Emerging from a partially frozen pond more than 6,000 feet high in the Alps, European common frogs (Rana temporaria) set out to find mates and begin breeding activities.
The search for mates often begins underwater, before surface ice has melted. Photographer Cyril Ruoso could hear the calls of male snow frogs in spring even through the ice of Alpine ponds.
Snow frogs mate (katak salju kawin) in a position called amplexus, with the smaller male frog clasping the female from behind in a ride that can last two days or more. As she lays eggs, he expels sperm to fertilize them.
Snow Frog pairs can begin hibernation in amplexus, turning it into a months-long embrace that may provide a breeding advantage by allowing mating as quickly as possible once warm weather arrives.
Eggs of high-elevation frogs may be 30 percent larger than those of lowland females, giving tadpoles a head start.