Definition of "wingbeat"

The birds spotted me the moment I approached. A strong southwest gale was blowing. At times, one or both of them would swing almost directly above me and without a single wingbeat remain almost motionless, in defiance of the wind, for moments at a time.

1961, Edmund C. Jaeger, Desert Wildlife, Stanford University Press, page 169

In addition to acoustic measurement, other methods can be used to determine wingbeat frequency.

2018, Robert Dudley, The Biomechanics of Insect Flight: Form, Function, Evolution, Princeton University Press, page 87