Changes Of The Body Size,Body Condition Levels And Song Of Tree Sparrows (Passer Montanus) Along The Urbanization Gradient

Bird,an important part of urban ecosystem,are closely related to human beings and served as an indicator for environmental changes.With the rapid development of economy in the past several decades in China,the process of urbanization is accelerating,which resulted in prominent problems of urban environment.The impacts of urbanization on birds has attracted extensive attention from ecologists and wildlife conservationists.With the accelerating urbanization,the natural habitat in the city decreases,which leads to the decrease of the environment and natural food suitable for the survival of birds,thus affecting the survival and health of birds.The individual's survival health is usually reflected by body shape and physical fitness level.In cities,the ambient noise level increases significantly,and the noise will mask the birds' acoustic signals,which will undoubtedly affect the song communication between birds.Taking the tree sparrow(Passer montanus)as the research object,this study selected six study sites under different urbanization levels in Shenyang,and studied the physical characteristics of adult male tree sparrows under different urbanization levels in the urban and suburban areas of Shenyang,and the relationship between physical characteristics and urbanization levels.In addition,the effects of urban environmental noise on tree sparrows' singing behavior were studied,and the singing characteristics of tree sparrows in the breeding period under different noise levels were compared between the urban and suburban areas of Shenyang,as well as the relationship between the singing characteristics and noise levels.The main results of this study were as follows:1.The tarsus length,middle toe length,and body length of tree sparrow in urban area were significantly higher than those in suburban area(all P < 0.05).There was no significant difference in body mass index and other parameters of physical signs between urban and suburban areas(both P > 0.05).Based on the principal component analysis of 9 physical signs of tree sparrow,the cumulative contribution rate of 5principal components reached 79.672%,which indicated that these 5 principal components summarized most of the index information.The contribution rate of the first principal component was 28.265%,in which the absolute values of body length,middle toe length and hind toe length were relatively high.The contribution rate of the second principal component was 18.304%,and the absolute values of wing length and body weight were higher.The contribution rate of the third principal component was 14.162%,and the absolute values of beak width and beak length were higher.The contribution rate of the fourth principal component is 9.602%,and the absolute value of the load of tarsus length is higher.The contribution rate of the fifth principal component was 9.339%,in which the absolute value of the load of body weight was higher.There was no significant correlation between the body mass index(BMI)and the five principal components of tree sparrow and the urbanization level(P > 0.05).2.The noise level in urban areas was significantly higher than that in suburban areas(P < 0.01).In the urban areas,the highest frequency,bandwidth,and main peak frequency of tree sparrow songs were significantly higher than those in suburban areas(all P < 0.01),and the lowest frequency was significantly higher than that in quiet suburbs(P < 0.05),while the duration had no significant difference(P > 0.05).The highest frequency,bandwidth,peak frequency and duration of tree sparrow songs were not correlated with the noise level(all P > 0.05).The lowest frequency was significantly positively correlated with the noise level(P < 0.01).With the increases of noise level,the lowest frequency of song decreased.In conclusion,tarsus length,middle toe length,and body length of the tree sparrow increased significantly along the urbanization gradient,which indicated that body size of tree sparrow are becoming larger.There was no significant decrease of the tree sparrows' body mass index and other physical parameters such as body weight,beak length,beak width,hind toe length,wing length and tail length,indicating that the urban environment did not have a negative impact on the tree sparrow.The songs of tree sparrows had significantly higher maximum frequency,higher minimum frequency,wider bandwidth,and higher peak frequency in urban environment.There was a significant positive correlation between the lowest frequency and the noise level,which indicated that the tree sparrow could adjust to the environmental noise by increasing the lowest frequency.