<b>The duration of urbanization influences </b><b>avian escape behaviour</b>

<b>Study area</b>Beijing City (39°26′-41°03′ N, 115°25′ -117°30′ E) is located in the northern part of the north China Plain, with a total administrative area of 16,410 km². It is surrounded by mountains in the west, north and northeast, and a plain to the southeast that slopes gently down to the Bohai Sea, with a warm temperate semi-humid and semi-arid monsoon climate. Considering the different time of construction and urbanization of different ring road areas in Beijing, as well as the influence of highways in Beijing on bird populations (Zhang <i>et al.</i>, 2013), the urban residential areas inside the Second Ring Road and outside the Fourth Ring Road, which have large differences in date of initiation of urbanization in Beijing, were selected in this study. The area within the Second Ring Road was defined as the old urban area, and the area outside the Fourth Ring Road was defined as the new urban area. All the residential areas studied are relatively closed and independent settlements with similar urban infrastructure (multi-story houses, concrete buildings, central squares, green spaces, gardens) and are surrounded by urban roads, green spaces, and buildings (Figure 1).Guangzhou City (22°26′-23°56′ N, 112°57′-114°3′ E), the capital of Guangdong Province, south China, is located in the Pearl River Delta, with a total administrative area of 7,334.4 km². Annual average temperature is between 21.7℃ and 23.1℃, with an average annual precipitation of 1,923 mm.Shenzhen City (22°24'-52' N, 113°43'-114°38' E) is located in the south of Guangdong Province, on the east coast of the Pearl River estuary, with a total administrative area of 1,997.47 km². It has a subtropical monsoon climate with mild temperatures and abundant precipitation, with an average annual temperature of 23.0°C. Shenzhen was founded in March 1979, and in August 1980 the Shenzhen Special Economic Zone was established. Over the past 40 years, Shenzhen has developed from a backward frontier town into a modern international metropolis. Considering the close geographic location between Shenzhen and Guangzhou Cities, and the difference in the duration of urbanization between them, in this study, Guangzhou was defined as an old city with a long history of urbanization and Shenzhen was defined as a neighboring new city.Xi'an City (33°39'-34°45' N, 107°40'-109°49' E) is located in the Guanzhong Basin, between the northern foot of the Qinling Mountains and Weihe River in north-western China, with a total administrative area of 10,108 km². Xi'an belongs to the warm temperate sub-humid continental monsoon climate, with a vegetation coverage rate of 29% (Xu <i>et al</i>., 2013). In this study, the area within the second ring road route of Xi'an City is defined as the old urban area, while the Economic and Technological Development Zone, Qujiang New District and Chanba Ecological Zone are defined as the new urban area.<br><b>Study species</b>Birds living in cities are more susceptible to anthropogenic activities and then are more likely to change their behavior to adapt to urban environment. About 10,000 years ago, the Eurasian tree sparrow (<i>Passer montanus</i>) had already adapted to the human environment of the time and were closely connected with human society (Sætre <i>et al.</i>, 2012). As one of the earliest organisms associated with human urban life (Møller, 2015), Eurasian tree sparrows mainly feed on the ground and often use the food resources in the city. As the dominant species in the city, they are an ideal subject for studying the adaptability of birds to urbanization. In addition, commonly seen ground-foraging birds in urban areas, including the Chinese blackbird (<i>Turdus mandarinus</i>), spotted dove (<i>Spilopelia chinensis</i>) and azure-winged magpie (<i>Cyanopica cyanus</i>), were also selected in this study, which are distributed in urban and rural environments throughout China (Zheng, 2023).In this study, four areas in Beijing, Xi'an, Guangzhou and Shenzhen with significant differences in initiation of urbanization were selected as study sites, and flight initiation distance (FID) was observed for common ground-foraging birds in these cities. The results showed that the duration of urbanization significantly affected the adaptation of birds to anthropogenic disturbance in cities. Birds living in areas with longer periods of urbanization were more tolerant to anthropogenic disturbance. Our study suggests that the duration of urbanization has an important influence on the behavioral adaptation of birds to human disturbance.