Change Of Song And Microgeographic Variation Of Dusky Warbler (Phylloscopus Fuscatus) In Breeding Season

As one of the most common ways of communication among songbirds,song plays an important role in all aspects of bird activities.Birds transmit more information through the change of song.Time,behavior,environmental change,geographical distance and so on will affect the song of birds.In order to reveal the song characteristics and changing rules of dusky warblers（Phylloscopus fuscatus）in reproductive period,this paper studied the song changes and geographical differences of male dusky warblers during reproductive period.Summer of 2016-2018,under sunny weather conditions,196 male dusky warblers were recorded in Saihanba,Hebei Province at 5:00 to 11:00 a.m.Daily used portable DR-600digital recorder（Tascam,Japan）and MKH416P48 strong directional microphone（Sennheiser Electronic,Germany）.In the Raven Pro Sound Analysis Software（Version 1.4,Raven,USA）,a clear and measurable linguistic chart was generated to measure the duration,the maximum frequency,the minimum frequency,the bandwidth,the peak frequency,the number of syllables and the characteristics of the syllables song by the dusky warbler.The results of statistical analysis on the song characteristics and changes of dusky warbler in different months and regions showed that:there were two sentence patterns in the song of the dusky warblers:S-song（Fig.2-7a）and V-song（Fig.2-7b）.And there were significant differences in the song output of S-song and V-song among months(ANCOVA:F_3,76=17.983,P<0.05;F_3,76=17.983,P<0.05;Table.3-2),with more S-song used than V-song in the whole breeding season.The output of S-song and V-song in each month showed the opposite trend:there were relatively more output of S-song in early（May）and late（August）breeding season,while more output of V-song in the middle breeding season（June）.There were significant difference in the maximum frequency,bandwidth and peak frequency(ANCOVA:F_3,76=4.841,P<0.05;F_3,76=3.814,P<0.05;F_3,76=3.793,P<0.05;Table.3-3)among months.Based on the 2 400 song verses from 80 males,65 syllable types were obtained（Fig.3-9）.More than 80%of the syllable types were used in all months（Fig.3-10）,but the number of syllable types used in each month were significantly varied(ANCOVA:F_3,76=5.456,P<0.05;Fig.3-11).The peak of syllable diversity was in July,with19.79±3.69 syllable types used,there were fewer syllable types in May and August,and the least in August.However,there were no significant difference in the frequency of S-song and V-song(F_5,84=1.169,P>0.05;F_5,84=1.169,P>0.05;Table.3-4)in the study of the differences in the vocal patterns of dusky warbler in six areas of Saihanba.There were no significant difference in the song sentences and trill of the maximum frequency(ANCOVA:F_5,84=1.772,P>0.05;F_5,84=2.026,P>0.05;Table.3-5,3-6),bandwidth(ANCOVA:F_5,84=2.173,P>0.05;F_5,84=1.993,P>0.05;Table.3-5,3-6),syllable number(ANCOVA:F_5,84=1.383,P>0.05;F_5,84=0.517,P>0.05;Table.3-5,3-6)and the peak frequency of trill(F_5,84=1.298,P>0.05;Table.3-6).But the duration of sentence and trill(F_5,84=7.705,P<0.05;F_5,84=4.396,P<0.05;Table.3-5,3-6),minimum frequency(F_5,84=6.932,P<0.05;F_5,84=2.653,P<0.05;Table.3-5,3-6)and sentence peak frequency(F_5,84=2.682,P<0.05;Table.3-5)were significant difference.The micro-geographical differences of the song were mainly reflected in the syllable types.Among the 99 syllable types classified in six regions（Fig.3-12）,the number of the syllable types by each individual is between 10 to 35,and the similarity coefficients of the syllable types among the six regions were significantly different（P=0.000;Fig.3-14）.The degree of syllable sharing between Qiancengban and Yangchang were the smallest（S_j=0.645;Table.3-8）;and between Sandaohekou and Sidaogou were the largest（S_j=0.871;Table.3-8）.The population of Saihanba dusky warblers had significant microgeographic differences in song.There were significant differences in the duration and the maximum frequency of song between normal and fallen tail feathers in dusky warblers（Z=-2.399,P=0.016;Z=-1.994,P=0.049;Table.3-10）,and the duration of song sentences,the number of syllables and the duration of trill are negatively correlated with the tail length（r=-0.579,P=0.002;r=-0.412,P=0.037;r=-0.455,P=0.019;Table.3-11）.The effect of tail feathers disappearance may be dealt with by increasing the length and the number of syllables of song sentences,that is,there was a compensation mechanism for tail feathers.