Figure 1. Frequency histogram of call duration using all recorded caws from known individual American Crows. Duration was measured automatically using the internal 75% of the energy distribution of each call. This EDM duration measurement can be converted into a standard external measurement of duration by: standard duration (msec)  =  90 + 0.67(EDM duration in msec). Caws with a duration greater than 380 msec (n  =  70) are not shown on the histogram