Measurements of the force generated by the legs of rock doves Columba livia during vertical and near-vertical take-off showed that the birds were able to develop an upward directed force of from 1.3 to 2.3 times their body weight. This force resulted in an instantaneous acceleration of 15.63 ms−2 at maximum thrust. Motion pictures taken during the take-off showed that as the birds' feet left the experimental perch, their wings were in the overhead clap position. We suggest that the vertical take-off in birds is accomplished in three stages; leg thrust, clap-and-fling and steady-state flight.

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