Art. XIII.—Note on the Breeding Habits of the European Sparrow (Passer domesticus) in New Zealand.
[Read before the Wellington Philosophical Society, 2nd July, 1890.]
It is my ambition to lay before the society at a future meeting a complete history of the sparrow in New Zealand, its introduction, distribution, rate of increase, the various influences affecting that increase, such as climate, food, &c., together with a quantity of evidence both as to its insectivorous and grain-devouring proclivities, its influence upon the various branches of horticulture, and the means of checking the too-rapid increase, &c.
Being struck with the spirit of partisanship which pervaded most discussions on the so-called sparrow question, I some years ago decided to collect all the obtainable evidence having any possible bearing on the subject, with the result that a large mass of material has accumulated in my hands. But, on attempting to work it up, I found that much more must be done before the history can be considered complete, and a fair and impartial judgment given. For instance, I have the opinions of many persons on the question of whether the sparrow does more harm than good to agriculture; but mere opinions, unless backed by evidence, do not carry much weight, and the point can be settled only by the examination of large numbers of specimens. I have myself dissected fifty-three birds, taken at all seasons of the year, and am forced to admit that the remains of insects found in them constituted but a very small proportion of the total food. I may mention that a record has been kept of the sex and contents of each of the birds obtained; but some hundreds, captured systematically at various seasons and in various localities, will be required before a reliable “food table” can be constructed. So with regard to the rate at which they have spread and are spreading over the country, I find my notes from several districts in complete. More detailed information is required as to their treatment of fruit.
The account of the most approved methods adopted in other countries for keeping their numbers somewhat within bounds is, I think, tolerably complete. But further inquiry is necessary as to how far our native birds are injuriously affected by the all-pervading sparrow. I have therefore to-night confined myself to one section of the subject; and the statements, though brief, are the result of numerous inquiries and of lengthened personal observations. It is hoped that their pub-
-lication may induce other persons who have made reliable notes to help by recording their observations and experience.
I shall assume, for the purposes of the calculation I am about to make, that no extensive action is taken by man for the destruction of his small opponent, if such he is to be called; and, as the natural enemies in this country are hardly worth mentioning, we will allow only for accidental and natural deaths.
Speaking of the natural enemies reminds me of an incident I once noted between Featherston and Martinborough, showing to what lengths the daring and cool impudence of the sparrow will sometimes go. Hearing a most unusual noise as though all the small birds in the country had joined in one grand quarrel, I looked up and saw a large hawk (C. gouldi— a carrion-feeder) being buffeted by a flock of sparrows—I should say several hundreds. They kept dashing at him in scores, and from all points at once. The unfortunate hawk was quite powerless; indeed, he seemed to have no heart left, for he did not attempt to retaliate, and his defence was of the feeblest. At last, approaching some scrub, he made a rush indicative of a forlorn hope, gained the shelter, and there remained. I watched for fully half an hour, but he did not reappear. The sparrows congregated in groups about the bushes, keeping up a constant chattering and noise, evidently on the look-out for the enemy, and congratulating themselves upon having secured a victory. I have heard of sparrows attacking and driving away pigeons and other birds, but do not remember any record of their daring to attack a hawk.
In this part of the colony the breeding-season of the sparrow begins in spring and ends late in the autumn—the first broods appear in September and the last in April.
I have examined a great many nests, but never found less than five eggs under a sitting bird—more often six, and frequently seven. These are usually all laid in one week. Incubation occupies thirteen days. The young are fed in the nest for eight or nine days; they then return to the nest for two or three nights, after which they have to feed and lodge themselves, sometimes assisted by the male bird. In five instances fresh eggs were found in the nest along with partly-fledged young. Both parent birds work in feeding the young till they leave the nest, and at first I was much puzzled to account for the fact that the second laying of eggs was not spoiled during the absence of the mother. From my observation I am convinced that the chief portion of the work of incubation—that is, after the first brood is hatched—is thrown on the young birds; for it must be apparent that the heat arising from the crowding of five or six young birds into a nest would be sufficient to cause incubation: so that by the time
the young birds are finally turned out the earlier-laid of the next batch are within a few days of issuing from the shells. Therefore the mother is confined to the nest for little more than half the time required to hatch the first brood of the season. Then, after a very few days, the process is again repeated.
This does not occur in every nest, but it is a very important item to be noted when considering the “rate of increase.” Moreover, in one instance at least the young birds belonging to the first brood, reared in September, were themselves breeding at the end of March. I can speak positively, as, in the hope of proving whether the birds of one brood mated among themselves, I fastened a bit of red stuff around the leg of each. The only one I saw after they were turned out by their parents was a hen, which had mated with a male from another brood, built a nest close to her old home, and actually reared a brood of her own at the same time as her mother was closing her arduous duties for the season.
From two nests I was able to prove that seven broods issued the year before last, but, for the purposes of the calculation I am about to make, we will take it that the average is five broods of six each. This is below the mark. We then allow one-third of the annual increase for deaths. Here are the results:—.
First year: 1 pair: 5 broods of 6 each = 30 - ⅓ = 20 + original pair = 22 = 11 pairs.
Second year: 11 pairs x 30 = 330 - ⅓ = 220 = 110 pairs + original 11 pairs = 121 pairs.
Third year: 121 pairs x 30 = 3,630 - ⅓ = 2,420 = 1,210 pairs + original 121 pairs = 1,331 pairs.
Fourth year: 1,331 pairs x 30 = 39,930 - ⅓ = 26,620 = 13,310 pairs + original 1,331 pairs = 14,641 pairs.
Fifth year: 14,641 pairs x 30 = 439,230 - ⅓ = 292,820 = 146,410 pairs + original 14,641 pairs = 161,051 pairs; or an actual increase, after allowing for deaths, of 322,100 birds.
This does not take into account those early broods which are themselves breeding, nor does it allow more than five broods a year, while six and even seven are of common occurrence; further, the clutches of eggs often number more than six: so that we started on a low basis. And the allowance of one-third is, I think, more than ample.