Large-scale agricultural development has led to a significant reduction in wetland areas, resulting in habitat fragmentation for birds and biodiversity loss. Recently, the implementation of farmland abandonment policies has helped in the restoration of wetland areas. In order to understand the ecological effects of farmland abandonment, this study investigated the bird communities in the Naoli River National Nature Reserve (NRNNR) in the Sanjiang Plain after abandonment. The field surveys (line transect and point count methods) of bird community diversity in the abandoned areas of the NRNNR showed 92 bird species from 37 families and 16 orders, including 4 species of national first-class protected birds and 17 species of national second-class protected birds (accounting for a combined 22.83%). Additionally, the bird community diversity displayed annual variation in individual and species richness over time, and the diversity indices order was 2019 > 2020 > 2018 > 2016 > 2015. Bird species richness and individual abundance were significantly higher in meadow habitats as compared to other habitat types. With prolonged restoration time after farmland withdrawal, the Pielou evenness index of bird communities significantly decreased, while the total number of individual birds significantly increased (p < 0.05). The abandoned time showed a positive impact on waterbird richness, while the longer abandoned duration led to higher waterbird richness. In conclusion, long-term ecological restoration measures revealed a significant enhancement in bird diversity over time.

This study was designed to determine the fragmentation of sub-lakes in winter and its effects on wintering waterbirds in Poyang Lake. Poyang Lake becomes fragmented in winter, which forms many seasonal sub-lakes every year, and have different environmental characteristics. These sub-lakes significantly impact winter bird habitats and result in susceptibility to various changes, because birds have different distribution responses. A total of 24 sub-lakes were surveyed from one to five vantage points using point count methods in each sub-lake with binoculars, monocular, and a spotting scope for four consecutive winter seasons. The multi-site dissimilarity Sorensen index measures overlapped between two populations, and the R software “iNEXT” package was used to evaluate the sample coverage test of the study area. We observed 58 wintering waterbird species belonging to 9 orders and 15 families from 2016 to 2020. Spearman correlation analysis showed that the species richness of wintering waterbirds was significantly positively correlated with the sub-lake areas and associated with the richness of habitat type. The WNODF analyses were considerably correlated for sites of waterbirds, mainly with the abundance of forage and conservation of habitat form. The outcomes of this study showed that Maying Lake has the highest local beta diversity, whereas Dacha Lake has the lowest local beta diversity contribution (0.007). This study’s findings demonstrate Poyang Lake’s role in waterbird the habitat suitability of waterbirds, especially for foraging and conservation.

The red-crowned crane (Grus japonensis) is a flagship species for wetland biodiversity in East Asia. The Songnen Plain is a vital wetland and habitat for rare and endangered birds in Northeast China. However, rapid land use changes have raised urgent concerns about habitat loss and the survival of these populations. We combined 30 years (1990–2020) of field surveys with ensemble species distribution models (SDMs) to analyze the spatio-temporal changes in suitable habitats for all three key life stages—spring migration, breeding, and autumn migration—across the Songnen Plain. We also assessed how well the current protected-area (PA) network covers suitable habitats and identified conservation gaps. Land use type was the most significant predictor of habitat suitability. Over this period, suitable habitats decreased sharply by 60% (spring migration), 72% (breeding), and 76% (autumn migration), with severe fragmentation and a clear northward shift. Core suitable areas are now mainly found within a few nature reserves, including Zhalong, Wuyu’er River, and Xianghai. We identified three significant conservation gaps: Lindian–Anda, Tailai–Dumeng, and Meilisi Daur–Fuyu. Our results show widespread habitat reduction and demonstrate the inadequacy of the current PA network in supporting the long-term survival of red-crowned crane populations. We recommend expanding protections and restoring wetland connectivity within these gaps to maintain critical habitats and improve landscape resilience for this endangered species.

The continuous advancement of urbanization and the expansion of cities inevitably have certain impacts on urban wildlife. Birds are a highly visible group of urban wildlife, widely distributed and sensitive to environmental changes. Birds’ song is an important way of conveying information; the effective conveyance and transmission of bird songs are crucial for attracting mates and successful reproduction. However, the impact of urban development on the songs of many birds remains unknown. This study compared the differences in song characteristics (maximum frequency, minimum frequency, main frequency, and duration) of the Eurasian Nuthatch (Sitta europaea) at six different research sites with different levels of urbanization, in order to explore the song response patterns of birds to urbanization. The results indicate that urbanization leads to a reduction in avian song diversity and a convergence in song parameters. Birds in different life history stages show inconsistent responses to urbanization. During the overwintering period, there are no significant differences in the minimum frequency and duration of the Eurasian Nuthatch’s song, almost no significant differences in the maximum frequency, and the main frequency of the Eurasian Nuthatch’s song, as distributed in the Forest Botanical Garden (FBG) shows some differences compared to other study sites. During the breeding period, there are no significant differences in the main frequency of the Eurasian Nuthatch’s song, while other parameters exhibit varying degrees of differences. Comprehensive analysis reveals that urbanization has varying impacts on the song diversity of the Eurasian Nuthatch across different life history stages. During the overwintering period, there is a significant reduction in song diversity, with a pronounced homogenization effect; during the breeding period, the birds’ songs are more diverse, with only the main frequency showing a significant homogenization effect. It is speculated that birds may strike a certain balance between adapting to urbanization and survival reproduction.