Avian Research最新文献

Beta diversity, the variation of community composition among sites, bridges alpha and gamma diversity and can reveal the mechanisms of community assembly through applying distance-decay models and/or partitioning beta diversity into turnover and nestedness components from functional and phylogenetic perspectives. Mountains as the most natural experiment system provide good opportunities for exploring beta diversity patterns and the underlying ecological processes. Here, we simultaneously consider distance-decay models and multiple dimensions of beta diversity to examine spatial variations of bird communities, and to evaluate the relative importance of niche-based and neutral community assembly mechanisms along a 3600-m elevational gradient in the central Himalayas, China. Our results showed that species turnover dominates taxonomic, functional, and phylogenetic beta diversity. We observed strongest evidence of spatial distance decays in taxonomic similarities of birds, followed by its phylogenetic and functional analogues. Turnover component was highest in taxonomic beta diversity, while nestedness component was highest in functional beta diversity. Further, all correlations of assemblage similarity with climatic distance were higher than that with spatial distances. Standardized values of overall taxonomic, functional, and phylogenetic beta diversity and their turnover components increase with increasing elevational distance, while the standardized values of taxonomic and phylogenetic nestedness decreased with increasing elevational distance. Our results highlighted the niche-based deterministic processes in shaping elevational bird diversity patterns that were determined by the relative roles of decreasing trend of environmental filtering and increasing trend of limiting similarity along elevation distances.

Management under ecological schemes and increasing habitat heterogeneity, are essential for enhancing biodiversity in vineyards. Birds provide several contributions to agriculture, for example pest control, recreation and enhancing human mental health, and have intrinsic value. Birds are also ideal model organisms because they are easy to survey, and species respond differently to agricultural land use at different scales. Vegetated borders of crops are key for many species of birds, and distance to the border have been found to be an important factor in vineyard-dominated agroecosystems. We evaluate if there are differences in the bird assemblage, between the interior compared to borders within vineyards, using a hierarchical community occupancy model. We hypothesized that occupancy of birds is greater in environments with greater heterogeneity, which in this study was considered to be contributed by the proximity to vegetated corridors. We expected that vineyard borders close to corridors will have higher bird occupancy than the center of the vineyard. The research was conducted in three vineyards with biodiversity-friendly management practices, in Gualtallary, Mendoza, Argentina. Bird surveys were conducted over three breeding seasons from 2018 to 2020. Occupancy and richness of the bird community was more closely associated with the borders adjacent to the corridors than with the interior of the vineyards, as we initially predicted, although the assemblage of birds did not differ much. More than 75% of the registered species consume exclusively or partially invertebrates. Biodiversity-friendly management and ecological schemes, together with vegetated corridors provide multiple benefits for biodiversity conservation. These approaches not only minimize the use of agrochemicals but also prioritize soil cover with spontaneous vegetation, which supports a diverse community of insectivorous bird species, potentially contributing to pest control.

Nests are important structures for birds to raise their offspring and for signaling. Many birds incorporate feathers into the nest, since feathers were traditionally thought to serve the function of insulation. Hypotheses in recent years have considered that some birds place feathers in conspicuous locations in the nest for decoration to trigger a fear response in the competitors. In this study, we investigated whether decorative feathers could deter nest usurpation by Crested Mynas (Acridotheres cristatellus) by manipulating nest box contents. The results revealed that Crested Mynas preferred black feathers to white feathers as decorations and occupied nest boxes decorated with black feathers significantly less than those decorated with white feathers, suggesting that black decorative feathers in the nest could be more effective in preventing nest usurpation by Crested Mynas and that white decorative feathers may have other functions. The black feathers in the nest are prominently placed at the edge of the nest to convey the message that “this nest is occupied” or “the owner of this nest has been preyed upon” to visitor Crested Mynas, thus effectively preventing them from usurping the nest at a later stage.

Extreme droughts are increasing in frequency and severity globally as a result of climate change. Developing understanding of species' responses to drought is crucial for their conservation, especially in regions experiencing increased aridity. Although numerous studies have investigated birds' responses to drought, the emphasis has primarily been on landbirds. Drought can significantly alter the wetland environments that waterbirds inhabit, but the response of waterbirds to drought remains understudied. In this study, we surveyed the distribution and behavior of Oriental Storks (Ciconia boyciana) in Poyang Lake, which is the largest freshwater lake in China. Results indicate that drought-induced catchment areas at the lowest water level limited the total population size of Oriental Storks in the sub-lakes. Sub-lakes with large catchment areas at the lowest water level demonstrated a capacity to support a larger population of wintering Oriental Storks. Over time, Oriental Storks exhibited a gradual concentration in Changhu Lake, characterized by larger catchments, after resource depletion in sub-lakes with smaller catchments. Additionally, the duration of Oriental Storks’ vigilance and moving behaviors decreased significantly compared with that observed before the drought. After the drought, Oriental Storks increased their foraging efforts, as evidenced by increased presence in deeper water and reaching their heads and necks into deeper water to forage, higher search rates, but lower foraging rates. In accordance with area-restricted search theory, reductions in habitat quality resulting from drought, including extensive fish die-offs, forced Oriental Storks to increase their foraging efforts. Sustaining a specific water area in sub-lakes during droughts can preserve resource availability, which is crucial for the conservation of Oriental Storks. Implementing measures such as water level control and micro-modification of lake bottoms in sub-lakes might mitigate the impact of drought on the piscivorous Oriental Storks.

Two questions in the research of animal personality—whether there is a correlation between a personality trait and individual reproductive success, and what is the genetic basis underlying a personality trait—remain unresolved. We addressed these two questions in three shrub-nesting birds, the Azure-winged Magpie (Cyanopica cyanus, AM), White-collared Blackbird (Turdus albocinctus, WB), and Brown-cheeked Laughingthrush (Trochalopteron henrici, BL). The personality type of an individual was first identified according to its response to a territorial intruder. Then, we compared the fleeing distance, breeding parameters, and differential expressed genes (DEGs) in the brain transcriptome between bold and shy breeders. In the three species, bold breeders exhibited more aggressiveness towards an intruder of their territory than did shy breeders. The reproductive success of bold breeders was significantly higher than that of shy breeders in AM but not in WB and BL. The three species shared one DEG, crabp1, which was up-regulated in bold relative to in shy individuals. By regulating the expression of corticotropin-releasing hormone, higher crabp1 gene expression can decrease cellular response to retinoic acid. Therefore, bold individuals are insensitive to external stresses and able to exhibit more aggressiveness to intruders than their shier counterparts. Aggressiveness is beneficial to bold individuals in AM but not in WB and BL because the former could evoke neighbors to make the same response of defending against intruders but the latter could not. Although a personality trait may have the same genetic basis across species, its correlation with reproductive success depends largely on the life history style of a 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.

Embryonic development is a critical period for phenotype formation. Environmental variation during embryonic development can induce changes in postnatal phenotypes of animals. The thyroxine secretion and aerobic metabolic activity of small birds are important phenotypes closely related to their winter survival. In the context of climate change, it is necessary to determine whether temperature variation during incubation in birds leads to developmental plasticity of these cold responsive phenotypes. We incubated Japanese Quail (Coturnix japonica) eggs at 36.8 °C, 37.8 °C, and 38.8 °C, and raised the chicks to 35-day old at 22 °C with same raising conditions, then all the quails were exposed to gradually temperature dropping environment (from 15 °C to 0 °C). After cold treatment, serum T3 level, resting metabolic rate, skeletal muscle and liver metabolomes of the birds were measured. The serum T3 levels were significantly lower in the 38.8 °C group and significantly higher in the 36.8 °C group compared to the 37.8 °C group. The metabolic rate in the 38.8 °C group was significantly lower compared to the 37.8 °C group. Compared with the 37.8 °C group, metabolites involved in the tricarboxylic acid cycle in the liver were significantly lower in the 38.8 °C group, and metabolites related to lipid oxidation metabolism and fatty acid biosynthesis were significantly lower in the skeletal muscles in the 38.8 °C group but significantly higher in the 36.8 °C group. These results indicate that incubation temperature variation can lead to developmental plasticity in cold responsive physiological phenotypes. Higher incubation temperature may impair the capacity of birds coping with cold challenge.

Functionally referential signals are a complex form of communication that conveys information about the external environment. Such signals have been found in a range of mammal and bird species and have helped us understand the complexities of animal communication. Corvids are well known for their extraordinary cognitive abilities, but relatively little attention has been paid to their vocal function. Here, we investigated the functionally referential signals of a cooperatively breeding corvid species, Azure-winged Magpie (Cyanopica cyanus). Through field observations, we suggest that Azure-winged Magpie uses referential alarm calls to distinguish two types of threats: ‘rasp’ calls for terrestrial threats and ‘chatter’ calls for aerial threats. A playback experiment revealed that Azure-winged Magpies responded to the two call types with qualitatively different behaviors. They sought cover by flying into the bushes in response to the ‘chatter’ calls, and flew to or stayed at higher positions in response to ‘rasp’ calls, displaying a shorter response time to ‘chatter’ calls. Significant differences in acoustic structure were found between the two types of calls. Given the extensive cognitive abilities of corvids and the fact that referential signals were once thought to be unique to primates, these findings are important for expanding our understanding of social communication and language evolution.