European Souslik (Spermophylus citellus) mouth open, looking alert, Bulgaria

animals souslik eastern european east fields east europe east european vertebrate endotherm mammal developed country ground europe field eastern european nature vertical mammalia zoology sousliks developed countries european citellus verticals ground europe rodent fauna sousliks rodentia bulgaria mammal endothermic wildlife eastern europe bulgarian grasses mouth alert warm blooded warm vertebrates squirrel sciuridae blooded mammals spermophylus animal grass animal