Characteristic for the alpine zone of palearctic mountains is a short vegetation period. For many months each year snow cover inhibits the growth of plants. Additional factors like low oxygene and carbon dioxide pressure complicate the growth of plants. Herbivore animals, therefore, must have developed adaptations to endure periods of food shortage. Food shortage can also be a problem in alpine zones of the tropics, but there, the reduced plant growth results from drought and not from cold and snow cover.

One way to avoid food shortage is by migration to habitats with a richer food supply. Red deer (Cervus elaphus) for example find enough food in the montane forests. Migration demands a high mobility and can therefore be seen mainly among large herbivores.

1 - Red deer (Cervus elaphus) make seasonal migrations. (Photo: M. Merker; 91K)

2 - Mountain pygmy possum (Burramys parvus), a hibernating marsupial from the Snowy Mountains of Australia (Photo: K. Green; 109K)

To overcome periods with food shortage, the marmot (Marmota marmota) in the European Alps and the mountain pygmy possum (Burramys parvus) in the Snowy Mountains hibernate. The metabolism is lowered to a minimum so that very little energy is needed and the animal can live on fat reserves for several months without new food intake.

Current research has shown that some animals can reduce organs to save energy consumption. The small intestine in marmots (Marmota marmota) has been shown to increase by approxymately 1 m and 260% of fresh tissue weight after emerging from hibernation in spring. Other parts of the gastrointestinal tract as well as myotic activity show a similar increase in spring. From midsummer (July) till September the first parts of the digestive system already begin to decrease in size and mass. However, organs continue to work at a lower level throughout hibernation. The growth in spring is a response to ingested food rather than to an endogenous signal.

The strategy of saving energy through organ reduction is also assumed by deer (Cervus elaphus, Capreolus capreolus) and ibex (Capra ibex).

Chamois (Rupicapra rupicapra) and Ibex (Capra ibex) reduce their activity to save energy.
 

3 - Disturbance by winter tourism can endanger the survival of wildlife. (137K)

Hoarding food as is known in squirrels (Sciurus spp.) at lower altitudes is very rare in alpine animals. An exception is the nutcracker (Nucifraga caryocatactes) who collects hazel- and pine nuts and whose food supply is so abundant that nutcrackers can even breed in winter. By not always finding all the nuts it burys, the nutcracker contributes to the spread of trees and helps to form the upper timberline. Sporadically, the hoarding of crocus bulbs can be observed in the common vole (Microtus arvalis).

4 - Nutcracker (Nucifraga caryocatactes) and its food stock

Hume ID et al (2002) Seasonal changes in morphology and function of the gastrointestinal tract of free-living alpine marmots (Marmota marmota). J Comp Physiol B 172(3):197-207.

29 August 2011
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