94 
JOURNAL OF MAMMALOGY 
swept clean of snow. Still, broad and level meadows are also favorite 
feeding grounds, especially on windy days. 
When on migration, antelopes may travel a score or more of miles 
in a day. On the plains, in the old days, migration was the regular 
thing and well known to the hunters who frequented the spring and 
fall routes. Even here in the Yellowstone where the total migration is 
limited to thirty miles, three days is enough for these animals to travel 
from the winter range to the extreme limits of the summer habitat. 
The winter range is occupied until the latter part of February, when the 
large bands break up into smaller groups and the individuals show their 
uneasiness by keeping up near the receding snow-line ; and, at the very 
first opportunity in early April, they break through the passes on 
Mount Everts and up the Yellowstone River to the summer ranges to 
the west. The day after they get through, they arrive on the southern 
slopes of the Hellroaring section, and two days later are in the upper 
Lamar Valley. During the migrations, it is a doe that leads the band, 
even though there may be several adult bucks present. But this rule 
is not invariable, for, about once in twenty cases, I find a male leading, 
especially if the band be small. Occasionally a mated pair make the 
migration together, for prong-horns are affectionate and much less 
quarrelsome than others of the large mammals. They remain through- 
out the summer on the higher ranges, and the first return movement 
becomes noticeable about September first when they move down from 
the heights of Specimen Ridge. As a rule the fall migration is a gradual 
one, the prong-horn population moving forward as a whole a mile or 
two a day with many halts, unless an early storm accelerates the 
movement. About the same time that the migration starts at the 
western end, the first migrants appear at the eastern end on the winter 
range. While the migrating prong-horns remain in pairs and small 
groups in September and early October (or the duration of the rutting 
season), they begin to gather in large bands soon after that. During 
October, all the antelopes leave the upper Lamar Valley, Junction 
Valley, and the Hellroaring Range. Some linger a few days on the 
forage ranges about Blacktail Deer Creek, and many stay during 
November on Mount Everts; but usually by December first all are on 
the lower ranges just across the park boundary from Gardiner, Mon- 
tana, extending up the lower slopes of Mount Everts. To be sure 
this schedule is average; weather conditions may retard or accelerate 
the movement considerably at any stage. Even on the winter ranges 
temporary changes of weather cause the prong-horns to move up or down 
