• The polar bear, a threatened species in the U.S., dens in coastal tundra."Polar bear" is Copyrighted by Flickr user: mape_s (Marieke IJsendoorn-Kuijpers) under the Creative Commons Attribution license.
  
  

Characteristics

• Tundra habitats are open expanses where climate inhibits tree growth.The cold and a short growing season are major limiting factors. The most extensive form is the arctic tundra of the high latitudes, but there is also alpine tundra, found above the tree-line in high mountains.
  
  

Wildlife

• Despite long, cold winters and limited resources, the arctic tundra attracts large numbers of animals. Only the hardiest remain active and resident year-round; others hibernate or migrate to capitalize on the richest season.
  
  

Migrants

• Many species of birds migrate to the tundra in the summer to rear young. Most of the world's Steller's and spectacled eiders nest in the Northeast Siberian coastal tundra; while rockhopper penguins, southern giant petrels, and other vulnerable species frequent tundra-swathed islands of the Southern Indian Ocean.
  
  

Denning Habitat

• Polar bears, a threatened species in the U.S., utilize tundra adjoining their huge hunting circuits on the sea ice. During the winter on Alaska's North Slope, for example, females often excavate dens in coastal tundra, especially where deep snow has collected.
  
  

Climate Change

• One of the biggest threats to tundra wildlife is the possibility of widespread climate change. Warmer winters may more frequently ice over the pasture of Peary caribou and the dwindling of Arctic sea ice may decrease the hunting efficacy of polar bears, and also make tundra denning habit proportionately more important than offshore options.