Wednesday, February 14, 2007

Toadspawn Is Quite Unlike Frogspawn

The frogs are quite difficult to see in the loch, because it is mostly dark and deep, but in one of the shallower bays is a whole group leaping and splashing about. You have to be very quiet as you walk towards them because they are surprisingly alert and if they are alarmed then all you see are ripples on the water as they dive to hide in the mud and vegetation below the surface. But if I walk very quietly and sit gently on the bank above this particular place, I soon see the frogs swimming in the cloudy water. Slowly they return and carry on with the business of display. Some are giving their mating calls, their throats blowing up to produce beautiful croaking calls which carry a long distance. I remember once hiking in the mountains when I heard frogs calling at an altitude of nearly 3,000 feet. I tracked them to a small hill loch nearly a mile away. They were in full mating frenzy in the shallows while the other end of the loch was still imprisoned in ice.

Back in the warmer water of our loch the successful males are holding tightly on to their mates, the forelegs clasped across the female’s back. Some females have already laid their eggs, with masses of frogspawn floating in the water. This is a particularly good place for the frogs to spawn because soon there will be plenty of algae in the water for the young tadpoles to eat. There are also plenty of places for them to hide and room in the whole loch for them to grow up until they become real frogs and leave the water in the summertime. I often think that frogs are either incredibly careless or very skilled at taking advantage of every opportunity, for on my walks through forests and fields I sometimes come across frogspawn in tiny pools of water which have formed in the tracks of a large vehicle that passed during the winter. It is wet and well flooded in March, but later in spring I find it dried up and the frogspawn dead. There are advantages for the frogs in using shallow pools, because the water is warmed more quickly by the sun and the young frogs hatch earlier.

Toads breed in the loch, but they tend to keep to themselves in a different part of the water. They also seem to be more careful, because I never see toadspawn lying around in temporary pools, although in general they prefer to lay their eggs in cooler water. Toadspawn is quite unlike frogspawn: it is laid in long chains hanging in the underwater vegetation rather than in great big masses.

Roy Dennis
The Loch: A Year In The Life Of A Scottish Loch

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