THE BEAST OF PREY

Forest and Bird, Issue 46, 1 November 1937, Page 10

THE BEAST OF PREY

By Authenticus.

HIS SUPERIORITY TO PREDATORY MAN

Carnivore Flesh-eating animal. Herbivore —Plant-eating animal. Bioticßelating to wild life. Feral—

Animals that prey, and the animals they prey on, are equally part of the balance of nature. Where this balance has been gradually produced by centuries of time, it should on no account be disturbed. The natural enemies—the animals that prey —should not be made war on by man. If he makes war on them, he makes war also upon their prey. He cannot preserve the prey by exterminating the natural enemies.

Voices bearing this message came across the Pacific from the United States and Canada. Dr. Joseph Grinnell, ornithologist and mammalogist, of the University of California, writes that “ the population of carnivore and of herbivore tends to maintain a mean ratio from one period to another.” Balanced, the carnivore and the herbivore animals that prey, and the deer and other creatures preyed onare necessary one to the other. If man destroys the carnivore, the deer are not better for that. They are worse. Protected red deer in Scotland exemplify this principle. There are many other examples.

Herbivore without Carnivore.

If New Zealand was being entered by the white man to-day, he should, on this evidence, import no animals whatever, unless he can guarantee that they will not become wild. Certainly he should not introduce animals intended for wild life.

Unfortunately, he did this very thing when he introduced deer. He ignored the fact that deer in New Zealand would meet with no natural enemies. He violated the first principle of the doctrine of balance between herbivore and carnivore.

That doctrine now tells him his error, but is unable to tell him how to retrieve it. To try to counter-balance the excess of deer by intro-

ducing animals that prey on deer would mean an attempt at a man-made balance. Obviously, it is risky. How can a man-made balance provide the results that are provided by a balance which Nature took many centuries to build, using, for that purpose, many species? Man may juggle with this animal and with that; he may import the rabbit, and then import the weasel and stoat as a cure for the rabbit. Hitherto, with each fresh step, he has floundered deeper into the bog. But nowhere has he equalled the “ biotic complex ” created by Nature in uncounted ages.

Adjusted Biotic Complex .

To again quote Dr. Grinnell, in a place where animals have existed “from time immemorial, as parts of the perfectly normal biotic complex’’a complex not copyable by acclimatisation authoritiesthose animals are mutually “adjusted,” by reason of rates of reproduction “long-established,” and, in the presence of predation, “wholly adequate.” Man may leave this balance alone. Or he may upset it. But, if he upsets it, and seeks to balance one importation with another, let him beware lest he blunder again, as with the weasel and stoat.

In any case, as Captain E. V. Sanderson points out in a communication to the Controller of Canadian Resources, dealing with the deer in New Zealand, “the introduction of the natural enemy is unthinkable from the point of view of the pastoralists.” Captain Sanderson, asked by the Controller of Canadian Resources for a statement of the position in New Zealand, found himself forced to the conclusion that if the deer cannot be fought by a natural enemy, they cannot be kept within reasonable limits by the human enemy. As a natural enemy, man is very inefficient. When man acts in the role of a deer-stalker, “he takes the cream of the male stock, and therefore reduces the stamina of the deer herd. On the other hand, the less well equipped

enemies, such as wolves, tigers, cougars, etc., having no guns, usually have to be content with the weak and less agile members of the herd. Thus, animal natural enemies assist in maintaining the stamina of the species preyed on” by reducing its numbers in a way leading to the survival of the fittest.

Limits of War on Deer.

If the object of the deer-stalker is quality and not quantity, then animal predation is far more efficient than he.

But when man acts in the role of a killer of deeras by Government shooting parties, payment for tails, —he still fails in New Zealand, because, “owing to the extremely rough nature of the country and the mountain ranges, the natural increase cannot be kept within reasonable limits.”

Captain Sanderson’s outline of the New Zealand situation, Dr. Grinnell’s defence of natural enemies as being necessary to any balance built up by Nature on predation, and other interesting contributions to the balance of wild life, were brought before a conference in Canada on wild life, attended by delegates of Canadian Provinces. Representatives of British Columbia, Ontario, and New Brunswick, and other delegates, emphasised the need for further observations in Canada of the effects of predation, with a view to testing whether the human war on indigenous predatory birds (such as hawks) and animals is a fallacy.

And here arises a related question: Is it not possible that the Government’s war on deer in New Zealand may merely result in better quality herds, for the Government’s war is not, like the deer-stalker’s, selective, but merely tends to delay the time when the deer will increase to starvation numbers?

A Culminating Accident.

Seeing no solution in this Governmental war, and realising that pastoral opinion would prevent any experiment in the way of importing a natural enemy, Captain Sanderson hazards the suggestion: “Perhaps the final solution will be that some domestic dog, like the Alsatian, will become feral.”

Such a culminating accident would be an ironical comment on the planlessness of New

Zealand’s acclimatisation plans, ever since the weasel blunder was added to the rabbit blunder.

But if the correction of mistakes like rabbit and deer has become impossible, at least let us begin to learn something about the part played by predation in Nature’s balance, and therefore cease our war on hawk and shag, who are good New Zealanders, and who. to use Dr. Grinnell’s words, have been in New Zealand “from time immemorial, as parts of the perfectly normal biotic complex.”

THE FOOD OF NATIVE BIRDS OF PREY.

There is no lack of reliable, scientifically accurate information on this subject. The most extensive investigations were made by the Biological Survey and published in 1893 by the United States Department of Agriculture in a report by Dr. A. K. Fisher, entitled, “The Hawks and Owls of the United States in their Relation to Agriculture.” Though many later observations and investigations have been made, Dr. Fisher’s work, based on the examination of the stomach contents of 2,700 of our native birds of prey has been substantiated in all its main points and is the basis for much of the information contained in later works. But in considering these figures, it should not be forgotten that many, if not most, of the birds of prey will feed on birds or animals they find dead, even if they are not at all in a fresh condition, and that the presence of bones in a bird’s stomach is by no means a proof that it killed the animal or bird to which they belonged. (See the above work of Dr. Fisher, page 63.)

“Only when large numbers of our citizens take a personal interest in conservation can we have confidence that progress is being made. . . It would be a mistake if we did not make a special effort to teach our children the fundamental lessons of conservation to the end that our beautiful natural resources may be transmitted as a sacred trust for the continued enjoyment of future generations.” Governor La Follette, Wisconsin.