Avian Research最新文献

Common Cuckoos (Cuculus canorus) dependent on parental care for post-hatching demonstrate an intriguing ability to modify their begging vocalizations to ensure maximum care and resources from their interspecific foster parents. Here, we compared begging calls of the Common Cuckoo nestlings fed by four host species, the Grey Bushchat (Saxicola ferreus), Siberian Stonechat (Saxicola maurus), Daurian Redstart (Phoenicurus auroreus), and Oriental Magpie-robin (Copsychus saularis). Results showed that begging calls of the stonechat–, redstart–, and robin–cuckoo resemble those of host species' nestlings in various aspects like low frequency, high frequency, frequency bandwidth and peak frequency, while the bushchat–cuckoo chicks' begging calls were only comparable to their host species in terms of how long they lasted and their peak frequency. In addition, cuckoo nestlings raised in different host nests displayed significant variations in their begging calls in low and peak frequency. This study suggests that cuckoo nestlings do not mimic host species nestlings' begging calls throughout the nestling period, but may tune their begging calls according to host species, while begging calls vary with cuckoo and host species nestlings' ages. Future research should study the parents’ reactions to these calls in different host species for a better understanding of the mechanisms underlying such adaptations.

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.

The gut microbiota of migratory waterbirds is affected by various complex factors, including cross-species transmission, which increases the risk of pathogen spreading among sympatric animals and poses a potential public health risk to humans. In this study, we investigated the microbial communities of wintering Bean Geese (Anser fabalis), Domestic Ducks (A. platyrhynchos domesticus), humans, and soil using high-throughput sequencing of the 16S rRNA gene region in Shengjin Lake, China. In total, 6,046,677 clean reads were obtained, representing 41,119 operational taxonomic units (OTUs) across the four groups. The dominant microbial phyla were the Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota. The Sorensen similarity index and alpha and beta diversity results showed that the gut microbial communities of Bean Geese and Domestic Ducks were more similar to those of the other pairs. Network analysis revealed that Faecalibacterium prausnitzii, Pseudomonas fragi, and Bradyrhizobium elkanii were hubs of the three major modules. Fourteen common microbiomes were identified in Bean Geese, Domestic Ducks, humans, and soil in Shengjin Lake. A total of 96 potential pathogens were identified among the four groups, with 20 specific potentially pathogenic microbiomes found in the gut of Bean Geese. Some of these pathogens are responsible for significant financial losses in the poultry industry and pose risks to human health. Klebsiella pneumoniae, Morganella morganii, Escherichia coli, and Ralstonia insidiosa are potential core pathogens found in the four groups at Shengjin Lake that can cause diseases in humans and animals and facilitate cross-species transmission through various media. Therefore, humans are at risk of contracting these pathogens from migratory birds because of their frequent contact with domestic poultry. However, further studies are required to explore the potential pathogenic species and transmission pathways among sympatric wintering Bean Geese, Domestic Ducks, humans, and soil.

Cold spells and severe weather may have detrimental effects in wild birds, but owing to the stochastic nature of these events, it is not always possible to measure their impacts. In January 2021, a strong snowstorm known as ‘Filomena’ affected Spain, mainly the region of Madrid (Central Spain), which was fully covered with snow and suffered freezing temperatures for a fortnight. Using bird surveys conducted in the winter-spring of 2020 and 2021 (before and after Filomena) at same locations, we addressed the possible impact of the cold spell in three widespread gamebirds: Wood Pigeon (Columba palumbus), Eurasian Magpie (Pica pica) and Red-legged Partridge (Alectoris rufa). No significant abundance differences were found between years for none of the species and hunting pressure was only significantly reduced for Partridges, hence this species may have been negatively affected by Filomena. Results suggest that in response to Filomena, Pigeons conducted partial migration in search of better conditions, while Magpies aggregated in certain areas of Madrid and Partridges endured the harsh conditions within their home ranges. Our results highlight the importance to alleviate negative impacts of extreme weather events in wild birds through management actions, especially for sedentary species.

Birds, a fascinating and diverse group occupying various habitats worldwide, exhibit a wide range of life-history traits, reproductive methods, and migratory behaviors, all of which influence their immune systems. The association between major histocompatibility complex (MHC) genes and certain ecological factors in response to pathogen selection has been extensively studied; however, the role of the co-working molecule T cell receptor (TCR) remains poorly understood. This study aimed to analyze the copy numbers of TCR-V genes, the selection pressure (ω value) on MHC genes using available genomic data, and their potential ecological correlates across 93 species from 13 orders. The study was conducted using the publicly available genome data of birds. Our findings suggested that phylogeny influences the variability in TCR-V gene copy numbers and MHC selection pressure. The phylogenetic generalized least squares regression model revealed that TCR-Vαδ copy number and MHC-I selection pressure were positively associated with body mass. Clutch size was correlated with MHC selection pressure, and Migration was correlated with TCR-Vβ copy number. Further analyses revealed that the TCR-Vβ copy number was positively correlated with MHC-IIB selection pressure, while the TCR-Vγ copy number was negatively correlated with MHC-I peptide-binding region selection pressure. Our findings suggest that TCR-V diversity is significant in adaptive evolution and is related to species’ life-history strategies and immunological defenses and provide valuable insights into the mechanisms underlying TCR-V gene duplication and MHC selection in avian species.

Nestling growth of birds can be affected by weather fluctuations. In general, it is expected that higher temperatures favor growth by improving food availability and nestling metabolism, while rain hinders it by reducing foraging efficiency. However, most of these patterns have been described in insectivorous cavity-nesting birds in temperate forests. We tested these predictions in two neotropical grassland ground-nesting birds with contrasting nestling diets and therefore potentially different responses to weather. We measured nestlings of the Hellmayr's Pipit (Anthus hellmayri, an insectivorous passerine) and the Grassland Yellow-Finch (Sicalis luteola, which feeds its nestlings exclusively with seeds) during three breeding seasons (2017–2020) in central-eastern Argentina. We took measurements of tarsus and body mass, modeled growth curves using nonlinear mixed-effects models, and evaluated the effects of minimum daily temperature and precipitation during the growth period and the 30 days prior to hatching. For pipits (60 nestlings from 21 nests), minimum temperatures during the growth period were positively associated with tarsus and body mass asymptotes. Also, there was a positive association between precipitation during the pre-hatching period and tarsus asymptote. Conversely, none of the weather variables analyzed had significant effects on nestling growth of finches (131 nestlings from 35 nests). Dietary contrast between species may explain the different results. Arthropod activity and abundance can be affected by weather variations within the span of a breeding season, whereas seeds may depend on conditions from previous years, making the effects harder to detect. Fledglings with reduced asymptotic size can have reduced chances of survival. Hence, pipit populations could be impacted if they experience cold and dry conditions during their breeding season, which is of major relevance in the current context of climate change.

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.

Genetic load and inbreeding are recognized as important factors to be considered in conservation programs. Elevated levels of both can increase the risk of population extinction by negatively impacting fitness-related characters in many species of plants and animals, including humans (inbreeding depression). Genomic techniques are increasingly used in measuring and understanding genetic load and inbreeding and their importance in evolution and conservation. We used whole genome resequencing data from two sibling grouse species in subarctic Eurasia to quantify both. We found a large range of inbreeding measured as F_ROH (fraction of runs of homozygosity) in individuals from different populations of Chinese Grouse (Tetrastes sewerzowi) and Hazel Grouse (T. bonasia). F_ROH estimated from genome-wide runs of homozygosity (ROH) ranged from 0.02 to 0.24 among Chinese Grouse populations and from 0.01 to 0.44 in Hazel Grouse. Individuals from a population of Chinese Grouse residing in the Qilian mountains and from the European populations of Hazel Grouse (including samples from Sweden, Germany and Northeast Poland) were the most inbred (F_ROH ranged from 0.10 to 0.23 and 0.11 to 0.44, respectively). These levels are comparable to other highly inbred populations of birds. Hazel Grouse from northern China and Chinese Grouse residing in the Qinghai-Tibetan Plateau showed relatively lower inbreeding levels. Comparisons of the ratio between deleterious missense mutations and synonymous mutations revealed higher levels in Chinese Grouse as compared to Hazel Grouse. These results are possibly explained by higher fixation rates, mutational melt down, in the range-restricted Chinese Grouse compared to the wide-ranging Hazel Grouse. However, when we compared the relatively more severe class of loss-of-function mutations, Hazel Grouse had slightly higher levels than Chinese Grouse, a result which may indicate that purifying selection (purging) has been more efficient in Chinese Grouse on this class of mutations.