The snowy owl is mostly white. They are purer white than predatory mammals like polar bears (Ursus maritimus) and Arctic fox (Vulpes lagopus). Often when seen in the field, these owls can resemble a pale rock or a lump of snow on the ground. It usually appears to lack ear tufts but very short (and probably vestigial) tufts can be erected in some situations, perhaps most frequently by the female when she is sitting on the nest.