Spawning season

Common frogs indicate that spring is around the corner

GLIMPSING THE BULGING GELATINOUS MOUNDS IN THE SHALLOWS BRINGS OUT THE INNER CHILD IN US.”

F reshly laid frogspawn has an uncanny ability to lift our spirits on the chilliest of February and March days. But not only is frogspawn a sign that spring is just around the corner, it’s also extraordinary in itself. A protein that draws water into the egg mass is the secret that enables animals just 9cm long to produce such copious volumes of jelly. A large female frog may deposit as many as 2,000 eggs – no wonder these amphibians have long been associated with fecundity – and the spawnings of different individuals clump together in wobbling rafts.

Unseasonally late freezing weather can spell disaster for exposed frogspawn at or above the water level – killing it off and turning it milky – though underwater eggs at the bottom of the floating clumps usually survive. Hungry mallards and moorhens are another threat, often feasting at night, while some spawn isn’t viable and quickly dies. Remaining spawn hatches in around two to three weeks, and the tadpoles embark on a metamorphosis lasting four to five months. It has been estimated that only one in 50 eggs eventually becomes an adult common frog –a tiny proportion, but sufficient to sustain the species.