Some birds

have feet of little power, and are therefore called
Apodes. This little bird is powerful on the wing; and, as a rule,
birds that resemble it are weak-footed and strong winged, such as
the swallow and the drepanis or (?) Alpine swift; for all these
birds resemble one another in their habits and in their plumage, and
may easily be mistaken one for another. (The apus is to be seen at all
seasons, but the drepanis only after rainy weather in summer; for this
is the time when it is seen and captured, though, as a general rule,
it is a rare bird.)