 Investigation in Yellowstone National Park showed that elk , followed by mule deer , were the cougar 's primary targets ; the prey base is shared with the park 's gray wolves , with which the cougar competes for resources . Another study on winter kills ( November – April ) in Alberta showed that ungulates accounted for greater than 99 % of the cougar diet . Learned , individual prey recognition was observed , as some cougars rarely killed bighorn sheep , while others relied heavily on the species . 
 Investigation in Yellowstone National Park showed that elk , followed by mule deer , <a href='uninflect' title='1'><mark>were</mark></a> the cougar <a href='null_genetive' title='2'><mark>'s</mark></a>primary targets ; the prey base is shared with the park <a href='null_genetive' title='3'><mark>'s</mark></a>gray wolves , with which the cougar <a href='uninflect' title='4'><mark>competes</mark></a> for resources . Another study on winter kills ( November – April ) in Alberta showed that ungulates accounted for greater than 99 % of the cougar diet . Learned , individual prey recognition was observed , as some cougars rarely killed bighorn sheep , while others relied heavily on the species . 
Investigation in Yellowstone National Park showed that elk , followed by mule deer , was the cougar  primary targets ; the prey base is shared with da park  gray wolves , wid which the cougar compete fa resources . Another study on winter kills ( November – April ) in Alberta showed dat ungulates accounted ffirgreater than 99 % of the cougar diet . Learned , individual prey recognition was observed , as sum cougars rarely killed bighorn sheep , while others relied heavily on the species .