Saturday 29 April 2017

'Great slime kings' gather in turmoil

Springwatch: A common frog awaits a mate at a pond in Co Meath. Photo submitted by reader Paul Johnston
Springwatch: A common frog awaits a mate at a pond in Co Meath. Photo submitted by reader Paul Johnston

Joe Kennedy

At the festering flax-dam, the boy Seamus Heaney filled jam-potfuls of jellied specs of frogspawn "that grew like clotted water".

These went to window-sills at home and school until the fattening dots burst into nimble-swimming tadpoles.

But finding how that came about, when the air was "thick with a bass chorus and gross-bellied frogs were cocked on sods", caused him upset.

"Their loose necks pulsed like sails/ Some sat poised like mud grenades". The boy ran from those "great slime kings".

About two dozen kings and queens were gathered in pond turmoil last week in a particular woodland place in Meath where males fought to win females and some might die from exhaustion. Pairs can remain in spawning posture for days, even weeks, before the spawn is shed suddenly, up to 3,000 eggs in one batch. The male simultaneously fertilises them. Spawn floats in mats swelling in water, collecting together from numerous amphibians.

Spawning frogs are considered a significant sign of spring's arrival but in recent years their numbers have fallen considerably and sightings are fewer. This is due to increased land drainage and pollution. Sights such as the youthful Heaney witnessed are not so common. Last year I saw just one which had been attracted to a water source in an old sink.

Irish frogs are of the common genus, rana temporaria, whereas in Britain there are also found marsh (r.ridibunda) and some edible (r.esculinta). The marsh fellow is the biggest in Europe, brown-green with black spots which can be up to five inches in length. The edible one is a sort of refugee with a yellow stripe on its back, the plump hind legs being the portions presented on a dinner plate. Millions of these hind legs, which taste somewhat like chicken, are eaten by the French. I wonder if any were served up in Dublin's fashionable eateries last weekend?

Once, in one such place, I set about seriously infused garlic 'chicken legs' but found the 'bird' required concentrated chewing and gave up, to the amusement of companions who had ordered the food! Most of these frogs are imported from India, I learned.

The poor common frog, having sat out winter in the mud of ditches and ponds absorbing oxygen through its skin, spawns in this month, finding its way to breeding grounds by following the distinctive smell of glycolic acid produced by water algae.

The eggs become tadpoles in two or three weeks like tiny wriggling fish equipped with gills. Gradually the gills disappear and hind legs develop after seven weeks, front ones at 12. But only a small number of juveniles reach maturity as there are numerous predators about, from diving beetles to fish and birds. Mature frogs are themselves also seriously endangered from grey herons, buzzards and foxes.

Toads are larger than frogs but there are none in Ireland except the natterjack (bufo calamita) which runs rather than hops and, during the summer mating season, gives out raucous calls at night which can be heard up to a kilometre away. They may be found in some isolated places in Co Kerry but nobody knows how they got there.

Sunday Independent

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