Reedbeds are crucial breeding habitats for vulnerable songbird species. Irrespective of their protection status, these habitats may be threatened by organic matter accumulation, progressively leading to structural homogenization and habitat succession towards woodland. Managers prevent excessive litter build-up with various interventions opening-up the reedbeds, such as grazing, which may be detrimental or suitable for some reed bird species. We assessed the effects of extensive grazing by horses and its cessation in the medium and long terms on reedbed structure, and the consequences on reed-nesting songbird densities in Estagnol Nature Reserve, a protected wetland near the French Mediterranean coast. We compared reedbed structural features between grazed, newly ungrazed and old-ungrazed plots. During nine years, we censused four songbird species in spring and collected water level data in the same survey plots. Grazing reduced reedbed extent, rejuvenated the vegetation with more short green stems on a thinner litter, and produced higher structural heterogeneity and discontinuity compared to long-lasting non grazing. Newly ungrazed plot showed intermediate effects. All surveyed songbird total densities were similar among plots while species numbers and densities differed. Grazed reedbed was more attractive to Moustached Warblers (Acrocephalus melanopogon) and Great Reed Warblers (Acrocephalus arundinaceus), likely due to the large edges and the high vegetation structural heterogeneity. However, Moustached Warblers were more negatively affected by higher water level in grazed reedbed, presumably because flooding prevents litter foraging. The newly ungrazed reedbed was not preferred by any species. All warbler species were found under low density in the old-ungrazed reedbed, where Reed Buntings (Emberiza schoeniclus) were exclusively found. Food availability related to thick litter layer may explain this predilection. Common Reed Warblers (Acrocephalus scirpaceus) were found everywhere in similar densities. We conclude that reedbed management by extensive horse grazing and also its long-term cessation may benefit several songbird species. Within a context of wetland degradation and disappearance, both management strategies are useful to establish and maintain suitable habitats for reed-nesting songbird communities.

For migratory waterbirds, the quality of wintering habitat is related to spring migration and successful breeding in the next year. The availability of food resources in the habitat is critical and varies within water levels. Although the water-level fluctuations in Poyang Lake have been extremely variable interannually in recent years, the wintering waterbird populations have remained relatively stable. Hence, the mechanism of maintaining the stability is worth exploring. This study aimed to compare the distribution of vegetation and herbivorous waterbirds in 2015–2016 and 2016–2017, focusing on three shallow sub-lakes and one main lake are. The results showed that the emergence of tubers and the growth of Carex spp. provided a continuous food supply and habitat for wintering waterbirds with a gradual decline in the water level. Shallow sub-lakes supported almost all of the tuber-eating waterbirds (1.42–1.62 × 105) and most geese (1.34–1.53 × 106). However, the main lake area, covered with Persicaria hydropiper, did not provide adequate and accessible food. This resulted in almost no distribution of tuber-eating waterbirds, with only a few geese congregating in early winter. Our results demonstrated that the shallow sub-lakes under human control provided a different environment from the main lake and are key to sustaining the successful wintering of hundreds of thousands of migratory waterbirds in Poyang Lake. Therefore, we recommend refining the anthropogenic management of the shallow sub-lakes to regulate the water level to ensure the carrying capacity of Poyang Lake.

Weather conditions play a pivotal role in embryo development and parental incubation costs, potentially impacting the clutch size and incubation behavior of birds. Understanding these effects is crucial for bird conservation. Reeves's Pheasant (Syrmaticus reevesii) is a threatened species endemic to China, which is characterized by female-only incubation. However, there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this species. Using satellite tracking, we tracked 27 wild female Reeves's Pheasants from 2020 to 2023 in Hubei Province, China. We explored their clutch size and incubation behavior, as well as their responses to ambient temperature and precipitation. Clutch size averaged 7.75 ± 1.36, had an association with average ambient temperature and average daily precipitation during the egg-laying period, and was potentially linked to female breeding attempts. Throughout the incubation period, females took an average of 0.73 ± 0.46 recesses every 24 h, with an average recess duration of 100.80 ± 73.37 min and an average nest attendance of 92.98 ± 5.27%. They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:00. Furthermore, females rarely left nests when daily precipitation was high. Recess duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation, as well as day of incubation. Additionally, there was a positive correlation between clutch size and recess duration. These results contribute valuable insights into the life-history features of this endangered species.

Understanding the foraging behavior is essential for investigating seabird ecology and conservation, as well as monitoring the well-being of the marine environment. Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance. Such trade-off may stem from the heterogeneity of food resources and the constraints of central place foraging. Nevertheless, abundant marine productivity could alleviate the energy limitation for seabirds, resulting in a consistent foraging approach. Here, we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird, Swinhoe's Storm-petrel (Hydrobates monorhis), in the Yellow Sea, a productive marginal sea of the Northwest Pacific. Using GPS tracking, we evaluated habitat preference, quantified the foraging strategy, and tested if environmental conditions and individual traits influence foraging trips. We found that Swinhoe's Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips. Distinctive southeastward and southwestward strategies emerged when combining trip metrics, including foraging direction, duration, and maximum distance. The bathymetry, proximity to the coastline, and sea surface temperature differed in two foraging strategies. Foraging strategies exhibited flexibility between individuals, potentially explained by wing morphology, in which longer-winged birds are more likely to embark on longer-distance foraging trips. These findings highlight the impact of environmental factors and individual traits on seabirds' foraging decisions in productive marginal sea ecosystems. Our study also provides valuable insights into the foraging ecology of this Asian endemic storm-petrel.

With continually increasing urbanization, the land cover in urban areas continues to change, resulting in the loss of biodiversity. Birds are highly sensitive to changes in habitat. Most forest birds perch on plants that provide increased safety to reduce the risk of predation, and small birds may also consider insulation when using roosting plants in winter because of cold weather. Landscaping plants thus shape the nocturnal roosting environment of urban birds, and proper planting is essential for the survival of birds at night. The use of roosting plants by urban birds should therefore be studied to provide a reference for landscaping. In the current study, we observed 1865 nocturnal roosting birds in Beijing from 2021 to 2022, with 23 species of birds from 12 families and 45 species of plants from 22 families recorded. Juniperus chinensis exhibited the highest bird rarity-weighted richness, followed by Fraxinus pennsylvanica, Phyllostachys propinqua, Pinus tabuliformis, and Ulmus pumila. The diameter at breast height, tree height, and crown width of plants used by birds was largest in summer and smallest in winter, and the perch height of birds was the highest in spring and summer and the lowest in winter. Birds used the highest proportion of deciduous plants in summer and the highest proportion of evergreen plants in winter. A significant seasonal difference in the use of evergreen and deciduous plants by small birds was noted, with a preference for deciduous plants in summer and evergreen plants in winter, while this preference was not found in large birds. These findings indicate that evergreen plants provide a vital nocturnal roosting environment for small birds in winter. To provide a better nocturnal roosting habitat for urban birds, we recommend paying attention to the combination of evergreen and deciduous plants when carrying out landscape construction.

Avian interspecific brood parasitism is an excellent system for studying coevolutionary processes in nature because brood parasites directly affect host reproductive success. Most research on avian brood parasitism has, therefore, focused primarily on specific host anti-parasite behaviours and parasite counter-adaptations. However, the population-level consequences of brood parasitism for host species are poorly understood. This study investigated the effect of Common Cuckoo (Cuculus canorus) parasitism on the productivity of a local population of the Great Reed Warbler (Acrocephalus arundinaceus) host in south-western Slovakia. A total of 495 females nesting at the studied site successfully fledged 1321 of their own young and 63 young of the Common Cuckoo over the course of 15 years (2008–2022), and the annual rate of successful parasitism ranged from 18% to 44% over this period. As predicted, higher rates of successful cuckoo parasitism significantly reduced the annual productivity of the local Great Reed Warbler population, and its contribution to decreased host reproductive success was at about the same rate as overall nest failure caused by predation and other environmental factors. Such a heavily parasitized population was probably maintained by immigrants from other populations and density-dependent selection, which is also consistent with source–sink dynamics. However, further long-term studies monitoring parasitized populations are required to confirm these findings.

In many songbird species, birdsong features phonological syntax, meaning that the units within their vocal sequences are ordered in a non-random way that adheres to a rule. While such syntactical patterns have been richly described in many species, comparatively little is known about how those patterns contribute to song achieving its important functions. For each of song's main functions, territorial defense and mate attraction, evidence of a role for syntax is limited. One species for which syntax has been thoroughly described is the Hermit Thrush (Catharus guttatus), which presents song types from their repertoires in a semi-predictable order and, in doing so, rapidly cycle up and down the frequency spectrum. The objective of the present study was to explore the importance of song syntax in the Hermit Thrush through a within-subject examination of how measures of syntax, such as the predictability of song type order within song sequences, shift over the breeding season. We hypothesized that, if such syntactical characteristics are important to breeding behaviour, they would be most prominent at the start of the breeding season when activity associated with territory establishment and mate attraction is most intense. Analysis revealed that, as predicted, the rigidness of song type ordering within sequences was highest at the start of the season and declined thereafter. That song type sequences were most predictable at the vitally important early part of the breeding season fit our hypothesis that this aspect of song syntax is important to song's functions related to territory establishment and/or mate attraction. Future work will clarify whether that role relates to one of song's two main functions or serves song transmission in some broader way.

Rivers are important habitats for wintering waterbirds. However, they are easily influenced by natural and human activities. An important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal behavior. The compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time, which in turn increases food intake and helps maintain a constant energy balance. However, it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or foraging. In this study, the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck (Anas poecilorhyncha) in two rivers in the Xin'an River Basin from October 2021 to March 2022. The allocation of time and energy expenditure for activity in both normal and disturbed environments was calculated. The results showed that foraging accounted for the highest percentage of time and energy expenditure. Additionally, foraging decreased in the disturbed environment than that in the normal environment. Resting behavior showed the opposite trend, while other behaviors were similar in both environments. The total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment, with decreased foraging and resting time percentage and increased behaviors related to immediate safety (swimming and alert) and comfort. These results oppose the compensatory foraging hypothesis in favor of increased security. The optimal diurnal energy expenditure model included river width and water depth, which had a positive relationship; an increase in either of these two factors resulted in an increase in energy expenditure. This study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental conditions. Exploring these changes can help understand the maximum fitness of wintering waterbirds in response to nature and human influences.

Biological specimens are fundamental for taxonomy and flora/fauna research. More importantly, they also play crucial roles in recording environmental impacts on morphology and behavior, which is vital for biodiversity research and conservation. However, there are few systematic studies on the patterns and drivers of bird specimen number at regional scales. This study is the first attempt to examine the relationships between bird specimen number and species traits as well as climate niche breadth in China, aiming to answer two questions: 1) how do species’ temperature niche breadth and precipitation niche breadth influence specimen number? 2) which trait is most associated with bird specimen number? The associations between bird specimen number and explanatory variables were examined using ordinary least squares, generalized linear models, phylogenetic generalized linear mixed models, and multiple comparisons. The results showed that Muscicapidae was the family with the highest specimen number, and Passeriformes was the order with the highest specimen number. Bird specimen number significantly increased with larger temperature niche breadth and precipitation niche breadth. Specimen number was also positively associated with geographic range size, habitat specificity, hunting vulnerability and clutch size, but negatively associated with body size. These findings suggest that future bird specimen collection should pay more attention to birds with limited ecological niches, large body sizes, and small clutch sizes. This research enhances the use of bird specimen data to study and preserve biodiversity.

Due to a complex geological and biotic history, the Isthmus of Tehuantepec (IT), has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa. Widely distributed in the lowlands of the American continent, the White-Tipped Dove (Leptotila verreauxi) is a polytypic species with 13 recognized subspecies. Four of these have been recorded in Mexico, and the distribution of three abuts at the IT, suggesting a contact zone. To estimate phylogenetic patterns, divergence times and genetic differentiation, we examined two mtDNA (ND2 and COI) and one nDNA (β-fibint 7) markers. We also used correlative ecological niche models (ENM) to assess whether ecological differences across the IT may have acted as a biogeographical boundary. We estimated paleodistributions during the Middle Holocene, Last Glacial Maximum and Last Interglacial, to evaluate the influence of climate changes on the distribution and demographic changes. Our results showed genetically distinct lineages that diverged approximately 2.5 million years ago. Climatic and ecological factors may have played a dual role in promoting differentiation, but also in the formation of a secondary contact zone in the southern IT. Our ecological niche comparisons indicated that the ecological niche of sympatric lineages at the IT are not identical, suggesting niches divergence; in addition, environmental niche models across the region indicated no abrupt biogeographic barriers, but the presence of regions with low suitability. These results suggest that genetic differentiation originated by a vicariant event probably related to environmental factors, favored the evolution of different ecological niches. Also, the absence of a biogeographic barrier but the presence of less suitable areas in the contact regions, suggest that secondary contact zones may be also maintained by climatic factors for the eastern group, but also by biotic interactions for the western group.