Tropic Days | Page 7

The tides then approach their maximum, flooding areas
denied three months previously. Wholesale tragedy was inevitable. The
full moon brought bereavement to many parents, for the sea
overwhelmed the nurseries, or the best part of them. Many wise birds
had laid their eggs above the limit of the highest tide. Others screamed
in protest against the cruelty of the sea, for eggs and fluffy chicks do
not surely represent legitimate tribute 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