Craneworld - Resumés: 7.3 Resumé 2003: Acoustic individual monitoring over six years

The method; Experimental part

n the case of cranes, the "song" (the unison call) form is almost identical for all pairs with very subtle individual modulations, but varies qualitatively from species to species. The starting hypothesis for this work was that the frequency picture of the call should be determined by the length of the trachea, hence be relatively stable over time at least after the second or third year of life, and therefor be characteristic for an individual.

I developed a lightweight system consisting of a transportable minidisk recorder (various types supplied by Sony or JVC), fed by a long range microphone (Sennheiser MKH 70PH48 including an effective professional windshield) with highest sensitivity and resolution powered by an amplifier ("booster" Prefer Phantom), digital filing and two different computer based Fast Fourier Transformation analyses.

In the area where I developed the method (Hamburg), it is preferred to simply wait for the cranes to call. They do this relatively reliably in the morning up to 1 hours before sunrise, also often in the evening before sunset, and often during the day. As this area is easily accessible, I can combine a hike or other observation with recording. For this purpose, the recorder is on hold, and I react as quickly as possible as soon as I hear a crane calling.