Mountain Wildlife - Mountain Geography: Physical and Human Dimensions - page 430

than earlier ones. This is particularly marked at higher altitudes and around the mar-
gins of melting snow. Even though development during the summer is fast, the season
is frequently so short that the insect must overwinter at intermediate stages of its life
cycle, taking two or three years for complete maturation (Mani 1962). Like other anim-
als, insects display a tendency to become single brooded at greater heights. A species
that is double brooded at lower elevations may become single brooded at higher eleva-
tions. This is expressed differently in various insects, but the adaptive strategy is sim-
ilar (Fig. 8.2a-c). A few insects, such as the Diptera (mosquitoes, flies), can reproduce
several times in spite of the brevity of the growing season (Fig. 8.2d). The ability to do
this is one reason for their abundance in high-altitude and high-latitude environments
compared to such species as butterflies, which take two or more seasons to complete a
single generation.
Morphological and Physiological Adaptations
The fundamental ingredients for survival are the ability to escape predation, to with-
stand climatic extremes, and to find the best food, summer or winter. This is achieved
through behavioral, physiological, and morphological adaptations.
Antipredator Strategies
Security is the first priority in life; food is secondary. In the face of diverse predators,
large prey species evolve sophisticated antipredator adaptations. On predator-free is-
lands, large herbivores dwarf, their antipredator adaptations degenerate, but their feed-
ing organs specialize to deal with the increasingly impoverished food supply brought
on by crowding and competition. In mountains, steep slopes and cliffs offer excellent
opportunities for large herbivores to thwart terrestrial and aerial predators. Sophistic-
ated climbing and rock-jumping evolve to evade predators, but also to counter attacks
and fling predators from cliffs or to cripple attacking aerial predators. Small-bodied
mammals invariably seek safety below ground, while birds living above ground evolve
sophisticated camouflage patterns. All prey species evolve excellent senses to detect
approaching danger.
Where much snow and ice prevails, jumping is counterproductive as the cliff surfaces
are largely hidden from view by snow. Here sophisticated climbing adaptations, such
as those of the American mountain goat, may evolve. Cliff hoppers such as ibex ( Capra
ibex ) or mountain sheep require excellent binocular vision, as well as excellent night
vision to navigate in cliffs day or night. As expected, they have large, well-spaced eyes.
The mountain goat, a climber, does not. It operates effectively over shorter distances.
It has very muscular appendages with effective leverage systems, terminating in large,
padded hooves to provide traction. Mountain goats avoid climbing about at night and
seek out the safety of cliffs before nightfall. Mountain sheep appear to be good at noc-
turnal navigation, one reason they live in mountains well above the Arctic Circle, where
mountain goats do not (Geist 1971). Year-round observations and radiotelemetry have
greatly advanced our knowledge of this mountain dweller (Chadwick 1977, Festa-Bi-
anchet and Cote 2008).