European Souslik (Spermophylus citellus) peering out from burrow, Bulgaria

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