Invasive smooth cordgrass (Spartina alterniflora) has been expanding rapidly through the coastal wetlands of eastern China and these changes negatively affect local birds. In the Dafeng Milu National Nature Reserve (henceforth referred to as DMNNR), rapid degradation of spartina occurs after an increase in milu (Elaphures davidianus; hereafter elk) numbers and ecological hydrological engineering. We evaluated the impact of such degradation on the abundance and species diversity of birds in the DMNNR during 2017–2021. We found that the area covered by S. alterniflora decreased significantly in the study area at a rate of 310 ha per year and by 62% during 2017–2021 (p < 0.01). With this decrease in the S. alterniflora area, the species richness and abundance of birds first increased and then decreased. Songbird density clearly decreased but species richness did not significantly do so. This research demonstrated that during the initial stages of vegetation degradation, there was a positive effect on bird diversity. With the increasing vegetation degradation increases, both songbirds and waterbirds experience negative impacts. The DMNNR is an important stopover site for waterbirds in the East Asian–Australasian Flyway, and additional measures are needed to control vegetation degradation and to restore the native habitats for birds.

After the smooth cordgrass Spartina alterniflora invaded coastal China, native birds started avoiding the green desert, and bird diversity declined. After many years, a few passerine birds began to enter and use smooth cordgrass, but only birds with a nonspecialised habitat. In this study, we found that a native reed‐specific bird, the parrotbill Calamornis heudei, flocked and sang in a smooth cordgrass habitat throughout the overwintering period near Sheyang Port in Yancheng, Jiangsu Province. This observation suggests that native obligate birds may be forced to adapt to exotic smooth cordgrass habitats after long‐term coexistence, which would, obviously, affect the distribution, feeding and reproduction of birds. The concern is that this could be an ecological trap, leading to unknown consequences. More research is required to examine the process occurring along the Chinese coast.

The mitochondrial genome of Paradoxornis heudei is described in this study. The molecule is 16,924 bp in length and contains 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and an AT-rich region. All PCGs use the typical start and stop codons, except COX3, ND2, and ND4 use T or TA as their stop codons. The rrnL and rrnS genes are 1602 bp and 984 bp in length, respectively. Phylogenetic analysis shows that the least evolved Paradoxornis locates at the basic position of Muscicapidae and among Paradoxornis, the other three species are firstly clustered together, then constitute a monophyletic group with P. heudei.

In anurans, the complexity of courtship calls may affect female mate choice. The current study suggests that nonlinear phenomena (NLP) components can contribute to increasing complexity in courtship calls and attracting female attention. The results of a recent study showed that calls of large odorous frog (Odorrana graminea) contained NLP components. However, whether the nonlinear components of courtship calls in O. graminea improve male attractiveness remains unknown. We hypothesized that female O. graminea would prefer males producing calls with a higher proportion of NLP components (P‐NLP‐C). To test this hypothesis, we recorded the advertisement calls of 28 males and confirmed that the P‐NLP‐C was significantly positively related to body size. We also measured the body size of natural amplectant males and non‐amplectant males in the field and found that amplectant males had larger body sizes than non‐amplectant males, and the results of two‐choice amplexus experiments similarly revealed a female preference for males with larger body sizes. Additionally, phonotaxis experiments also revealed that females preferred male calls with a high P‐NLP‐C. The results suggest that a higher P‐NLP‐C in calls can enhance male attractiveness, and the P‐NLP‐C may provide key information about male body conditions for female O. graminea. Our study provides a new insight for better understanding the role of NLP in anuran mate selection.