Apparently only swallows were suspected to hibernate, and even in ancient Greece, people knew about bird migration. The swallow hibernation theory was described

Apparently only swallows were suspected to hibernate, and even in ancient Greece, people knew about bird migration. The swallow hibernation theory was described as disproved before the 18th century: https://en.wikipedia.org/wiki/Bird_migration#Historical_views https://en.wikipedia.org/wiki/Bird_migration#Historical_view...