Relationships between group size, feeding time, and agonistic behavior of mountain goats
Relationships between group size, intragroup spacing, movement rates, foraging behavior, and frequency of agonistic behavior of mountain goats (Oreamnos americanus) using alpine tundra were examined during summer. Feeding time of goats increased with group size to about 12 goats because of a reduction in time devoted to alert behavior. Rates of movement by foraging goats increased with group size, whereas rates of agonistic behavior between goats declined with increased group size. Intragroup spacing declined as group size increased. Nannies and 2-year-old goats were more aggressive than were other sex- or age-classes. Two-year-old goats, yearlings, and billies received more threatening displays than did other classes. In Colorado, nannies with kids form large nursery bands on alpine tundra. This behavior can reduce the risk of predation to individuals while allowing nannies with kids to exploit forage away from precipitous terrain. Average group size may be a useful index to forage abundance and continuity on summer goat range.