Vocal Behaviors Of Common Kestrals (Falco Tinnunculus) In Breeding Season

The paper discusses the biological significations of main breeding calls of Common Kestrels(Falco tinnunculus) that occupied man-made nest boxes in Zuojia Reserve in Jilin province through acoustic analysis and behavior observation.Results show that all calls accord with birds' breeding behaviors and contain certain meanings.Spectrograms indicate all vocalizations have harmonic tones with inapparent basic sound(BS),and the frequency range of each kind of call is different form others,but hot range for all calls is from 1000Hz to 9000Hz.Power spectrums display that most sounds present distinct main power peak,and the main peak frequency(MPF) of various samples of sound sections(SS) mainly ranges between 3000Hz and 6000Hz,with about 4000Hz continually seen in spectrums.Moreover,the standard deviation(SD) of most acoustic parameters for each kind of call is large.The characters of spectrograms of normal calls include:the frequency bands(FB) are basically flat,and the pitch of calls is medium and more,higher for the end of each syllable. Hurried alert calls of which the shape of FB seems "∧" present higher pitch than other calls.The FB of slow worrying calls is flat and broken on the whole.Mating calls sound like worrying calls acoustically,but the former are more hurried and shriller than the latter. Food-delivering calls between two sexes,which can be in turn sorted four kind of calls named return-reminding calls,food-reminding calls,pre-delivering calls and delivering calls respectively,are a series of two kind of vocalizations.The result of vocalization compare between two breeding phases suggests the highest frequency(Hf) of alert calls is larger,which means more energy is paid out,than that of worrying calls in nestling-fostering phase.Contrarily,the Hf of worrying calls is higher than that of alert calls in hatching phase.It is thus concluded that the amount of energy paid out in singing is corresponding to breeding phase for Common Kestrels.Although vocalizations of males are similar to females acoustically,some acoustic parameters of same kind of call differ markedly between two sexes.Spectrograms of worrying calls of males show more upper partials(UP),higher lowest frequency(Lf),and power spectrums present larger MPF,than that of female,which demonstrates that males are better at singing than females in certain call for Common Kestrels.