Ornis Hungarica. vol.10. (2000) p.65-70.
Individual recognition of corncrakes (Crex crex) by sound analysis
There are several species the monitoring data of which cannot easily be collected by any conventional technique (ringing, colour ringing, labelling, radio-tracking), although these data are essential for the study of these species' behaviour and ecological requirements. In this study we tested the method of individual recognition and investigated site fidelity of Corncrakes using their distinctive two syllable calls. Recordings were made in Szatmár- Bereg, NE Hungary, during the summer, 1999. We recorded all calling birds in the investigated meadow twice, the second recording was done ten days after the first one. Eleven calling males were recorded on the first field-survey and 12 on the second. For the individual recognition we measured the Euclidean distances between the discriminant function scores derived from the 15 variables measured on the waveform of the given individual's call. After ten days we found only one of the original eleven males calling in the same site of the same field using the stringent criterion for the individual recognition. In five cases values fell in an interval where, beside correct matches, a number of incorrect matches also can be made (lenient criterion). In conclusion we found at least 17 birds called in the study area. In the light of these findings, it would be advisable to survey other areas to acquire more precise information about the number, the site fidelity or the survival rate of corncrakes.