Musk-ox underlay fur - also known as 'quivat' - is one of the warmest natural substances on earth, with 3 1/2 times the insulation value of goose down. At the turn of the century, this value led to musk-oxen being slaughtered to near extinction along Canada's and Alaska's Arctic coastal areas - mostly by European whaling ships. Only the musk-oxen that were less accessible to these hunting forays such as those residing on the higher Arctic Islands and in the deep mainland interior continued to survive. For this reason, and encouraged by the advice of explorer's David Hanbury, J.W. Tyrell, John Hornby & Critchell Bullock, a order in Canadian Council led to the establishment of the Thelon Wildlife Sanctuary in 1926 to protect Canada's remaining musk-oxen against further demise. Since then, the herds of the Thelon country have flourished, now spilling out into adjacent regions in recent years. This photo was taken by and donated to this site by the late Bill Silliker, Jr. from a 1998 Great Canadian Wilderness 'Dance with Caribou' expedition to the upper Thelon region of the NWT.