The New Zealand Railways Magazine, Volume 6, Issue 4 (September 1, 1931.)
Cupid in Birdland — Territorial Battles
Nature, we are told, has many moods! Apart from that aphorism we may go so far as to qualify her as a “paradox”; at once kind and cruel. Her laws are more rigid and unalterable than those of the Medes and Persians, the least infringement bears but one penalty—death! There is no middle course: she showers, with the same hand, kindness and (seeming) cruelty—life and death!
Can any reader of this—and there are many competent to say—recall a single instance of seeing a malformed or cripple creature of the wild? Just think it over! One of Nature's most fundamental laws is the “survival of the fittest.” She has neither time nor place for the degenerate, the unfit, the slothful; they must perish by the wayside.
Concomitant with, or subsequent to this law, is that of “selection”; the most vigorous and strong are the chosen and elect for procreation. The mates are compelled to do battle, as did the knights of old, for conquest and preference; whether it be for mating or for home-site—it is all the same thing, the prize to the victor!
After this prelude it is intended to touch on bird-life in this article. Spring is swiftly approaching our shores; soon another “winter of our discontent” will belong to the past; and Nature, omnisciently soaring, will garb herself in gala raiment; the song of the turtle (dove) will be heard in our land; the call of the cuckoo, the symphony of the tui ravish and enchant our listening ears. Our migratory birds will return to our shores rejoicing in “homing” again.
With some species the domestic phase will have been completed elsewhere; others will arrive intent and eager for home-building, obsessed by the all-compelling instinct of reproductivity. We can not ascribe this state to anything but instinctive intention; there does not appear to be any intelligent forecasting of events that are to follow; nor can we recognise, in any small degree even, the knowledge of experience. The ways of young birds entering into a nesting state for the first time do not in manner differ from those of others who have reared many broods.
Firstly, we may note that “selection” occupies a most prominent part in Nature's scheme. Both male and female are affected, those whose “fitness” is waning are backward in the power of procreation; either their broods will be entirely absent, or hatched out too late, and as a consequence weaklings that cannot be reared.
For purposes of explanation birds may be placed under two headings:
Those that nest in colonies, and whose food supplies are plentiful. These are not prolific, some laying only one egg.
Solitary nesting birds, sub-divided again; the carnivores, whose food supply being restricted, require wide hunting range and scope: those whose nesting sites are extremely limited.
This, in the latter class, gives rise to sanguinary territorial battles; and, the territory, once occupied, is jealously guarded against intrusion. A laggard arrival, imbued with poaching intentions, is in an awkward predicament, he will be obliged to battle with, not one antagonist, but the nesting pair.
The males are always the first to arrive, often a week ahead of the females. It is their duty to annex and hold preferable sites for their future nurseries, governed by two factors—suitability as to position and of food supplies. When the females page 64 put in an appearance they are guided to their future mates by the means of songs and calls.
As regards the gregarious nesters, attention may be drawn to the communal weaver bird of the tropics that constructs such enormous community nests that one will contain whole cartloads of material. The “scrub-turkey,” of Australasia, builds communal mounds, as nests, like small hills. Here mention may also be made, in this class, of terns, gannets, cormorants, and other such “fish-preyers.”
Amongst the solitary builders, whose food supplies are restricted, we may make mention of the larger falconidæ who, of a necessity, need large and extensive hunting grounds. Conspicuous amongst these is the fearless and savage Peregrine; intolerant of intrusion.
The skua-gull, another fierce defender of territorial rights, is a welcome home-builder in Scotland. So fiercely does the skua protect his demesne that, that overlord of the air, the golden eagle, is compelled to relinquish the vicinity. Very swift of wing and powerful of beak and talon, the skua pair will attack and put to ignominious flight any eagle bold enough to intrude—the aerial battle being a sight well worth witnessing.
Again, the raven requires extensive preserves; yet, this bird is not altogether unsocial. If digression, to an extent, be permitted, an instance of “communal instinct” may here be quoted that goes far to shew that birds are capable of conveying thought and idea to one another by means of—shall we say—“bird language.”
Passing through the mountainous country near Myrtleford, in Victoria (Australia), it fell to the writer's good fortune to witness an evidence of this trait in the ravens. An “eagle-hawk”—the largest of the world's eagles—approached a raven nursery. The parent ravens sped away in different directions, and were soon seen returning with reinforcements. The two parties joined forces rapidly, formed up—as it were—in battle order, attacked the formidable marauder, and put him to ignominious flight.