Automatic detection and classification of nocturnal migrant bird calls

Abstract

Computer software was developed to detect the nocturnal flight calls of nine species of migrating warblers in digitized field recordings, and to classify the calls by species. The calls are frequency-modulated tones in the 5- to 9-kHz frequency band, and between 50 and 100 ms in duration. Detection was accompanied by locating temporal peaks in call band energy. Some false detections of insect calls were prevented by rejecting certain types of peaks. Classification is approached by tracking the frequencies of the calls over time and classifying the frequency tracks with an artificial neural network.