Professor Lloyd Morgan was foster-parent to two moorhens which grew up
in isolation from their kindred. They swam instinctively, but they would
not dive, neither in a large bath nor in a current. But it happened one
day when one of these moorhens was swimming in a pool on a Yorkshire
stream, that a puppy came barking down the bank and made an awkward
feint towards the young bird. In a moment the moorhen dived, disappeared
from view, and soon partially reappeared, his head just peeping above
the water beneath the overhanging bank. This was the first time the bird
had dived, and the performance was absolutely true to type.
There can be little doubt as to the meaning of this observation. The
moorhen has an hereditary or instinctive capacity for swimming and
diving, but the latter is not so easily called into activity as the
former. The particular moorhen in question had enjoyed about two months
of swimming experience, which probably counted for something, but in the
course of that experience nothing had pulled the trigger of the diving
capacity. On an eventful day the young moorhen saw and heard the dog; it
was emotionally excited; it probably did to some extent intelligently
appreciate a novel and meaningful situation. Intelligence cooperated
with instinct, and the bird dived appropriately.
Birds have inborn predispositions to certain effective ways of pecking,
scratching, swimming, diving, flying, crouching, lying low,
nest-building, and so on; but they are marked off from the much more
purely instinctive ants and bees by the extent to which individual
"nurture" seems to mingle with the inherited "nature." The two together
result in the fine product which we call the bird's behaviour. After
Lloyd Morgan's chicks had tried a few conspicuous and unpalatable
caterpillars, they had no use for any more. They learned in their early
days with prodigious rapidity, illustrating the deep difference between
the "big-brain" type, relatively poor in its endowment of instinctive
capacities, but eminently "educable," and the "little-brain" type, say,
of ants and bees, richly endowed with instinctive capacities, but very
far from being quick or glad to learn. We owe it to Sir Ray Lankester to
have made it clear that these two types of brain are, as it were, on
different tacks of evolution, and should not be directly pitted against
one another. The "little-brain" type makes for a climax in the ant,
where instinctive behaviour reaches a high degree of perfection; the
"big-brain" type reaches its climax in horse and dog, in elephant and
monkey. The particular interest that attaches to the behaviour of birds
is in the combination of a good deal of instinct with a great deal of
intelligent learning. This is well illustrated when birds make a nest
out of new materials or in some quite novel situation. It is clearly
seen when birds turn to some new kind of food, like the Kea parrot,
which attacks the sheep in New Zealand.
Some young woodpeckers are quite clever in opening fir cones to get at
the seeds, and this might be hastily referred to a well-defined
hereditary capacity. But the facts are that the parents bring their
young ones first the seeds themselves, then partly opened cones, and
then intact ones. There is an educative process, and so it is in scores
of cases.