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?