All tame animals are much more subject to disease than wild ones; and
birds so much the more, as they are often shut up in very small cages,
where they can take no exercise. It is often supposed that birds, in
their natural free state, have no diseases; but people who will take the
trouble to observe, will soon perceive the falsehood of this assertion.
I have often found hedge-sparrows full of pimples, particularly in the
naked parts, the feet, and round the beak. Their diseases are often
increased by the delicacies of all kinds which are given them, such as
biscuits and sugar, which injure the stomach, and cause a slow decay.
The principal diseases and their cures, according to my experience, are
as follows; not, however, that different birds do not require, according
to their food, different treatment.
I shall mention, under each bird, what must be done to cure those
diseases which are peculiar to it, when general remedies fail.