Which Leonardo da Vinci notebook is devoted mainly to his studies of bird flight?

The Codex on the Flight of Birds is Leonardo da Vinci’s notebook devoted mainly to bird flight and flying machines.

Leonardo compiled the manuscript in 1505 in the Italian town of Vigevano. It contains observations of birds, notes on air currents, and designs for devices intended to imitate or exploit natural flight. The notebook shows how his inventions grew from close study of anatomy and movement.

The codex is particularly important because it connects biological observation with engineering. Leonardo examined how birds used their wings and tails, then considered whether a human-made machine could reproduce those actions. His reasoning was exploratory, and several proposals remained impractical because human muscle could not supply enough power.

The notebook should not be confused with the much larger Codex Atlanticus, which contains material on many subjects. The Codex on the Flight of Birds is a more focused source for Leonardo’s aviation studies.