NATURE NOTES

New Zealand Herald, Volume LXX, Issue 21520, 17 June 1933, Page 1 (Supplement)

NATURE NOTES

BY 3. DRUMMOND, F.L.S., F.Z.S.

BUTTERFLIES' COLOURS

Mr. G. V. Hudson, in his large and beautifully illustrated volume on New Zealand's moths aud butterflies, has a clever chapter on the remarkable colours of these insects. Their wing patterns, he explains, are so varied that they resemble almost every possible environment, including bark, moss, dead leaves, lichens, twigs, seeds and petals of flowers. He finds it almost impossible to draw the line between merely ornamental colours and colours that are useful for protective purposes, enabling the insects to hide from enemies. The males often, by no means always, are more brilliant than the females.

The most important explanation of bright colours in insects and in all other creatures is Charles Darwin's theory of sexual selection. This sets out that in most species there are more males than females. On account of the greater number of males, the females, when mating, have a choice. They may mate with males they prefer, jilting males they do not prefer or dislike. They exercise sexual selection. The females are influenced in their choice by the males' bright colours, and by frills, tufts and other ornaments, but mostly by the colours. The colours and the ornaments are charming in the females' eyes. They excite them, to the disadvantage of the plainer males.

The theory of sexual selection took the world by storm when Darwin first put it forth. In these days of'worldwide investigation it is somewhat discredited or is brushed aside. A long, careful and extensive study of New Zealand's moths and butterflies has left Mr. Hudson convinced that sexual selection has exercised a profound influence on the evolution of species. He knows of no theory except sexual selection that explains adequately the' extraordinary colours, marks, and structures in many male insects. Opponents of sexual selection argue that an impossible measure of intelligent discrimination is attributed to females when they are credited with ability to choose the most brilliant males. The critics ignore the abundant evidence that insects know much more than human beings give them credit for. In any case, Mr. Hudson points out that even man seldom exercises his high intelligence when he mates with the opposite sex. Human beings are no better than the insects when mating is concerned.

A new theory is offered by Major R. W. G. Hingston in a book of 400 pages entitled " The Meaning of Animal Colour and Adornment." He is a naturalist with unusual powers of observation. His work is original. His first contribution to science was " A Naturalist in the Guiana Forest," charmingly written and delicately illustrated. He followed this with an absorbingly interesting study of instinct and intelligence. His latest book is profounder than the others. His theory is that males' colours are rather an expression of fear and anger, associated with members of their own sex, and used in their conflicts for females. Fear and anger, he argues, are the dominating emotions in all creatures, from mammals to insects. They are expressed externally by two opposing colour patterns. One of these helps them to conceal themselves from enemies. The other is threatening. If fear predominates, the concealing pattern predominates in the colour scheme, and the creature blends more closely ■with its environments. In anger, colours and ornaments become conspicuous. Elsewhere Major Hingston has noted the same butterflies' characters as Mr. Hudson has noted in New Zealand's butterflies. He has seen many butterflies that resemble dead leaves, not only in colour and markings, but also in mimicking midribs and cross-veins. He has seen moths with wing-colours that harmonise perfectly with rocks, stones, leaves, sticks, lichens and bark. Butterflies are the most gaily-coloured creatures in the world. According to Major Hingston, male butterflies fight with their colours only. As colours are their weapons, £hey require colours in a high degree. They are supreme in the splendour and profusion of their war-paint, Male moths and female moths do not differ greatly in colours. The explanation offered is that male moths compete mainly by smell, and that in their case difference in colours from females is unnecessary. Major Hingston's theory has not been subjected to the test of investigation and criticism. It will be adjudicated upon later. In the Darwin's theory stands as the simpler one and the most probable. This book throws light on antics and gesticidations in courtship, and on the significance of song. A bird's song is regarded as an act of rivalry. One bird tries to emulate another, to shout it down. Chaffinches sing against each other, their efforts ending in combat. Song-thrushes answer one another. Major Hingston describes song as a gesture between male and male. If it is a gesture between male and male, he asks, what is behind the ggsture except threat and hostility? It may bo said that males compete with each other in order that a listening female can chooso the most melodious. This is dismissed as impossible, because the songsters almost always are far apart; one male is close to the femalo in the male's own territory; tho other male is remote. If both competed for tho female's favours, both would go close, or would sit at equal distances from her. The rivalry agrees with the view that its utterance is a threat. Song is the males' long-range artillery in action. Major Hingston's book, full of information about insects, birds and mammals, is published by Messrs. Edward Arnold and Co., London. A few years ago Mr. H. Cundall, of Broadway Avenue, Timaru, reading about the sufferings of birds in tho winter, fastened two kerosene tins on a post in a quiet corner of his garden. After breakfast every morning lie' put out a few handfuls of crumbs. It'was not long before there was a number of visitors, including twenty-four whiteeves or wax-eyes. Year after year they came, probably tho same individuals. This year there are only twenty, darting and twittering, and Vorv pretty in bright olive, dark grey, yellow, white and chestnut. First comes a magpie at dawn, then a blackbird and a songtbrusli. The—white-Dies uro airaid of all other birds except sparrows, which they chase away. As many as ten whito-oyes get on to tho tin at one time. Mr. Cundall reports tlint they are so gentlo and sprightly that even a bed-ridden person would be interested and amused by them if tho ,bed Avas near the window anu if somebody rubbed a piece of stalo bread on a grater aitd offered the crumbs to the visitors. One night a few weeks ago Mr. Cundall heard :v noisy twitteriug. He thought that his little friends had. returned. Although the night, was too dark to see, tho volume of sound seemed to show that there were hundreds. Only twenty-four attended for breakfast, but Jklr. Cundall was pleased to find that his visitors had not -deserted his place.