Mountain Wildlife - Mountain Geography: Physical and Human Dimensions - page 420

the next. Carabid beetles in the western Himalaya were found hibernating as adults one
year and as larvae the next (Mani 1962). A similar situation exists among the moths,
flies, and spiders. On the other hand, high-altitude flies and mosquitoes complete their
development in one season (Smith 1966). The exact behavior depends on the insect
type and environmental conditions, but since the growing season becomes progressively
shorter at higher altitudes, overwintering in intermediate forms becomes increasingly
characteristic (Fig. 8.2).
Insects hibernate by shallow burrowing or by crawling under rocks and into crevices.
Snowfall must be adequate to cover the hibernation site during winter. Since the tem-
perature under the snow remains fairly constantly at or near freezing (Fig. 8.6), hibern-
ating insects need not endure extreme and fluctuating air temperatures. Insects usually
do not emerge from hibernation in summer until the snow has melted. Thus, patterns
of emergence depend on local conditions more than on altitude. Similarly, because hi-
bernation is prolonged, development must be very rapid once conditions permit, in or-
der for the insect to complete its life cycle or at least a segment of it. Since conditions
are highly variable from year to year and from place to place, organisms must main-
tain considerable flexibility in the timing of their activities. Nature is not very precise
or predictable in mountain environments; variability is the rule rather than the excep-
tion. Many animal forms show a kind of opportunism in their capacity to take advant-
age of favorable conditions when they appear and, equally, are able to withstand and
persist through unfavorable periods (Downes 1964). For example, many high-altitude
insects have the ability to begin hibernation at almost any stage of development and to
remain dormant for prolonged periods. A case in point is seen when an avalanche traps
insects under the snow for several years: They are usually not killed, but simply remain
dormant until the snow melts and they are freed (Mani 1962).
Reptiles and amphibians do not generally inhabit the highest elevations, but some do
range into the lower alpine zone (Hesse et al. 1951; Pearson 1954; Swan 1952, 1967;
Karlstrom 1962; Campbell 1970; Bury 1973; Pearson and Bradford 1976). Being cold-
blooded, their internal temperature is dependent upon the surrounding environment.
They are largely limited to periods of activity when the sun is shining, and there is
simply not enough heat or food during winter to maintain activity. Hibernation in cold-
blooded animals is very different from that in warm-blooded animals. The latter exper-
ience a profound and controlled drop in internal temperature, but in cold-blooded an-
imals it is difficult to detect any physiological difference between hibernating and non-
hibernating individuals. Nevertheless, apparently, the heart rate and blood pressure do
drop, and other subtle metabolic changes occur (Aleksiuk 1976).
In preparation for hibernation, snakes and lizards crawl under rocks or into animal
burrows. They have a tendency to gather in groups, and it is not uncommon to find a
variety of life forms, including insects, all congregated under one rock. This leads to
very mixed bedfellows, with predator and prey gathering under the same roof, snuggled
together for the duration (Fig. 8.7).