 that appears to be highly suitable to them both as to climate 

 and food and where predators are no more numerous than in 

 their homelands, and with no natural physical barriers that they 

 could not surmount, these birds spread only just so far and in 

 certain directions. In fact, they spread throughout this province 

 to its east, south, and north borders precisely; only in the west 

 did they march on to cover the whole Prairie Belt north of 

 Oklahoma. Their containment south of the Transition or Mixed 

 Forest subbelt, the southern edge of which cuts across Lakes 

 Michigan and Huron, is remarkable because there is no physical 

 barrier along that line — merely a subtle change in vegetation. 

 The distribution of our indigenous game birds (or galli- 

 naceous fowl) is just as precise. The eastern form of the Wild 

 Turkey (Meleagris gallopavo silvestris), for instance, was once 

 distributed all over the eastern United States from the hundredth 

 meridian to the east coast, except for Florida, where another 

 subspecies (M. g. osceola) held sway. However, it too ranged 

 north exactly to the southern edge of this same Transition Belt. 

 So also did and does the Bobwhite. The Sharp-tailed Grouse, 

 on the other hand, stays north of that line; while the Ruffed 



Grouse, which once covered this province plus Appalachia and 

 all the Boreal Forests to the north of it, has now departed there- 

 from except for a string of isolated "islands" stretching along 

 the Interior Highlands. The Spruce Grouse is even more precise, 

 venturing south precisely to that same line from its Canadian 

 homelands. Here we have no less than five birds of a single 

 group, plus an introduced species, whose ranges are delineated by 

 a "line" or border that is virtually invisible to us. It is one of the 

 most notable demonstrations of the maxim that the distribution 

 of animals is primarily circumscribed by that of vegetational 

 forms. And, just to add a final note of conviction to this maxim, 

 let me add that the Prairie Chicken, which once ranged over the 

 whole Parkland belt, is today confined to just those areas 

 wherein either parkland or prairie conditions have been retained 

 or created by agricultural needs. 



THE AMERICAN BIRD 



I would like to say a few words, in passing, about one of the 

 above-mentioned birds which, in the opinion of not a few, would 



80 



