Avian Research最新文献

Variations in host traits that influence their exposure and susceptibility may impact probability of vector-transmitted diseases. Therefore, identifying the predictors of infection probability is necessary to understand the risk of disease outbreaks during expanding environmental perturbation. Here, we conducted a large survey based on microscopic examination and molecular analysis of haemosporidian parasite infection in raptors rescued at the Beijing Raptor Rescue Centre. Combining these data with biological and ecological variables of the raptors, we determined predictors that affect the probability of haemosporidian infection using generalized linear mixed models and multimodel inference. Our results showed that infection probability exhibited considerable variation across host species in raptors, and body mass, sex, and evolutionary history played relatively weaker roles in driving infection probability. Instead, activity pattern, age, geographic range size, migration distance, and nest type were important predictors of the probability of haemosporidian infection, and the role of each predictor differed in the three main haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon). This macro-ecological analysis will add to our understanding of host traits that influence the probability of avian haemosporidian infection and will help inform risk of emerging diseases.

Extra-pair paternity (EPP) is commonly found in socially monogamous birds, especially in small passerine birds, and there are interspecific and intraspecific variations in the extent of EPP. The Chestnut-vented Nuthatch (Sitta nagaensis) is a socially monogamous passerine bird, and verifying whether this species has EPP relies on parentage testing—S. nagaensis is not known to have EPP. In this study, we developed SNP markers of this species that are informative for parentage analysis from double digest restriction site-associated DNA sequencing (ddRAD-seq) data. A panel consisting of 50 SNP markers, with a mean heterozygosity of 0.343, was used to resolve 95% of nestlings to fathers. The combined exclusion probabilities for the first parent and second parent were 0.991 and 0.9999, respectively. This panel of SNP markers is a powerful tool for parentage assignments in S. nagaensis. In addition, we found that three offspring (7.9%) from three nests (23.1%) were the result of extra-pair fertilization out of 38 offspring in 13 nests. Our study provided information on parentage analysis that has not been reported before in S. nagaensis. It also supplemented the understudied EPP behavior of birds in Asia, contributing to a general understanding of the EPP behaviors of birds.

The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution. Avian brood parasitism reduces the reproductive success of hosts, and thus, hosts have evolved anti-parasitic strategies, such as rejecting parasitic eggs and adopting aggressive nest defense strategies, to avoid the cost brought on by brood parasitism. To test whether host anti-parasitic strategies are adjusted with the risk of being parasitized when the breeding seasons of brood parasites and hosts are not synchronous, we conducted a field experiment assessing nest defense and egg recognition behaviors of the Isabelline Shrike (Lanius isabellinus), a host of the Common Cuckoo (Cuculus canorus). In the local area, the host Isabelline Shrike begins to breed in April, whereas the summer migratory Common Cuckoo migrates to the local area in May and begins to lay parasitic eggs. Results showed that nest defense behaviors of the Isabelline Shrike increases significantly after cuckoo arrival, showing higher aggressiveness to cuckoo dummies, with no significant difference in attack rates among cuckoo, sparrowhawk and dove dummies, but their egg rejection did not change significantly. These results imply that Isabelline Shrikes may adjust their nest defense behavior, but not egg rejection behavior, with seasonality.

Individuals may gather information about environmental conditions when deciding where to breed in order to maximize their lifetime fitness. They can obtain social information by observing conspecifics and heterospecifics with similar ecological needs. Many studies have shown that birds can rely on social information to select their nest sites. The location of active nests and the reproductive success of conspecifics and heterospecifics can provide accurate predictions about the quality of the breeding habitat. Some short-lived species can facultatively reproduce two and/or more times within a breeding season. However, few studies have focused on how multiple-brooding individuals select nest sites for their second breeding attempts. In this study, we use long-term data to test whether the Japanese Tit (Parus minor) can use social information from conspecifics and/or heterospecifics (the Eurasian Nuthatch Sitta europaea, the Daurian Redstart Phoenicurus auroreus and the Yellow-rumped Flycatcher Ficedula zanthopygia) to select a nest site for the second breeding attempt. Our results showed that the nest boxes occupied by tits on their second breeding attempt tended to be surrounded by more breeding conspecific nests, successful first nests of conspecifics, and fewer failed first nests of conspecifics than the nest boxes that remained unoccupied (the control group). However, the numbers of breeding heterospecific nests, successful heterospecific nests, and failed heterospecific nests did not differ between the nest boxes occupied by tits on their second breeding attempt and the unoccupied nest boxes. Furthermore, the tits with local successful breeding experience tended to choose areas with more successful first nests of conspecifics than those without successful breeding experience. Thus, we suggest that conspecifics' but not heterospecifics’ social information within the same breeding season is the major factor influencing the nest site selection of Japanese Tits during second breeding attempts.

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.