368 EXTINCT AND VANISHING MAMMALS 



where the bighorns doubtless cross freely from one mountain 

 range to another." The authors quoted state that "probably 

 not more than 25 mountain sheep occur in all the Guadalupes, 

 none of them on the top in the heavily wooded sections." 

 The numbers here seem to be decreasing but were probably 

 never very high. In other ranges single rams or rarely small 

 bands appear sporadically from time to time, but in other of 

 the 16 mountain masses for which data were gathered sheep 

 have been absent for years. Perhaps not more than 30 occur 

 south of the Texas and Pacific Railway. Summarizing the 

 figures given, there are approximately 410 bighorns in western 

 Texas, of which some 300 are found in the four mountain 

 ranges Baylor, Beach, Carrizo, and Sierra Diablo, while the 

 remainder are chiefly in the Apache (40), Guadalupe (25), 

 Delaware (17), Eagle (8), and Glass (13) Mountains. The 

 requirements of these sheep include not only craggy regions 

 but also a particular type of vegetation, of low, shrubby, 

 xerophytic sorts, low enough to afford an unobstructed view. 

 In the Baylor Mountains the evidence seems to show that 

 bighorns move into them seasonally and leave "when condi- 

 tions are adverse." Young are born in March and April, 

 usually a single one at a time, and they follow their mothers 

 throughout at least the first summer and autumn. Davis 

 found that in the Yellowstone National Park grass constituted 

 nearly 60 percent of the food for Rocky Mountain bighorns, 

 but for the Texas bighorns investigation shows that grass con- 

 tributes about 3 percent only, and that the animals prefer 

 mountain-mahogany, Mexican tea, yellow trumpetflower, 

 mock-orange, and wild onion. Davis and Taylor consider 

 carefully the reasons for the decrease in numbers of this big- 

 horn and conclude that it is not due to overhunting, for the 

 season has been closed since 1903; nor is it a result of depre- 

 dations by mountain lions, for these predators have been re- 

 duced to very small numbers. Golden eagles may take toll of 

 a few lambs, but these birds are not a very significant factor, 

 and besides predators have always lived in the region. They 

 conclude that "the incursion of domestic sheep possibly has 

 been the most serious factor affecting bighorn numbers" and 

 suggest that this is in part because of the introduction of 

 diseases to which domestic sheep are liable, in part to direct 

 competition for food and water, and in part perhaps to an 



