NATURE NOTES

Evening Post, Volume CVIII, Issue 24, 27 July 1929, Page 17

NATURE NOTES

VALUE OF BIRD LIFE

RELATION TO AGRICULTURE

(By R. H. D. Stidplph, R.A.0.U.)

The agriculturalist is probably at much concerned with birds as any resident of the country, as it is from him that a large number of complaints about the ravages of birds come to hand. The grower of wheat or oats, or sonic such cereal, has in many instances, cause for regarding certain. birds with unkind feelings, but the Jone important fact to remember is that the great bulk of the damage to crops is committed by species introduced into New Zealand from the Old Country. la few cases, if any, is a bird native to New Zealand concerned in the charges. It may be as well to point out that ia the first place, the introduced species which are the subject of producers' condemnation were liberated in New Zealand with the object of making cultivation possible. Consequent upon the removal of the. forest or bush for cultivation purposes, insects and their larvae increased at an alarming rate and threatened the very existence of the settlers' crops. That increase was made possible by reason of the fact that the native land birds, which aro largely dwellers of the forested areas retired witli the destruction of the vegetation, leaving tho insects a profitable iield for multiplication in tho absence of natural enemies, the principal of which wore birds. There are records from several districts of New Zealand which show that in many cases promising crops were actually ruined at the months of devouring insect hordes. The loss of crops compelled the settlers to band together and acclimatisation societies were formed to introduce into New , Zealand birds which it was thought would check the insects' ravages. :

On account of the possible absence of insect food- in the winter months it was considered advisable by these societies to introduce birds whose diet consisted of seeds as well as insects, mat determination was responsible for the acclimatisation of such birds as the song thrush, blackbird, chaffinch greenfinch, goldfinch, yellow hammer' redpole, linnet, sparrow, starling, and hedge sparrow, all of which have become thoroughly established in the Dominion. The skylark, which was also introduced, was probably brought to *ew Zealand for sentimental reasons as well. In addition, there were many other species introduced, but the'great percentage of these, failed to establish themselves. Although the advisability of bringing into the country certain of the species enumerated above is questionable, it must be admitted that the birds accomplished the object tor which they were introduced—the suppression of insect pests and makingcultivation profitable. Some of the species-have increased enormously, and now a re the most numerous birds inhabitiug fcew Zealand. In certain districts, where they become too numerous these alien species are certainly harmful, but usually only for a short period ot the year, for the remaining eleven months carrying out an effective war against insect pests.

A tew species of native birds have accustomed themselves te the altered conditions brought about by the settlement and cultivation of the country and are rendering good service to the agriculturalist. Others again have benefited by the clearing of the land, and with an increase in food supply have become more numerous and nioro widely distributed: Notable native birds of insectivorous habits which frequent the countryside are the fantail the grey warbler, and the pipH or ground lark. Every one of these birds are purely insect-eating species, and are o± inestimable value to the country. Fortunately,. they have .farsd better than many other useful specie's which found competition too strenuous and life impossible under the changed conditions, but some of these still exist although in sadly depleted numbers, m some of the more remoto districts in winch the native forest still exists. Although every encouragement should be given to the native species which have survived in settled districts, it appears to be apparent that New Zealand, at the present time, could ill afford to be without the services of the introduced birds, which are necessary for the well-being of the country from a tanning point of view. The amount of insect food consumed by these alien species m a twelve mouth must be prodigious. As already mentioned, howover, many of these "birds take a toll of crops and perhaps fruit as a payment for their services, but it is questionable if even the much despised sparrow can be roundly condemned as a useless and wholly injurious species. It performs many good services, and its economic position is determined largely by its local habits. In some districts it can be distinctly detrimental to farming interests, but in others it can be of use. Much the same can be said of several other introduced birds There are a few acclimatised species however, which are almost wholly beneficial m all districts, such as the goldfinch, the hedge sparrow, the redpoll, and the so-called magpie of Australia.