Roepactiviteit van een Kwartelkoning Crex crex gedurende opkomend en weer verwaaiend onweer

On the warm afternoon of 29 June 2010 protocols were made of a calling male Corn Crake between 13:30 and 17:15 h. The weather was warm (probably above 26.9°C). Initially the weather was sunny and calm, but around 14:00 there was a short wave of strong wind. From 14:30 the weather became increasingly instable and at 14:50 windspeed again increased. The sky in the north turned darker. Around 15:00 it was sultry and the thunderstorm seemed to be very near. At 15:30 the sky became lighter and at 15:40 fell some drops of rain. Between 15:50 and 15:54 there was an intense short shower and between 16:14 and 16:20 it rained a little. The Corn Crake called almost continuously during the observation period with a slightly moderating frequency in producing calling sessions. The number of calls (“crex-crex”) however sharply increased around 15:00, when temperature was still high and the atmosphere was most sultry (Figure 1). After the first rain sessions became shorter, but occurred with short intervals between them, resulting in a still high number per 15 minutes. Later the calling intensity decreased.