Tropic Days | Page 7

to Neptune. Several fledglings were found half buried in sand and coral chips, some with merely the head with bright and apprehensive eyes obtruding. Why were not the whole of the parents of the colony prudent when in default the penalty was inevitable? Five score were wise, five hundred were foolish, and the natural increase from the second brood must have been seriously diminished. Several of the parent birds had brooded over their eggs until overwhelmed by the surges and drowned. Some on the tide limit squatted buried to the eyes in sand and seaweed. Of one the tip of a wing only protruded. It was alive, fostering unbroken eggs.
The metallic starlings have again built on a favourite tree--not massive and tough, but a slim though tall Moreton Bay ash, the branchlets of which are not notoriously brittle. They withstand a certain weight, beyond which they snap. Why do these otherwise highly intelligent birds so overstrain branches with groups of nests that "regrettable incidents" cannot be averted? First there came to the ground a group of four, and then twenty nests, all containing eggs or helpless young. By these and similar mishaps during the season the colony suffered loss to the extent of at least a hundred.
"But, like the martlet, Builds in the weather on the outward wall Even in the force and road of casualty."
How often, too, do we find nests in places absurdly wrong? Wonderfully and skilfully constructed nests are attached to supports obviously weak, and eggs are laid on the ground right in the track of man and less considerate animals. Some birds seem to lay eggs and rear young solely that snakes may not lack and suffer hunger, while how large a proportion of beautiful and innocent creatures are destined to become prey to hawks?
Years ago scientific visitors to a coral islet found almost innumerable sea birds and eggs. The multitude of birds and their prodigious fecundity inspired the thought that the "rookery" for the whole breadth of the Indian Ocean had been discovered. Investigations showed that the islet was also the abiding-place of a certain species of lizard which subsisted entirely on eggs. It was calculated that not one egg in several hundred was hatched out; yet in spite of such an extraordinary natural check the islet was enormously overpopulated. Thousands of birds every year laid eggs for the maintenance of fat and pompous reptiles, without reflecting that there were other and lizardless isles on which the vital function of incubation might be performed without loss. Years after other men of science sought the isle. Birds seemed to be as numerous as ever, but the lizards had disappeared. Had the birds been wise enough to perceive that the plague of lizards had been sent as reproof for overcrowding, or did the lizards become victims to physical deterioration incident upon gluttony and sloth?
"Into every instinctive act there is an intrusion of reasoned act." No doubt; but in the case of the terns--sea-frequenting and sea-loving--which had not the wit to lay their eggs beyond the reach of spring tides, the reasoning is the merest intrusion. Yet an instance of what seems to be the reasoned act of a wasp may be cited. The insect had selected a dead log of soft wood as a site for its egg-shaft. It was at a spot to which the occupations of the season took me daily, so that the boring operations were watched from beginning to end. The work was done rapidly and neatly, and when all was ready for the deposit of the eggs the insect constructed from papier-mache-like material a disc-shaped lid exactly fitting the mouth of the excavation, to which it was attached on its upper edge by a hinge. Then round and about the disc similar stuff was plastered, so as to form an irregular splash, imitative of a bird's droppings to the-degree of perfect deception. In the centre was the lid with the hinge, and whensoever the insect visited its nursery the lid swung up, closing behind it. On departure it fell into position. Unless the insect by its presence betrayed its secret, the shrewdest observer at close quarters would have been misled.
There are reasons for the belief that green tree-ants understand and respect the laws of neutrality. There are several communities in the mango-trees, and since some of the trees overhang the fence, the top wire is used as a highway. When a gate is opened traffic is suspended. In a minute or two of a busy day there will be considerable gatherings on the latch-style, and if the intervening space is narrowed by the swing of the gate the impatient insects begin to make a living bridge across the perilous gap. At one particular gate, which is opened and shut many times a