PART III — CLIMATIC CHANCE 



horses, and bison at the time of their 

 extinction 11,000 years ago was not 

 vastly different from what we know 

 at present. Why, then, did the ani- 

 mals die? Fossil pollen and other 

 evidence from the radiocarbon dating 

 of extinct Pleistocene faunas seem to 

 indicate that no environmental defects 

 will explain this phenomenon. One 

 must look elsewhere. And the only 

 new variable in the American ecosys- 

 tem of the late-glacial period is the 

 arrival of skilled Stone Age hunters. 

 These events of thousands of years 

 ago have major implications for mod- 

 ern-day range management. 



Implications for Modern Range 

 Management 



In part, the concept of the West as 

 a "desert" is based on the fact that 

 grass production is indeed quite low. 

 But the dominant woody plants found 

 across the one million square miles of 

 western America — the creosote bush, 

 sagebrush, cactus, and mesquite — do 

 yield large amounts of plant dry- 

 matter annually. Primary productiv- 

 ity data on these western shrub com- 

 munities are less abundant than one 

 might wish. Nevertheless, such data 

 as do exist indicate that shrub com- 

 munities in southern Arizona may 

 yield 1,400 kilograms per hectare a 

 year, considerably more than adjacent 

 grassland under the same climate (12 

 inches of precipitation annually). 



Observers have overlooked or writ- 

 ten off this annual production, per- 

 haps because it is often avoided by 

 domestic livestock. Indeed, fifty years 

 of range management in the West has 

 been aimed at destroying the woody 

 plants to make way for forage more 

 palatable to cattle. The effort has 

 been singularly futile and should be 

 abandoned. 



The Future of Western Meat-Pro- 

 duction — The dilemma faced by the 

 range industry in arid America is that 

 beef can be produced faster, more 

 efficiently, and at less expense in the 

 southeast or in feedlots. If this fact 

 is accepted, one can make a case for 

 keeping large areas of arid America 

 as they are, at least until much more 

 is known about primary production of 

 the natural communities and until 

 some value for Western scenery can 

 be agreed upon. Some large, wealthy 

 ranchers have already recognized this 

 and have disposed of their cattle. 

 More should be encouraged to do so. 

 If a meat-producing industry is to be 

 established in the marginal cattle 

 lands in the West, it should be based 

 on new domestic species, animals that 

 are better adapted to arid environ- 

 ments than cattle and that are adapted 

 for efficient browsing rather than 

 grazing. 



Potential New Domesticates — One 

 obvious source for potential new 



domesticates is Africa, where arid 

 ranges that barely sustain cattle are 

 supporting thrifty herds of wilde- 

 beest, kongoni, zebra, giraffe, and 

 kudu. In size and general ecology, the 

 African species bear at least general 

 resemblance to the extinct Pleistocene 

 fauna of the Americas. They did not 

 invade the New World during the ice 

 ages because they failed to range far 

 enough north to be able to cross 

 the Bering Bridge, the only natural 

 method of intercontinental exchange 

 open to large herbivores. Many natu- 

 ral faunal exchanges of arctic-adapted 

 herbivores did occur over the Bering 

 Bridge in the Pleistocene. Some, but 

 not all, of the invaders re-adapted to 

 warmer climates of the lower latitudes. 



In summary: (a) Studies of fossil 

 pollen and other evidence of the last 

 30,000 years reveal no environmental 

 defects that might explain the extinc- 

 tion of many species of native New 

 World large mammals 11,000 years 

 ago. (b) The only known environ- 

 mental upset at the time of large ani- 

 mal extinction was the arrival of Early 

 Man. (c) The cattle industry of west- 

 ern America is marginal, being main- 

 tained for reasons of its mystique, not 

 for its economics, (d) If a more pro- 

 ductive use of the western range is 

 desirable, experiments with other 

 species of large mammals should be 

 begun now, as indeed they have been 

 on certain ranches in Texas, New 

 Mexico, Mexico, and Brazil. 



74 



