He Who Croaks Loudest

Auckland Star, Volume LXIX, Issue 208, 3 September 1938, Page 3 (Supplement)

He Who Croaks Loudest

SEVENTY years ago New Zealanders were unaccustomed to the croaking frogs, for only a small, uncommon and locally distributed species was known to exist here. It is now difficult for us to realise that the common frog responsible for the nocturnal commotion in the swamps is no New Zealander but an importation from Australia. The first consignment was introduced by the Auckland Acclimatisation Society in 1867, and shortly afterwards they* were introduced into Otago. There is no need to inform 1 readers as to the success of these introductions, they croak for themselves. Attempts have been made to introduce four species of frogs but only two of these efforts have succeeded, the now generally distributed Australian green frog, Hvla aurea, already referred to, and the small brown tree frog, Hyla Ewingii, which has survived only in Westland. The common Australian green frog is a really handsome creature in its coat of bright green and gold with brown markings, a much brighter raiment than our New Zealand native species can show. The late Mr. G. M. Thomson, in his excellent book "The Naturalisation of Animals and Plants in New Zealand," tells of the remarkable vitality possessed by the green frog. One of these frogs lived in an ornamental fern-box which he had in the house. During an absence of six weeks the ferns were not watered and all were dead and the soil dry and hard on his return. The fern-box was cast aside in a lumber room i until a year later a start was made to refill it * when, to Mr. Thomson's surprise, he noticed a hard, dry lump of clayey soil about four inches in diameter which had not been in the Qase formerly. On breaking this lump open he was amazed to see inside the old frog quite cool and collected. The frog was placed under a glass shade in company with a house fly, which the frog quickly caught and devoured. Unfortunately the frog after this great exhibition of endurance met disaster by a strange turn of fate. A bull's-eye condenser stood on a table nearby and a ray of sunshine caught by it" focused on the unfortunate frog under the glass cover and caused its death within half an hour.

By-

A. FT. B. Powell

The power of endurance shown by certain frogs has been responsible for the belief that some frogs found in rock cavities must have been imprisoned there for millions of years. Certainly frogs have been found in rock cavities where there was no apparent way of entry, but the fact is that either the egg, tadpole or very young frog, had been washed into a crevice, then down through a crack into a pocket, the entrance filled up and the imprisoned frog grew to completely fill the pocket. In t-uch a place a frog migCt remain for years, provided air and moisture reached it. A British scientist proved that toads could live a very long time in a state of hibernation," provided air and moisture reached them, and in proving this he prepared two blocks of stone, one limestone, one sandstone; in each of these he bored three holes, and into each hole he placed a toad, cementing a glass lid over the top. The stones were buried three feet in the earth, and left there for eighteen months. On being dug up, the toads in the limestone were found to be dead, limestone being impervious to air, but those in the sandstone were alive, both air and moisture being able to penetrate the-rock in which they were held captive. Our native frog is a small creature, seldom exceeding one and a half inch in length, brownish in colour, mottled with darker brown, and the skin very rough and

warty. Its chief claim to distinction, however, is in its modified life history, which was revealed some 15 years ago by Mr. Gilbert Archey, then of the Canterbury Museum. It was found that these frogs, on the Tokatea Ridge, Coromandel, did not inhabit the streams at all, but lived under logs and rocks on the crest of the ridge. Furthermore, the egg-clusters, enclosed by membrane, were found in the came situations. The subsequent development of the frogs was observed in specimens taken to the Canterbury Museum, and was found, in the absence of aquatic environment, to take place within the egjf. .There is bo free-swimming tadpole stage, after five weeks a minute-tailed frog emerges from the capsule. A yolk-sac is still attached to it, and from the frog derives nourishment for ■ a month or more. This modified life history is an adaptation to special climatic- conditions. The higher ridges of the Goromandel range lack surface water, but they are not dry or arid. . On the contrary they are almost perpetually mist-driven, sad it is the constantly humid atmosphere which has enabled the native frog to become independent of pools streams for breeding purposes. This specialised life history is not peculiar to our native frogs, for a Solomon Island and a West species, both living in mountainous country, have this same life history. The native frogs, of which there are two known species, have long been considered of great rarity, but now that we know their habits, and are not led astray by looking for them in ponds and streams, additional locality occurrences are being recorded. Originally this frog, now known as Liopelma Hochstetteri, was discovered by gold miners in 1852 st CoromandeL Xow it is known from the length of this range, eastward as far as Opotiki and near Huia in the Waitakere Ranges. At the latter locality, which is in a stream bed in dense rain forest, it may yet be found that these Huia samples represent a race that have a normal aquatic life history, particularly as they are found under stones at the edge of streams. Our second species of native frog is Liopelma Hamiltoni, found in 1919 on tbe small rocky and streamlets Stephen Island in Cook Strait. The nature of the locality suggests that Hamiltoni hss a modified life history similar to that of -the-typical Coromandel Hochstetteri.