Results (1): identification of crane individuals / pairs
The basic questions for the individual recognition to begin with were (a) do the crane pairs call diferent enough to be differentiated? (b) do they call stable and reproducible enough to be recognised in later weeks and years?
Therefore, unison calls, with which Eurasian Cranes often begin the day even before dusk, were recorded in the morning, or in the evening, when defending their territory against other cranes, and during courtship. Also guard and flight calls, and also some other communication expressions were taken. In 1998, about 200 files from 7 pairs in their territories and outside of it, one adult unpaired male, and a few calls of unpaired youngsters, most of which were of analysable quality, had been recorded from late March to May.
The main result is that - although there are variations between the calls - the sonogram and the "voiceprint" for a given pairs are stable, reproducible and can be safely recognised by comparing the intensity maxima and minima at characteristic frequencies.