N.Z. FROGS ARE TOADS

Press, Volume LXXII, Issue 21744, 28 March 1936, Page 14

N.Z. FROGS ARE TOADS

Introduction From Australia REASON FOR SCARCITY IN CANTERBURY What New Zealanders call frogs are toads, and even these are immigrants from Australia and not natives, according to Professor E. Percival, of Canterbury College, who commented yesterday on a London message about the value of frogs in the destruction of insects. Because of the arid conditions prevalent on the plains, he said, toads were less.common in Canterbury than in other parts of New Zealand. Actually there was one native genus of frogs in New Zealand, but it was relatively rare, and found chiefly in parts of the Auckland province. Its chief peculiarity was that its tadpole stage was passed inside the egg membrane and not in the water. The eggs were found under logs. The so-called “frogs” known to most New Zealanders were toads introduced from Australia. The best known—the common green “frog”—belonged to a genus of tree toads, and had sticking discs on the toes so that it could hang on to steep surfaces. A second imported toad—the little whistling “frog”— which was found abundantly on the West Coast, had more efficient sticking discs, and could even hold on to an inverted pane of glass. * Family Likeness The difference between a toad and a frog would not be noticeable by anyone without special knowledge. There was no obvious external difference, and none in the habits of the two families. In the tadpole stage the toads introduced into New Zealand were chiefly herbivorous. It was probable, since the green “frog” spent so much of its time in the water, that it would be useful in keeping down aquatic insects. The adult toads were carnivorous, but would take only moving objects. They would sit indefinitely in front of food, but would not see it until it moved. Then they moved very fast indeed. Both the green tree toad and the whistler were introduced deliberately. Attempts were made in 1864 to introduce the European brown grass frog to Canterbury, but although a were released there had been no record of them since. The common European toadwas introduced, at Gisborne jn. 1893, but after on#* or two yeafs these also disappeared. “The distribution of toads will depend on the amount of water and the. humidity,” said Professor Percival. “It is my experience that in Canterbury they are very locally distributed, being confined' to the immediate vicinity of ponds,; which are comparatively rare. Toads in Canterbury do not seem to be found very far from water, and it is probable that they play no very large part in insect control in such a seipidesert environment. In the damp of Westland they abound. Professional Frog-catchers ; “In England there is no difficulty in getting frogs lor dissection. The professional frog-catchers can go in the autumn into the harvest fields and find 10 or 12 frogs under every stock of wheat. In England in the spring the common toads migrate from their winter hibernating place to a near pond, and round all ponds for days the ground is covered with them. For nine or 10 feet round such a pond the ground may be covered with them, and the water afterwards is like sago with their spawn. That does not apply here. “It seems that toads in Canterbury spend the winter at the bottom of the pond, that they breed in it, and spend their summer in the same one. The smaller numbers here cannot be accounted for by the depredations of enemies, for if anything, toads have more natural enemies in England, including snakes and herons, than in New Zealand. Possibly eels may reduce their numbers, but the limiting factor appears to be climate.”