Clip | The High Life | The Alps - Annual Alpine Frog Orgy

When the ice on high alpine lakes begins to break, brown frogs appear with a mission. In the hundreds, brown frogs rush to the water, as none want to miss their annual springtime mating ritual.

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(water burbling) - [Narrator] Some like it wet.

An amphibian way above 8,000 feet, sounds like a record.

Brown frogs have spent the winter in underground bodies of water.

On the very day the ice on high alpine lakes begins to break, brown frogs appear as if summoned by a magic reveille.

Marmots are impatient to feed, but not the frogs.

In their hundreds, they race towards the water.

None wants to miss the annual orgy.

In order not to freeze to death, the frogs must move in the daylight.

Their skins have a built in sunscreen.

Ultraviolet radiation at this altitude is powerful.

Just above freezing in here. Quite agreeable.

But in the shallows of a dark peat, the water is lukewarm, the perfect spot to spawn.

(frogs croaking) The males ride piggyback on the larger females, eager to fertilize the spawn as it's released into the water.

The orgy lasts three or four days.

Some males embrace their partners in autumn and cling to them all winter until this super productive spring event.

High mountain populations lay bigger eggs than those in the valleys, giving their offspring a boost for the short alpine summer.