frog calling in water. one breeding male pool frog crying with vocal sacs on both sides of mouth. pelophylax lessonae

frog calling water amphibian pool crying pelophylax lessonae vocal sac male breeding swimming plant wildlife biodiversity croaking marsh animal outdoors one nature vegetation environment wild common ecology aquatic brown closeup spring summer green esculenta esculentus lake loud call pond river swamp switzerland day behavior true grass sound reflection reserve conservation