Habitat
       
 

The yellow-bellied marmot is found in regions of western North America including the US Rockies, Sierra Nevada, and intermountain west. It essentially inhabits subalpine meadows. They are found at altitudes of 2000 meters and up, with a wide range of suitable elevation. This is especially true in the Rockies, where it is common to find them at altitudes approaching 4000 meters or more (Barash 1989). The alpine and subalpine environments they inhabit are characterized by large diurnal fluctuations in temperature. There is intense sunshine in the summer and low temperatures and several months of snow in the winter (Armitage 1991).

The yellow-bellied marmot lives more specifically in a nest site among a pile of boulders. The nest/burrow is worked into the soil found under and between boulders. This burrow system is designed to give the yellow-bellied marmot protection from predators.There are three types of burrows: home, flight and hibernating. However, the same burrow can be used for all three. The yellow-bellied marmot spends approximately 80% of its life in a burrow. The burrow provides protection from the environment, predators, and other marmots. Burrows serve as a hibernaculum in the winter and sometimes act as nurseries in the summer. Thus the selection of the burrow site is very important. Most burrows have the same general configuration. They are typically found on open-grassy or herb covered slopes facing northeast or southwest and contain rocks or boulders. The rocks support the burrow and provide the marmot with sunning and observation sites. Burrows are often not used extensively. Marmots often switch burrows between seasons and females often move their young to a new burrow after birth. There is often a burrow plug during the hibernaculum that is composed of fecal matter and dry grass. This plug reduces circulation and keeps out small predators (Svendsen 1976).

 
           
           

Distribution map of the yellow-bellied marmot. (Smith 2001) with permission.

         
                                 
       

Burrow entrance. Photo courtesty of Dennis Deck.

 
Rocky outcrop habitat. Photo courtesy of Dennis Deck    
 
The yellow-bellied marmot is a generalist herbivore. It feeds primarily on seeds, flowers, leaves, and stems of a wide variety of grasses, forbs, and shrubs. They forage during the day on vegetation either on the rocks or in the meadow just off their rocky outcrop habitat. Plant food chosen by the yellow-bellied marmot is based on relative abundance, nutritional quality and energy requirements. Diet choice and the amount of food that the marmot intakes is very important because the marmot must acquire enough fat storage to last them throughout their hibernation period. Marmots do change physiologically in late active season, prior to hibernation. Their metabolism slows, most likely to divert excess energy into fat reserves (Edwards 1997). The water content of plants could be critical for maintaining water balance in the marmot. Food selectivity of the yellow-bellied marmot is affected by the phenology of plant species and avoidance/low intake of plant secondary compounds. Marmots try to maximize their total energy intake while meeting specific nutrient requirements (Frase 1989).  
                             
                   
        Valerian, a common food source. Photo courtesy of Dennis Deck
         
                   
   

Predators: Eagles, badgers, grizzly bears, coyotes, weasels, martens, and mountain lions.

Predation is definately a threat to the yellow-bellied marmot, but the threat of hibernation has been found to be greater in some cases. The severity of winter leads to greater mortality during hibernation. Winter also affects reproduction in the female yellow-bellied marmot. There are generally more young per female and more litters when winters are shorter (Armitage 1974).

Predator Defense: alarm calls and the nest and burrow system. Marmots utilize the run and hide method when they come into contact with a predator.

 
                   
        Return to Home