BORN WITH THE RAIN

 

Deep in the forests of Costa Rica’s Osa Peninsula, during the first heavy rains of the season, groups of hundreds, sometimes

thousands, of gliding tree frogs (Agalychnis spurrelli) descend from the dense canopy and converge on vegetation overhanging freshwater pools, triggering what is known as a “Breeding explosion”.

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The phenomenon lasts only a few hours, during which the frogs form true “amphibian aggregations”: males compete for females and cling to them in amplexus, remaining in position as the females lay their eggs on the leaves, where they are immediately fertilized. When the sun rises high in the sky, the frenzy of the night has long since subsided, and a number of predators take advantage of the exhausted amphibians. Some fall into the water, at the mercy of caimans, while others are easily preyed upon by tiger herons as they make their way back into the canopy.

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The eggs remain suspended from the leaves, exposed to dehydration and to predators. Only a few embryos will survive long enough to complete their development and hatch, plunging into the water below; fewer still will metamorphose and reach adulthood, eventually rejoining the others in the canopy. A unique event, as rare as it is hidden from prying eyes, telling a story of synchronized purpose, a race for survival, and a gamble on life.

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