Personality is widely observed in animals and has important ecological and evolutionary implications. In addition to being heritable, personality traits are also influenced by the environment. Population density commonly affects animal behavior, but the way in which it shapes animal personality remains largely unknown. In this study, we reared juvenile crayfish at different population densities and measured their personality traits (shyness, exploration, and aggression) after reaching sexual maturity. Our results showed repeatability for each behavior in all treatments, except for the shyness of females at medium density. There was a negative correlation between shyness and exploration in each treatment, and aggression and exploration were positively correlated in medium- and high-density females. These indicate the presence of a behavior syndrome. On average, the crayfish raised at higher population densities were less shy, more exploratory, and more aggressive. We found no behavioral differences between the sexes in crayfish. These results suggested that population density may affect the average values of behavioral traits rather than the occurrence of personality traits. Our study highlights the importance of considering population density as a factor influencing personality traits in animals and, therefore, might help us to understand animal personality development.

The Jiangsu coast located mid-way along the East Asian–Australasian Flyway, supports extensive natural mudflats that serve as critical stopover sites for millions of migratory waterbirds annually. However, diverse land uses—including wind farms, photovoltaic installations, fishing ports, and invasive Sporobolus alterniflorus—create potential conflicts between habitat suitability and human activity. This study integrates 11 environmental factors, including estuaries, fishing ports, wind power, photovoltaics, Spartina alterniflora, climatic conditions, and vegetation normalized difference indices, to comprehensively analyze the suitability of habitats for migratory waterbirds along the Jiangsu coast. According to species distribution models, the environmental factor that most significantly affects the habitat suitability for migratory waterbirds is Spartina alterniflora, followed by the distribution of fisheries, chemical factories, and estuaries. The main suitable distribution areas for migratory waterbirds in Jiangsu’s coastal region are located in the Yancheng Rare Bird Protection Zone, Dongtai Tiaozini Wetland, Lianyungang Linhong Estuary, Rudong Xiaoyangkou, and Dongling. Based on these findings, a multi-tiered management strategy is proposed: enhancing invasive species control and habitat restoration in core heritage zones; establishing ecological redlines and optimizing spatial planning to reduce fragmentation in developed areas; and creating localized wetland reserves with improved water-level management to maintain high-tide roosting function in scattered suitable habitats. We recommend integrating these spatial measures into provincial ecological planning to synergize wetland restoration with blue-carbon development, forming a coherent conservation network along the Jiangsu coast.

Understanding how avian assemblages respond to seasonal dynamics within urban land-cover structure is crucial for biodiversity conservation in rapidly urbanizing environments. Here, we investigated seasonal variation in avian dietary and foraging location guilds in central Taizhou City, China. Field surveys were conducted using the line transect method from April to November 2024. We assessed seasonal changes in community composition and the relationships between bird guilds and land cover types using multi-response permutation procedure (MRPP), non-metric multidimensional scaling (NMDS), and fourth-corner analysis. Bird community composition exhibited significant seasonal variations (MRPP, p < 0.05), with NMDS ordination showing a clear seasonal separation. Foraging location guilds exhibited more pronounced seasonal fluctuations in individual abundance than the dietary guilds. The Shannon diversity index for dietary guilds peaked in spring, followed by summer and autumn, whereas foraging location guilds exhibited higher diversity in summer and autumn. Fourth-corner analysis identified significant associations between guilds and land cover types, with foraging location guilds demonstrating stronger and more consistent responses to habitat structure than dietary guilds. Together, these results indicate that in urban landscapes, the spatial arrangement of habitats may shape avian foraging behavior more strongly than food availability alone, highlighting the need to integrate both structural and resource-based habitat features into urban planning and conservation.