Response to Development and Effects on Other Wildlife  
  
 
 
 
 
  
 
 

Mammals of the North Slope  
Several species of mammals also inhabit the Slope; lacking wings, these are year-round residents.  Caribou exhibit smaller-scale migration patterns within the region, moving south to the foothills in the winter, and north in the summer to take advantage of the growing plants and the reduced insect density (most days!) near the coast.

Male caribou at Prudhoe Bay in July

Female caribou with calf
Musk oxen, whose hair is the best-insulating fiber in the animal kingdom, hardly seem affected by the cold and snow; they live in the same areas throughout the year, digging holes through the snow to reach grass to eat during the winter.  Musk oxen were hunted to extinction in Alaska, but herds were brought from Siberia to reestablish the species here. One herd is doing well near Prudhoe Bay.

 

Brown bears (grizzlies) respond to the seasonal food availability by hibernating through the winter, after eating plenty of lemmings, eggs, caribou, musk oxen, and berries all summer. 
Polar bears are marine mammals, totally at home in the water and dependent on sea ice for their survival. When the sea ice is far offshore, they sometimes swim to land to rest. If necessary, they will hunt birds or small mammals on land; but their preferred prey are seals, and they will return to the ice as soon as they can. Pregnant females hibernate through the winter, giving birth to their cubs then; but others are active year-round.



Throughout the summer, foxes store food in caches, which they then dig up over the winter when food is in short supply.  Eggs are especially good items to cache, as they are easily transported and store well inside the shell—as long as you don’t mind that rotten taste when you dig it back up! 

Red Fox
Arctic Fox, still mostly in winter coat, carrying a goose egg

 

 Arctic ground squirrels, which live in scattered colonies where the permafrost lies deep enough to allow them to dig burrows, hibernate through the winter and live on an omnivorous diet through the summer. 

 

Lemmings are active year-round, tunneling under the snow in winter, where they are insulated from the cold and can access plants to eat; their populations fluctuate in three- to six-year cycles in our study region.  Particularly during years in which they are most abundant, lemmings are the most important food source for many North Slope predators. Below left is a Brown Lemming, the most common rodent in our study area; right is a Collared Lemming.

 

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All photos copyright Emily Weiser. Please request permission for anything other than personal use.