A second study [2] on the sandhill crane (grus canadiensis) was performed in order to evaluate individual and regional similarities and differences of their voice. Due to the use of the "guard calls" [3] and rather insensitive sonographical techniques (electromechanical, as available at that time), not only the recording method (a significant disturbance) was inappropriate for our goals, also the manual evaluation technique of the analogous sonograms is not effective. Moreover, the guard call was mostly expressed by the single crane in absence of its mate, so that pairs can not be identified, and hence the results of the study questionable. The unison call was not analysed by Weekly due to its complexity not manageable by this sonographical technique.