OF THE LARGE AMERICAN MAMMALS 221 
in the Jackson Valley, particularly a tract known as “‘the 
swamp,” and others on the surrounding foot-hills where the 
herds annually go to graze in winter. A measure to render 
this possible was presented to Congress in the winter of 1912, 
and without opposition an appropriation of $45,000 was made. 
The photographs of the elk herds that recently have been 
made by 8. N. Leek, of Jackson Hole, clearly reveal the fact 
that the herds now consist chiefly of cows, calves, yearlings 
and young bulls with small antlers. In one photograph (see 
page 67) showing about 2,500 elk, there are not visible 
even half a dozen pairs of antlers that belong to adult bulls. 
There should be a hundred! This condition means that the 
best bulls, with the finest heads, are constantly being selected 
and killed by sportsmen and others who want their heads; 
and the young, immature bulls are left to do the breeding 
that alone will sustain the species. 
It is a well-known principle in stock-breeding that sires 
should be fully adult, of maximum strength, and in the prime 
of life. No stock-breeder in his senses ever thinks of breed- 
ing from a youthful, immature sire. The result would be 
weak offspring, not up to the standard. 
This inexorable law of inheritance and transmission is 
just as much a law for the elk, moose and deer of North 
America as it is for domestic cattle and horses. If the pres- 
ent conditions in the Wyoming elk herds continue to prevail 
for several generations, as sure as time goes on we shall see a 
marked deterioration in the size and antlers of the elk. 
It is impossible to maintain any large-mammal species 
at its zenith of size, strength and virility by continuous breed- 
