Diurnal Timing of Bird Surveys Using an Acoustic Monitoring System in the Shan-Ping Forest Ecological Garden

In this study, we report how to select the best timing of diurnal bird surveys when using an acoustic monitoring system. Although the system has been operating since March 2009 in the Shan-Ping Forest Ecological Garden, we transcribed only 2 morning recordings in the breeding season of 2009 due to the difficulty in transcribing recorded data. We found that the species accumulation curve reached a plateau (80%) in 30 min of the first hour and was higher than those in the latter 4 h on both days, which implied that the dawn chorus is the best period for recording bird sounds. A further analysis was used to locate the timing of the dawn chorus. The highest accumulation curve in a 10-min period appeared when the starting point was set at 5 min and 20 or 15 min before sunrise on March 31 and May 4, respectively. The difference revealed that the peak of singing activities occurred at different times over the breeding season. We suggest recording bird sounds for 1 h from dawn and selecting a sampling period of 10~20 min, which would cover most of the dawn chorus, to reach the highest species richness at the study site.