▁protect ▁the ▁eyes ▁while ▁under water , ▁as ▁well ▁as ▁a ▁' mask ' ▁which ▁covers ▁the ▁eyes ▁and ▁e ard rum s . ▁Although ▁the ▁common ▁f rog ▁has ▁long ▁h ind ▁legs ▁compared ▁to ▁the ▁common ▁to ad , ▁they ▁are ▁shorter ▁than ▁those ▁of ▁the ▁ag ile ▁f rog ▁with ▁which ▁it ▁shares ▁some ▁of ▁its ▁range . ▁The ▁longer ▁h ind ▁legs ▁and ▁f ain ter ▁colour ation ▁of ▁the ▁ag ile ▁f rog ▁are ▁the ▁main ▁features ▁that ▁distinguish ▁the ▁two ▁species . ▁ ▁M ales ▁are ▁distinguish able ▁from ▁females ▁as ▁they ▁are ▁smaller ▁and ▁have ▁hard ▁sw ell ings , ▁known ▁as ▁nu pt ial ▁p ads , ▁on ▁the ▁first ▁digits ▁of ▁the ▁fore leg s , ▁used ▁for ▁g ri pping ▁females ▁during ▁m ating . ▁During ▁the ▁m ating ▁season ▁males ' ▁thro ats ▁often ▁turn ▁white , ▁and ▁their ▁overall ▁colour ▁is ▁generally ▁light ▁and ▁grey ish , ▁whereas ▁the ▁female ▁is ▁brow ner , ▁or ▁even ▁red . ▁ ▁Distribution ▁ ▁The ▁common ▁f rog ▁is ▁found ▁throughout ▁much ▁of ▁Europe ▁as ▁far ▁north ▁as ▁northern ▁Sc and in avia ▁inside ▁the ▁Ar ctic ▁Circle ▁and ▁as ▁far ▁east ▁as ▁the ▁Ur als , ▁except ▁for ▁most ▁of ▁I ber ia , ▁southern ▁Italy , ▁and ▁the ▁southern ▁B alk ans . ▁Other ▁areas ▁where ▁the ▁common ▁f rog ▁has ▁been ▁introduced ▁include ▁the ▁Is le ▁of ▁Lewis , ▁Sh et land , ▁Or k ney ▁and ▁the ▁Far oe ▁Islands