The blue days of moor frog
A pleasant warmth awakens the moor frog ( Rana arvalis ) from hibernation. The coming spring is luring him out of his winter shelter. He spent the winter hidden in a deep rock crevice, which offered him (overwinter) protection from cold. But this year the shelter was not enough to protect him from freezing. The moor frog (photo: Goran Šafarek). Fortunately for the moor frog, freezing isn’t a serious issue. Though the ice crystals forming in the body can harm cells and organs of most animals, frogs and toads are protected by high concentrations of glucose which prevents the damaging freezing of the tissue. And so, even though his heart stopped beating for a while, at the end of February the moor frog awakes alive and kicking . The male immediately springs into action. His rivals for the females have already started their concert in the nearby pond and there is no time to waste. Their eager singing guides him to the breeding area, which he's been visiting s...