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The post-fledging period, defined as the period after a young bird leaves its nest, is a crucial stage for birds and is often when they face the highest risk of mortality. Current management for breeding birds has been primarily informed by the nesting and adult stages while the post-fledging period is often understudied, despite birds spending an equal or greater amount of time in the post-fledging period than they do in the nest. In 2020 and 2021 we documented habitat used, including water depth and vegetation height, cover, and type, and survival of 50 fledglings of Least Bittern (Ixobrychus exilis), a cryptic marsh bird of conservation concern in the midwestern United States. We compared habitat used by fledglings to habitat at randomly selected points within a daily dispersal distance determined by the fledgling's age. Fledglings used points with denser and taller marsh vegetation than random points and they relied on persistent emergent vegetation, which likely provides greater predator protection, thermal refuge, and foraging opportunities. Fledgling habitat use was age-dependent and related to flight ability, with younger, pre-flight fledglings using denser habitats and older juveniles with flight ability using more open habitat. Additionally, 86% of Least Bittern fledglings survived until 30 d post-hatch (when they often left the marsh they hatched in), a higher survival rate than in the limited previous studies of fledglings. Mortality resulted from predation and exposure, and the greatest mortality risk was in the 3 d following fledging and in 2020. Our results suggest that managing for a diversity of marsh habitats, including both densely vegetated habitats commonly used by nesting Least Bitterns and more open marsh habitats, is important for fledglings. [ABSTRACT FROM AUTHOR]

The article discusses the One Hundred Fifth Annual Meeting of the Wilson Ornithological Society (WOS), held jointly with the Association of Field Ornithologists (AFO) and Society of Canadian Ornithologists-Société des Ornithologistes du Canada (SCO-SOC) in Peoria, Illinois, from 29 July to 2 August 2024.

Animal sociality ranges from predominantly solitary life to complex multilevel societies in which stable core units merge into increasingly inclusive entities. To understand the evolutionary pathways and mechanisms that promote and maintain animal sociality in different taxa, it is crucial to uncover whether conspecific aggregations result from true social attraction or nonsocial forcing factors (e.g. localized resource) and whether social preference is maintained in different contexts. Here, we show that, in cooperatively breeding carrion crows, Corvus corone , core social units persist at higher levels of aggregations (roosts). In our study population, individuals live in cohesive territorial kin groups year-round in an all-purpose territory. At night, crows from different territories may sleep communally in one of the four roosts available in the area. By radiotracking 73 individuals, we found that roosts were used mainly in winter and on cold nights in autumn and spring, suggesting a thermoregulatory function of nocturnal aggregations. Interestingly, we also discovered that members of the same social group preferentially used the same roost, showing a social cohesion that was not achieved by mere attraction to the same roosting site but was based on an active choice of joining groupmates. Therefore, our results indicate that social preference persists in different aggregation contexts in cooperative crows, revealing a further complexity of their society and suggesting a social function of roosts. However, different social groups did not merge in a stable and predictable way at the roost level, providing weak support for a multilevel society in this population. • Cooperatively breeding carrion crows live in territorial kin groups. • When they congregate in large communal roosts, groupmates stay together. • Group cohesiveness in different contexts is maintained by true social preference. • Communal roosts may play a major role in crow social networking. [ABSTRACT FROM AUTHOR]

Recordings from external and internal cameras in nest boxes provided insights into the breeding activities of two pairs of Common Swifts in the breeding season 2020 in Laufen (canton of Basel-Landschaft) in north-western Switzerland. It was possible to distinguish between the five adult birds present based on small features in their plumage or the presence of a ring, which allowed a detailed analysis of the birds' presence in the nest boxes and of their feeding behaviour. Both pairs successfully raised three young. On cool and rainy days, the adults stayed in the nest box longer in the morning or did not fly out at all, or only briefly. A total of eight approaches by a Common Kestrel triggered strong reactions from the breeding birds present: They stayed in the nest box significantly longer afterwards, before setting off on their next foraging flight, than when they flew in before or after the approach by a Kestrel. During the incubation period, both adults of a pair were present for similar lengths of time, and the feeding rate was also similar for males and females. Entries by other Common Swifts into unoccupied boxes were usually brief. In one of the two nest boxes equipped with a camera, a new male returned a few days earlier than the previous year's breeding pair and then displaced the previous year's male in a five-hour battle when the pair arrived. Together with the previous year's female, he then formed a pair and they began to breed together. However, in the middle of the breeding season, the previous year's male managed to take over the nest box and chase away the new male (the presumed father of the young). The young birds were between 10 and 12 days old at this time. For the next 10 days, the previous year's male initially did not participate in feeding the young. The female compensated for this by significantly increasing the number of feedings for several days. This suggests that it is possible for a single adult Common Swift to provide three young with sufficient food when the breeding partner is absent, at least in good weather conditions. [ABSTRACT FROM AUTHOR]

Aim: Seasonality governs species composition at a given place and time. However, the effects of climate and land‐use change can vary by season, altering species composition. These changes can lead to a loss of distinct seasonal community composition, representing a novel form of biotic homogenisation. We ask if breeding and winter bird communities are becoming more similar over time. If so, is homogenisation occurring more rapidly in winter than in the breeding season, and has the presence of individual species changed between seasons? Location: Northeastern United States. Time Period: 1989–2019. Major Taxa Studied: Two hundred thirty‐eight bird species. Methods: We use data from The National Audubon Society's Christmas Bird Count and the North American Breeding Bird Survey to test if winter and breeding bird communities have become more similar (homogenised). We evaluate this change using the Sørensen dissimilarity index, and its components of turnover (species replacement) and nestedness (a subset of a more species rich community) and describe the mechanism in which the seasonal winter and breeding bird communities are changing. Results: We found that winter and breeding bird communities are homogenising, driven by significant decrease in turnover and a marginal decrease nestedness. When viewing breeding and wintering communities separately, we observe different trends. Breeding communities are becoming more unique with decreasing turnover and nestedness. Winter communities are becoming more similar to each other, with decreasing turnover and nestedness. More breeding species are declining and species that are typically found in the winter and year‐round residents are the main contributors to the homogenisation between seasons. Main Conclusions: We show for the first time homogenisation between winter and breeding bird communities over time across the northeastern United States. This insight into how individual species are faring between seasons, and how they impact community structure, can be used when implementing conservation measures for maintaining ecological functioning and integrity. [ABSTRACT FROM AUTHOR]

Hypersensitivity pneumonitis (HP) caused by avian antigens is one of the most prevalent forms of HP, with pigeon antigens being the most common culprits. While the health effects on pigeon breeders are well documented, there is limited information on the impact that pigeon breeding has on the health of family members and individuals living near breeding pigeons. This case study describes the condition of a 56-year-old housewife who was referred to an academic hospital's respiratory outpatient department with a principal complaint of six years of progressively worsening dyspnoea and intermittent dry cough. Comprehensive evaluations included a physical examination, chest X-rays (CXR), highresolution computed tomography (HRCT) and lung-function testing. Her blood was analysed for specific immunoglobulin G (sIgG) to avian antigens due to the patient's husband breeding birds at their residence for racing. The clinical work-up suggested an HP diagnosis supported by the laboratory analysis of elevated sIgG antibodies to pigeon mix Ge 91 (pigeon serum proteins, feathers and droppings) and Ge 93 (pigeon serum proteins). These results enabled a confirmatory diagnosis of HP to secondary pigeon exposure. The findings underscore the importance of incorporating sIgG testing to support an HP diagnosis, which is critical to effective disease and exposure management. This case emphasises the necessity of establishing national reference ranges for IgG against common antigens to improve the utility of sIgG antigen testing in the HP diagnostic framework. In addition, it highlights the importance of monitoring exposures in rapidly growing cottage industries in South Africa to reduce the risk of exposure to people, animals and the environment. [ABSTRACT FROM AUTHOR]

The article discusses cannibalism observed in northern giant petrels at Possession Island in the Southern Indian Ocean. The study highlights instances of cannibalism among the petrels, which is attributed to opportunistic feeding behavior and specific environmental conditions. The research also explores the impact of cannibalism on breeding failures and the need for further investigation into the drivers of this behavior. The study emphasizes the need for more research to understand the role of cannibalism in the feeding repertoire of giant petrels and its implications for breeding success. [Extracted from the article]

In Mediterranean wetlands, Phragmites australis reed beds are often intensively managed through mowing. These practices may improve wetland heterogeneity with contrasting effects on many reed-bed related birds. Here, we analyzed the habitat selection of a guild of six water-related breeding birds in a patchy managed wetland, where reed-bed mowing was periodically carried out. We reported data about the habitat use and selection of species on five different habitat patches (non-managed mature and managed by mowing reed-beds, rush-beds, open waters, and ecotones), both considering species abundance and biomass. Moreover, we focused on differences between non-managed/mature reed-beds and managed (mowed) ones. As expected, all the species showed a significant difference in frequency of habitat use, both considering abundance and biomass. As expected, rails (Eurasian coot, Moorhen), Mallard and Little grebe selected open waters, Reed warbler selected reed beds and Cetti’s warbler selected ecotones. Detrended Correspondence Analysis (DCA) performed on abundance values confirmed the link among habitats and species. However, when performing DCA on biomasses, we showed a shift of the largest species toward mowed reed-beds. The direct comparisons between mature and managed (mowed) reed-beds, using the Abundance/Biomass comparisons, highlighted the difference in abundance and biomass when comparing these habitat patches: in mature reed-beds the biomass curve was located below the abundance one (high frequency in abundance of low biomass birds, as warblers), whilst in mowed reed-beds the biomass curve was located above the abundance one (comparable high frequency of large biomass species, such as ducks, rails and grebe). Although our data suggest reed-bed mowing may disadvantage small passerines, we observed this type of management may favor large body species, providing them a higher availability of shelters and breeding sites. [ABSTRACT FROM AUTHOR]

Spirulina is increasingly being used in feed manufacturing because of its high nutritional value, especially proteins, for humans and animals. This study examined the feed intake and growth performance of Boschveld and Potchefstroom Koekoek chicken breeds when soybean meal was substituted with incremental levels of Spirulina platensis. The experimental design was a 2 × 4 factorial with repeated measures over a 12-week period, with breed and diet as factors. The experimental unit was a cage holding 3 birds, with 3 cages allocated to each breed-diet combination, hence 36 birds per breed. The diets were: 0%, 5%, 10% and 15% using dried Spirulina platensis powder to replace soybean meal per 100 kg of feed. Chickens fed control diet consumed more (P < 0.05) feed than those fed Spirulina-containing diets. Diet affected (P < 0.0001) final weights (g) of the birds which were 1093.2, 921.6, 762.8 and 771.2 for 0%, 5%, 10% and 15% inclusion levels of Spirulina platensis, respectively. Boschveld chickens had better average daily gain compared to Potchefstroom Koekoek at week 15–16. Averaged over the 12 weeks, the control diet gave better (P < 0.0001) average daily gain (9.42 g/d) than the Spirulina-containing diets. Over the 12 weeks, the control diet had a more desirable (7.79 vs. 8.17, P = 0.01) feed conversion ratio than the Spirulina-containing diets Spirulina at a level of 5–10% can be used as a protein supplement in indigenous chicken feeds because it resulted in growth performance close to control diets. [ABSTRACT FROM AUTHOR]

Primate brain development is shaped by inputs received during critical periods. These inputs differ between independent and cooperative breeders: In cooperative breeders, infants interact with multiple caregivers. We study how the neurodevelopmental timing of the cooperatively breeding common marmoset maps onto behavioral milestones. To obtain structure-function co-constructions, we combine behavioral, neuroimaging (anatomical and functional), and neural tracing experiments. We find that brain areas critically involved in observing conspecifics interacting (i) develop in clusters, (ii) have prolonged developmental trajectories, (iii) differentiate during the period of negotiations between immatures and multiple caregivers, and (iv) do not share stronger connectivity than with other regions. Overall, developmental timing of social brain areas correlates with social and behavioral milestones in marmosets and, as in humans, extends into adulthood. This rich social input is likely critical for the emergence of their strong socio-cognitive skills. Because humans are cooperative breeders too, these findings have strong implications for the evolution of human social cognition. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms behind biodiversity dynamics is central to assessing and forecasting anthropogenic impacts on ecological communities. However, the manner in which external environmental drivers act in concert with intrinsic ecological processes to influence local temporal turnover is currently largely unexplored. Here, we determine how human impacts affect multiple metrics of bird community turnover to establish the ecological mechanisms behind compositional change. We used US Breeding Bird Survey data to calculate transect‐level rates of three measures of temporal species turnover: (1) "short‐term" (initial rate of decline of Sørensen similarity), (2) "long‐term" (asymptotic Sørensen similarity), and (3) "throughput" (overall species accumulation rate from species–time relationship exponents) over 2692 transects across 27 regional habitat types. We then hierarchically fit linear models to estimate the effect of anthropogenic impact on these turnover metrics, using the Human Modification Index proxy, while accounting for observed species richness, the size of the species pool, and annual environmental variability. We found broadly consistent impacts of increased anthropogenic pressures across diverse habitat types. The Human Modification Index was associated with greater turnover at long timescales, but marginally slower short‐term turnover. The species "throughput" (accumulation rate) was not notably influenced. Examining anthropogenic impacts on different aspects of species turnover in combination allows greater ecological insight. Observed human impacts on short‐term turnover were the opposite of existing expectations and suggest humans are disrupting the background turnover of these systems, rather than simply driving rapid directed turnover. The increased long‐term turnover without concurrent increases in species accumulation implies human impacts lead to shifts in species occurrence frequency rather than simply greater arrival of "new" species. These results highlight the role of intrinsic dynamics and caution against simple interpretations of increased species turnover as reflections of environmental change. [ABSTRACT FROM AUTHOR]

Aim: Ongoing climate changes represent a major determinant of demographic processes in many organisms worldwide. Birds, and especially long‐distance migrants, are particularly sensitive to such changes. To better understand these impacts on long‐distance migrants' breeding productivity, we tested three hypotheses focused on (i) the shape of the relationships with different climate variables, including previously rarely tested quadratic responses, and on regional differences in these relationships predicted by (ii) mean climatic conditions and (iii) by the rate of climate change in respective regions ranging from Spain to Finland. Location: Europe. Time Period: 2004–2021. Major Taxa Studied: Long‐distance migratory passerine birds. Methods: We calculated breeding productivity from constant effort ringing sites from 11 European countries covering 34° of latitude, and extracted temperature‐ and precipitation‐related climate variables from E‐OBS and NASA MODIS datasets. To test our hypotheses, we fitted GLMM and Bayesian meta‐analytic models. Results: We revealed hump‐shaped responses of productivity to temperature, growing degree‐days, green‐up onset date, and precipitation anomaly, and negative responses to intense and prolonged rains across the regions. The effects of March temperature and April growing degree‐days were more negative in cold than in warm regions, except for the region with the highest accumulated heat, whereas increasing June precipitation anomalies were associated with higher productivity in both dry and wet regions. Productivity responses to climate were unrelated to the rate of climate warming. Main Conclusions: The influence of climate on bird productivity proved to be frequently nonlinear, as expected by ecological theory. The rate of climate change is less important than regional interannual variability in climate (which is predicted to increase), but this may change with the progression of climate change in the future. Productivity declines in long‐distance migratory songbirds are particularly expected if out‐of‐norm water excess increases in frequency or strength. [ABSTRACT FROM AUTHOR]

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The alterations of phenotypic traits (morphology, endocrine physiology, and behavior) in response to predictable environmental cues across life‐history stages in seasonally breeding birds enable successful culmination of reproduction. The present study elucidated the plasticity of the hypothalamic–pituitary–adrenal (HPA) axis in a subtropical free‐living finch, Amandava amandava amandava, and suggests the crucial role of the baseline corticosterone (CORT) to coordinate energetic readiness across life‐history stages. Birds were captured monthly from an area (25.1337° N 82.5644° E) in Uttar Pradesh, India, from June 2014 to May 2015. Only male birds were included in this study corresponding to different life‐history stages (6/life‐history stage; 2/month): pre‐breeding (June–August), breeding (September–November), post‐breeding (December–February), and quiescent phases (March–May). The pituitary expression of adrenocorticotropic hormone (ACTH), adrenal interrenal cell morphometry, and plasma level of the CORT showed varied patterns across life‐history stages. The density and immunointensity of the ACTH‐immunoreactive corticotropes and the interrenal cell number increased along with the significant plasma CORT elevation during the breeding cycle (both pre‐breeding and breeding phases). CORT might facilitate the energy demand for the display of sexual behavior (nest‐building, courtship), testicular recrudescence, and foraging of food for offspring during the breeding cycle. On the contrary, plasma CORT decrease in the post‐breeding and quiescent phases might enable the bird to molt avoiding the protein catabolic effect of the hormone. Given the complexity involved in the study of baseline CORT in free‐living birds, more studies are needed to better understand the crucial role of the HPA axis in the modulation of life‐history stages in this and other subtropical avian species. [ABSTRACT FROM AUTHOR]

The Indian spot-billed duck, Anas poecilorhyncha is a large dabbling and non-migratory breeding bird. The identification and phylogenetic relationship of A. poecilorhyncha remain uncertain due to the presence of overlapping meristic characters and hybridization with closely related species. Molecular data aids when there are challenges in morphological identification. However, genetic characterization of A. poecilorhyncha has been paid less attention. Apart from their functional and physiological role, mitochondrial genome can also be used for various purposes, including species identification, phylogenetic analysis, understanding the domestication history of species etc. Therefore, the present study aimed to sequence the mitochondrial genome of A. poecilorhyncha and its closely related domestic species A. platyrhynchos (mallard duck) to understand their mitochondrial genome structure and phylogenetic relationships. The length of mitochondrial genome of A. poecilorhyncha and A. platyrhynchos was 16,608 and 16,604 bp respectively. Mitochondrial genome contained 37 genes and a non-coding control region. Overall, the characteristics of mitochondrial genome of both species were found to be conserved. The phylogenetic tree exhibited seven major clades (A to G) with a high bootstrap support. Notably, the Indian A. poecilorhyncha population formed a distinct clade (C) whereas the A. poecilorhyncha that were probably sampled from China grouped along with A. zonorhyncha (clade B). Besides, one of the A. poecilorhyncha probably sampled from China was placed in the clade A, which predominantly consisted of A. platyrhynchos. It suggests that Indian A. poecilorhyncha population is genetically different from Chinese A. poecilorhyncha population. Further, it sheds light on the importance of conducting a comprehensive phylogenetic study on these species. The newly sequenced mitochondrial genome of A. poecilorhyncha and A. platyrhynchos would be useful not only to have a better understanding of the phylogeny and evolution of Anas species but also to help in the conservation of A. poecilorhyncha which is under constant threat from rapid urbanization, interspecific hybridization and other human activities. [ABSTRACT FROM AUTHOR]

Climate change is shifting the phenology of migratory animals earlier; yet an understanding of how climate change leads to variable shifts across populations, species and communities remains hampered by limited spatial and taxonomic sampling. In this study, we used a hierarchical Bayesian model to analyse 88,965 site‐specific arrival dates from 222 bird species over 21 years to investigate the role of temperature, snowpack, precipitation, the El‐Niño/Southern Oscillation and the North Atlantic Oscillation on the spring arrival timing of Nearctic birds. Interannual variation in bird arrival on breeding grounds was most strongly explained by temperature and snowpack, and less strongly by precipitation and climate oscillations. Sensitivity of arrival timing to climatic variation exhibited spatial nonstationarity, being highly variable within and across species. A high degree of heterogeneity in phenological sensitivity suggests diverging responses to ongoing climatic changes at the population, species and community scale, with potentially negative demographic and ecological consequences. [ABSTRACT FROM AUTHOR]

Breeding behaviour is a key process for avian fitness and evolution, but the basic natural histories of many species are unknown. We studied the breeding biology of D'Arnaud's Barbet Trachyphonus darnaudii (family Lybiidae) on the Usangu Plains in southwestern Tanzania. The birds excavated a vertical tunnel into the soil, expanding into a nesting chamber about 46 cm below the surface. Nests were located in small territories (between 500 and 10 000 m²) defined by song perches visited for duetting (and sometimes for chorusing). Probing the nesting chambers with a wireless endoscope camera enabled the first images of the eggs and the young of this species in the wild. On average, the clutch size was 3.8 eggs, birds incubated for 15.3 days, the nestling period was 28 days, and 2.5 young fledged from a nest. The nestlings were mainly fed insects, which may explain why the birds breed during the wet season (when insects are abundant) despite the potential risk of the subterranean nests being flooded. [ABSTRACT FROM AUTHOR]

The association between migratory strategies and life-history traits helps explain how migratory organisms balance the energetic costs and survival risks with the benefits of migration. However, there is no consensus on how life-history traits associate with migration, and on migrant's position at the slow–fast continuum of life history. Birds subject to different selective pressures are likely to show distinct patterns from each other. We used data from egg collections to investigate the relationship between reproduction and migration by assessing clutch size and egg size of 58 migratory and non-migratory tyrant flycatchers breeding in South America. We first compared clutch size and egg size of migrants and non-migrants, and then we assessed how migrants balance these reproductive traits with migration distance. Despite energy expenditure faced by migrants during their journey, migratory behavior was not a factor influencing clutch size and egg size of migrants and non-migrants. On the other hand, migration distance positively correlated with clutch size in migrants. Our study provides evidence that migration distance may constrain migrants in terms of costs and pressure reproduction in the direction of a faster life-history strategy, while migratory behavior per se may not be a determinant to place migrants in the slow–fast continuum of life history. Thus, among tyrant flycatchers breeding in South America variation in migratory strategies might be more important than migratory behavior in interacting with life-history traits. This study also demonstrates the potential of museum egg collections to test ecological hypotheses that investigate large-scale variation in breeding parameters of birds. [ABSTRACT FROM AUTHOR]

Breeding success of birds depends on survival during two critical stages of the reproductive period: First, egg laying and incubation, and then nestling and fledgling. This essential element of avian life history mirrors an evolutionary adaptation of parents to existing environmental conditions. The main factors that determine nest survival involve weather, predation and sibling competition. Despite numerous studies documenting their impact on breeding success, only a few have analysed the issue with regard to ground-nesting birds and estimated their survival functions. Therefore, we decided to examine nest survival probability of the Crested Lark (Galerida cristata) in a population that occupies newly established roadside habitats in Central Poland. The analysis is based on 141 nests monitored between 2018 and 2022. We found that the mean survival probability of the whole nesting period was 0.376, and it was higher during the egg stage (0.836) than during the nestling period (0.392). The Cox proportional hazards model shows that nest survival in the nestling stage is mainly affected by the time of breeding and the distance from the road edge, and also by mean temperature of the whole nesting period. In other words, the probability of a brood failure in the nestling stage decreases as the breeding season advances, whereas it increases among nests located closer to the road edge. Furthermore, during the whole nesting period, nest failure decreases as the temperature rises. Our study suggests that the Crested Lark, being a multi-brood and thermophilic species inhabiting temperate regions, may benefit more if its nesting attempts begin later during the season when breeding conditions become more favourable. However, we also take into consideration a hypothesis that nesting in grassy habitats near road edges may prove to be an ecological trap, attracting high densities of nesting birds but leading to their low nest success. [ABSTRACT FROM AUTHOR]

The Gran Canaria Blue Chaffinch is the rarest forest passerine in the western Palaearctic with a population reduced to a single locality, Inagua, in the west of the island. After a forest fire, some birds were established in another location and a reinforcement programme was launched with the aim of consolidating this new population. Between 2010 and 2019, 194 Blue Chaffinches were released in the pine forest of La Cumbre, in the centre of the island and at a higher altitude than the previous one. Birds of two origins were used for this action: captive-bred birds were released using "soft" release methods, and wild-caught birds from the Inagua source population were released using "hard" release methods. Survival of radio-tagged birds (20–42 days of battery life) was high and similar between the two groups. Wild-caught birds occupied 12–15 times more surface area than captive-bred birds that remained close to supplementary feeding sites. All translocated birds displayed breeding behaviour in the following breeding season, although the rate of contribution to the new population was significantly lower for wild-caught birds (21% compared to 54% for captive-bred birds). This disparity can be partly attributed to nearly one-fifth of the wild-caught birds returning to Inagua. We conclude that the establishment phase of the Blue Chaffinch reinforced program in Gran Canaria has been successful. To retain wild-caught birds and deter their return to the source population, we recommend employing methods akin to the soft-release techniques utilized for captive-bred birds. Ongoing monitoring of the enhanced population, collecting data on survival and breeding success, will enable the evaluation of the long-term success of the translocation program. [ABSTRACT FROM AUTHOR]

Migratory waterfowl are a harvested resource shared among multiple European countries, exposing them to potential overexploitation. Management of take is challenging since the life cycle of migratory waterfowl consists of several stages distributed among several locations, with possible spatio-temporal overlap among populations with differing population trends. Successful harvest management in such situations requires knowledge about the connections between breeding and non-breeding locations, and where birds are harvested. Breeding populations of Eurasian wigeon (Mareca penelope) are declining in Finland, underlining the need for more effective harvest management. Relative proportions and temporal distribution of local breeding birds and migrants from a larger Russian breeding population within the Finnish hunting bag has been unknown to date. We studied spatio-temporal origins of Finnish harvested wigeon by measuring stable-hydrogen (δ2H) isotope values from legally harvested birds. We modelled the changes in δ2H values of the feather samples within the hunting season using Gaussian processes and found that the origin of harvested wigeon in Finland changed during the hunting season and differed by age and sex. In juveniles and adult females but not in adult males, origin of harvested birds shifted from local and possibly western Russian birds to more long-distance migratory birds during the harvest season. These patterns likely reflected sex- and age-specific differences in migratory behaviour of Eurasian wigeon in the East Atlantic flyway, which can be used to guide future management and conservation of this species through the implementation of spatio-temporal harvest regulation. [ABSTRACT FROM AUTHOR]

Hamilton's rule provides the cornerstone for our understanding of the evolution of all forms of social behavior, from altruism to spite, across all organisms, from viruses to humans. In contrast to the standard prediction from Hamilton's rule, recent studies have suggested that altruistic helping can be favored even if it does not benefit relatives, as long as it decreases the environmentally induced variance of their reproductive success ("altruistic bet-hedging"). However, previous predictions both rely on an approximation and focus on variance-reducing helping behaviors. We derived a version of Hamilton's rule that fully captures environmental variability. This shows that decreasing (or increasing) the variance in the absolute reproductive success of relatives does not have a consistent effect--it can either favor or disfavor the evolution of helping. We then empirically quantified the effect of helping on the variance in reproductive success across 15 species of cooperatively breeding birds. We found that a) helping did not consistently decrease the variance of reproductive success and often increased it, and b) the mean benefits of helping across environments consistently outweighed other variability components of reproductive success. Altogether, our theoretical and empirical results suggest that the effects of helping on the variability components of reproductive success have not played a consistent or strong role in favoring helping. [ABSTRACT FROM AUTHOR]

According to sexual selection theory, the sexes are faced with opposing evolutionary goals. Male fitness benefits from access to females, whereas female fitness is constrained by food resources and safety for themselves and their offspring. Particularly in large solitary carnivores, such as polar bears (Ursus maritimus), these divergent goals can potentially lead to conflict between the sexes. Outside the mating season, when polar bears are on the move across vast distances, the consequences of such conflict can become apparent when individuals arrive at the same food source. To investigate interrelationships between the sexes, we observed successive polar bears visiting a bird breeding colony to feed on clutches of eggs. We found that males succeeded females more frequently and more closely than expected by chance. Moreover, when males were closer to conspecifics, they walked faster, spent less time in the colony and ingested less food. In contrast, female foraging performance was not associated with proximity to other bears. Irrespective of proximity, females generally spent short periods in the colony and ingested fewer clutches than males. Our results suggest that in polar bears, there is a trade-off between the benefits of food intake and the opportunities (in males) and risks (in females) posed by encountering conspecifics. [ABSTRACT FROM AUTHOR]

Birds time their life cycle events to favourable windows in environmental conditions. In tropical environments, where photoperiod variation is small, birds show high variability in the timing of life cycle stages, yet these species have been severely underrepresented in phenology research. Here, we investigated temporal patterns in bird life cycles and resource availability in two sites in tropical Africa: Weppa (Nigeria, 7° N) and Elat (Cameroon, 3° N). In these sites we captured common bulbuls (Pycnonotus barbatus), a widespread generalist, and recorded breeding and moult over a 12‐month period. Simultaneously, we surveyed fruiting tree and arthropod abundance. Our aim was to quantify seasonal patterns in moult and breeding in bulbuls at both sites, and link them to fluctuations in local fruit and arthropod abundance and precipitation. Moult was more seasonal than breeding in both sites, and seasonality of both life cycle events was stronger in Nigeria than Cameroon. The peak timing for moult was 1.5 months earlier in Nigeria than Cameroon. Seasonal variation in abundance of fruiting trees and arthropods was different between sites, as were the associations with breeding and moulting. In Nigeria, we found a positive association between moult and arthropod abundance, and a negative one with fruiting tree abundance. In contrast, in Cameroon moult was associated with higher precipitation, while breeding occurred at times with higher fruit abundance. Our results provide evidence that, even in similar habitats separated by four degrees in latitude, seasonal patterns across three trophic levels are variable. Understanding links between environmental conditions and life cycle events can reveal potential vulnerabilities of tropical species, and guide conservation efforts. [ABSTRACT FROM AUTHOR]

Background: Indigenous village chickens (IVCs) significantly contribute to rural development. There is considerable variation in family flock size and age–sex structure of IVCs. Objectives: This study reports the family flock size, age–sex group structure, and demographic history of IVCs. Methods: This work involved a cross‐sectional study conducted using face‐to‐face general informants' individual interviews with 119 smallholder farmers in highland and lowland agroecological zones. Results: The average family flock size of the sampled households was small (mean = 7.28, range: 1–38). Female birds (hens and pullets) represented the largest proportion of the family flocks (50.2%). The proportion of chicks (26.4%) and pullets (14.4%) was lower than that of hens (35.8%), which creates a considerable challenge in producing replacement breeding flocks. Similarly, the proportion of cockerels (9.1%) was lower than that of cocks (14.3%). The average cock‐to‐hen ratio (one cock to seven hens) was better than the commonly recommended proportion (1 cock to 8–10 hens). As a result, smallholder farmers have not faced the problem of producing infertile eggs. The estimated effective population size (Ne) of 4.02 and the corresponding inbreeding coefficient of 0.12 at the family flock level show that to some extent inbreeding may occur at the family flock level; besides, the estimated Ne represents 55.2% of the census size. However, inbreeding could be offset by the high rate of flock turnover and uncontrolled mating among scavenging birds. Conclusions: Family flocks contain a few birds, which may lead to consanguineous mating. Inbreeding is, however, considerably reduced by uncontrolled breeding among birds that share a common scavenging ground. The driving factors behind the low proportion of chicks and juvenile birds and the family flock size need to be further investigated to improve the contribution of local chickens to rural livelihoods. [ABSTRACT FROM AUTHOR]

Montane species are generally predicted to respond to climate change via upslope movement. Elevational range shifts of birds rarely have been examined in arid regions. Here, we examine shifts in the elevational distributions of breeding birds from two regions of the Great Basin, a desert in the western USA, over 10 to 20 years. We collected data annually from 2001 to 2020, a relatively long and consistent time series that is uncommon in research on distributional shifts. We used single‐species occupancy models of 32 bird species to examine shifts along the full elevational gradient (1650–3200 m a.s.l.) and within the lowest and highest edges (25%) of the gradient. We then conducted simulations to test whether population stochasticity could confound inferences about shifts. We examined whether temperature, precipitation, and primary productivity (normalized difference vegetation index) were associated with occupancy and shifts. The elevational distributions of 23 species shifted, and simulations indicated that shifts in the distributions of 18 species were unlikely to be stochastic. The majority of shifts in the western Great Basin were downslope, whereas those in the central Great Basin were upslope. More shifts occurred at the edges of the elevational gradient than along the full gradient. Elevational shifts lacked a consistent climate‐response signal, but those of some species appeared to follow changes in primary productivity. We found regional differences in elevational shifts and climate associations, and our work suggests that these desert bird populations may be relatively resilient to climate change. [ABSTRACT FROM AUTHOR]

Intensively managed viticulture dominates vast landscapes in the Mediterranean, but considerable vineyard abandonment has been observed over the past two decades. The effect of vineyard abandonment on biodiversity is poorly understood, making it difficult to assess the restoration potential of this common land-use change. We assessed biodiversity responses to vineyard abandonment in Vaucluse, Southern France, using birds as indicator group. We compared bird abundance and diversity in a sample of 64 vineyards, pairing 16 currently managed vineyards with 16 recently abandoned and 16 managed with 16 longer abandoned vineyards. We used mixed models and multivariate techniques to establish relationships between bird diversity and structural attributes of the habitats, and we derived management-specific population densities in a distance sampling approach. Long-abandoned vineyards hosted three times more species and showed a 3.6 times higher total bird abundance than managed viticulture. More recently abandoned vineyards had intermediate species numbers and abundance. Species richness patterns were not modulated by landscape composition and configuration, but higher abundances were found in landscapes with intermediate size of land-cover patches (i.e. field size). In managed vineyards, bird abundances were extremely low, with the exception of Woodlark Lullula arborea , which reached its highest abundance in managed vineyards. The bird community on abandoned vineyards shifted towards forest and woodland shrub species, likely driven by secondary succession, namely shrub encroachment and tree establishment. The strongly positive effects of land abandonment might be due to the fact that only single vineyards (not entire landscapes) were abandoned, thereby increasing habitat heterogeneity at the landscape scale. The future state of the old abandoned vineyards is difficult to predict. As of yet, the abandoned vineyards support a comparably diverse community of breeding birds that reach high abundances in comparison to managed vineyards, within an otherwise impoverished agricultural landscape. [ABSTRACT FROM AUTHOR]

Human-induced disturbance is perceived by avian species as a predation risk. However, the anti-predatory behaviour triggered by these non-lethal events can have negative impacts on reproduction and offspring survival. Research on breeding birds often involves visits to their nests and is likely to disrupt parental behaviour, but nest visits that do not involve direct handling of females have been overlooked as important disturbance events. This study focuses on the impacts of short visits to the nest of incubating Great tit (Parus major) females. We investigated how long they stay away from the nest (off-bout) after a disturbance, their possible compensatory behaviour once they resume incubation (on-bout), and the effects on daily incubation rhythms. We used three years of data from two breeding populations to assess the consequences of disturbances in two scenarios: when the female is present in the nest and flushed, and when the female is absent. We found that after a disturbance, the immediate off-bout was longer when the female was either present or absent, with the magnitude of the disturbance being greater when females were flushed. Females did not compensate with longer on-bouts afterwards, i.e. the research disturbance altered daily incubation behaviour by reducing the total time spent on the nest in relation to the number of daily disturbance events. Females that alter their behaviour in response to perceived predation risk would perform longer incubation periods, resulting in lower hatching rates. These effects of research on female behaviour should be considered when planning field experiments. Significance statement: Incubating birds react to human activity near their nests by changing their behaviour. This may also apply to basic research activities, but we have no data on how a visit, e.g., to check clutch size, affects them. To find out, we classified data from routine research visits to great tit nests, which are often used for research in the wild, into long and short visits. We also considered whether a female was incubating or foraging outside the nest during the visit. We found that females tended to stay away from the nest longer after they encounter a researcher, and after longer visits. Our results show that even slight research activities in the nest alters female incubation behaviour. They flee and leave the clutch unattended for longer, changing the thermal environment of the nest, which is crucial for proper embryo development. [ABSTRACT FROM AUTHOR]

The aim of the current study was to estimate the genetic and environmental parameters for weekly egg weights using a random regression model in wild and white Japanese quails. The base population included 300 wild and white Japanese quails, with a mating ratio of 1:2 (one male with two females). Four mating groups including pure and cross-breeding methods, were considered to produce the next generation. Eggs were collected and numbered based on their sire and dam. At the fifth week of age, 508 female quails were transferred to the laying cages. The data on egg weight was recorded from the seventh to fifteenth week of age. Nine random regression models were analyzed to determine the best orders of Legendre polynomials. The model with first and second-order Legendre polynomials for additive genetic and permanent environmental effects, respectively, indicated the lowest AIC value and was chosen as the appropriate model. The heritability estimates and the ratios of the permanent environment to the phenotypic variance of weekly egg weights ranged from 0.09 to 0.35 and from 0.08 to 0.51, respectively. The effect of permanent environmental factors on the average weight of laid eggs decreased with increasing laying weeks, followed by an increase in the additive genetic effect on the occurrence of this trait. The estimates of genetic and phenotypic correlations between weekly egg weights varied from 0.59 to 0.98 and from 0.21 to 0.51, respectively. As a result, because of higher heritability estimates for later ages, selection to improve weekly egg weight is better performed based on at least the fifth week of the laying period onward. In conclusion, due to high positive genetic correlations among weekly egg weights, the selection basis of each weekly part record can lead to improving the consecutive weekly egg weights. [ABSTRACT FROM AUTHOR]

Humans cooperate to build complex structures with culture-specific architectural styles. However, they are not the only animals to build complex structures nor to have culture. We show that social groups of white-browed sparrow weavers (Plocepasser mahali) build structures (nests for breeding and multiple single-occupant roosts for sleeping) that differ architecturally among groups. Morphological differences are consistent across years and are clear even among groups with territories a few meters apart. These repeatable differences are not explained by among-group variation in local weather conditions, bird size, tree height, or patterns of genetic relatedness. Architectural styles are also robust to the immigration of birds from other groups. [ABSTRACT FROM AUTHOR]

Aerial insectivorous birds breeding in North America have experienced decades of population declines for reasons hypothesized to be related to changes in their insect prey. In agricultural landscapes, land management practices can affect insect communities, leading to concerns that ongoing trends toward more intensive cultivation could affect the ability of farmland-breeding aerial insectivores to forage and provision their offspring with aerial insect prey. To understand how differences in agricultural intensity may affect the foraging behavior of different aerial insectivore species, we used GPS tags to compare the movements and habitat use of 2 species with different foraging ecologies, Hirundo rustica (Barn Swallow) and Tachycineta bicolor (Tree Swallow), breeding at 17 sites in agricultural landscapes in Saskatchewan, Canada. Although we identified differences in foraging behavior consistent with each species' reported ecological traits, including T. bicolor foraging farther and over larger areas than H. rustica , overall foraging behavior was similar between species. Resource selection function analyses indicated that both species used wetlands disproportionately often relative to local wetland availability, especially when detected farther from their nests. Hirundo rustica and T. bicolor both also avoided cropped foraging habitat, using it proportionally less than it was locally available. In landscapes with greater wetland cover, both species selected for wetland habitat more strongly, and among T. bicolor , higher wetland density decreased maximum foraging distance and home range area. In contrast, we found no effect of crop cover on foraging habitat selection or foraging movements. These findings suggest that H. rustica and T. bicolor breeding in Saskatchewan agroecosystems share similar foraging strategies, with wetland habitats appearing to be highly important despite comprising only a small proportion of landscape area. Overall, these results indicate that protecting wetland habitats should be a priority for aerial insectivore conservation in the intensive agricultural landscapes such as the Canadian prairies. [ABSTRACT FROM AUTHOR]

Ireland and Britain are two islands located at Europe's westernmost edge, both of which act as the final breeding outposts for many bird species within their European ranges. Despite their similar geographic locations and geological histories, Ireland and Britain host different breeding avifauna assemblages. Diversity profiles, which can serve as more robust alternatives to classic diversity indices, were employed in this study to explore disparities in the two islands' breeding avifauna assemblages. Variations in assemblages were explored, along with their potential drivers, through analyses at three levels: island‐scale breeding bird assemblage compositions, island‐scale diversity profiles considering 49 common breeding species, and habitat‐specific diversity profiles considering assemblages in east/central Irish farmland and East Anglian farmland. Analysis of the two islands' breeding avifauna assemblages revealed that the Irish assemblage is a complete subset of the British assemblage. Analyses of Irish and British assemblages at both an island scale and a habitat scale revealed patterns linking land use to trends within the two islands' avifauna assemblages. Irish assemblages contained greater proportions of insectivorous farmland species by abundance, while British assemblages contained greater proportions of seed‐eating farmland species; both trends appeared to be related to structural differences in agricultural land use on the two islands. The British and East Anglian assemblages exhibited higher diversity across all analyses, which appeared to be driven by the assemblages' higher relative abundances of species that were most genetically distinct. This study highlights the ability of diversity profiles to impart more information than classic diversity indices by incorporating species similarity data. [ABSTRACT FROM AUTHOR]

When facing challenges, vertebrates activate a hormonal stress response that can dramatically alter behaviour and physiology. Although this response can be costly, conceptual models suggest that it can also recalibrate the stress response system, priming more effective responses to future challenges. Little is known about whether this process occurs in wild animals, particularly in adulthood, and if so, how information about prior experience with stressors is encoded. One potential mechanism is hormonally mediated changes in DNA methylation. We simulated the spikes in corticosterone that accompany a stress response using non‐invasive dosing in tree swallows (Tachycineta bicolor) and monitored the phenotypic effects 1 year later. In a subset of individuals, we characterized DNA methylation using reduced representation bisulfite sequencing shortly after treatment and a year later. The year after treatment, experimental females had stronger negative feedback and initiated breeding earlier—traits that are associated with stress resilience and reproductive performance in our population—and higher baseline corticosterone. We also found that natural variation in corticosterone predicted patterns of DNA methylation. Finally, corticosterone treatment influenced methylation on short (1–2 weeks) and long (1 year) time scales; however, these changes did not have clear links to functional regulation of the stress response. Taken together, our results are consistent with corticosterone‐induced priming of future stress resilience and support DNA methylation as a potential mechanism, but more work is needed to demonstrate functional consequences. Uncovering the mechanisms linking experience with the response to future challenges has implications for understanding the drivers of stress resilience. [ABSTRACT FROM AUTHOR]

Exploring new approaches and methodologies to characterize species distribution dynamics, instead of solely relying on static spatial patterns, should be a priority for species distribution modelling research. Dynamic occupancy models (here, 'dynocc models') are a promising tool to capture temporal patterns of distribution change but their spatial accuracy has been shown to be limited. In this study, we evaluated the effectiveness of incorporating neighborhood connectivity effects into the colonization and extinction functions of dynocc models. To accomplish this, we compared dynocc models accounting either for neighborhood connectivity only, for site‐level habitat covariates only, or combining both neighborhood and habitat explanations in the models for species extinction and colonization. All models were evaluated for a total of 46 bird species typical of forests and shrublands using data at 1 km2 scale from two Catalan breeding bird atlases (CBBA2: 1999–2002 and CBBA3: 2015–2018). Models' predictive performance varied across species between dynocc models incorporating habitat covariates alone and those considering neighborhood connectivity alone. Among species, 68% exhibited a predominant response to habitat effects, 24% showed similar responses for habitat and connectivity effects, and 9% were mostly associated with connectivity effects. Dynocc models combining connectivity and habitat covariates achieved the best predictive performance for most species, with bigger gains for species with similar results from habitat‐only and connectivity‐only models. However, relative performance gains compared to dynocc models using only habitat or connectivity variables were generally modest for most species. This study shows the benefits of considering more spatially explicit formulations in dynocc models, specifically incorporating neighborhood connectivity into the extinction and colonization processes. Our work also highlights the importance of evaluating different model formulations and assessing which aspects of the model are more important depending on the study species. [ABSTRACT FROM AUTHOR]

The spatial scale at which an environmental variable is summarized can have considerable impacts on ecological inference of species distribution and abundance. While several analytical approaches have emerged to determine biologically relevant spatial scales – the spatial scale that most strongly influences the ecological patterns observed – identifying key ecological drivers of scale of effect is still underway. Additionally, several predicted ecological drivers of scale of effect can vary across space and time, but little research on spatiotemporal patterns has occurred. Here, I assessed spatial and temporal variation in scales of effect across 32 North American bird species using 18 years of empirical data from the North American breeding bird survey. Scale estimation was then coupled with trait‐based analyses and hypotheses testing of underlying processes of spatial and temporal variation in scales of effect. All 32 species tested exhibited varied scales of effect across years (average annual scales of effect ranging from 0.2 to 4.97 km) and Bird Conservation Regions (BCR), with spatial variability being the most pronounced. Trait‐based analyses revealed a contrary relationship between hand‐wing index, body size, and scale of effect, though the strength of this relationship was contingent on migratory status. Temporal variation in scales of effect was best explained by changes in human development over time, indicating that avian space use can be explained by an increasing human footprint. Additionally, relative population size, consistent with theoretical predictions stemming from density‐dependent population dynamics, explained notable variation in spatial and temporal scales of effect. These findings contribute to the growing landscape ecology literature by providing empirical evidence for hypothesized drivers of scales of effect. By delineating species‐specific scales of effect and elucidating their ecological drivers, this study enhances our understanding of spatial and temporal scales in ecological processes, aiding conservation efforts in a rapidly changing world. [ABSTRACT FROM AUTHOR]

Offspring sex ratios may deviate from parity when the fitness benefits of producing male or female offspring vary. We tested for sex ratio bias in smooth‐billed anis Crotophaga ani, a communal laying cuckoo with low within‐group relatedness and high offspring dispersal. One male group member performs nocturnal incubation and sires more offspring than other males in the group, suggesting males may have greater reproductive variance than females. We hypothesized that pre‐breeding rainfall influences food availability and offspring sex ratio, predicting that breeding females skew production towards the sex with higher reproductive variance (males) in high food years. Females may also adjust sex ratio across the hatching order to increase survival of the more competitive sex, especially when clutches are larger and within‐brood competition is higher. As adults, male smooth‐billed anis are larger than females, so we assumed male nestlings are more competitive than females and predicted a male‐bias in first hatched chicks in larger broods. Contrary to our first prediction, offspring sex ratio was male biased when pre‐breeding rainfall was lower. In partial support of our second prediction, marginally more first hatched chicks were male in larger broods. To our knowledge, this is the first evidence of offspring sex ratio bias in a communal laying bird species. Future work in this system will attempt to uncover the mechanisms by which co‐breeding females adjust offspring sex ratio and test alternative hypotheses to explain male‐biased offspring sex ratios under different conditions. [ABSTRACT FROM AUTHOR]

Biodiversity is temporally dynamic, reflecting historical environmental conditions and influencing ecosystem stability. Colonisation and extinction dynamics frequently exhibit asynchronous patterns, resulting in net imbalances and thus to long‐lasting richness trends. If these trends are not functionally random, functional net imbalances between colonisations and extinctions (fNICE) are likely to emerge.Using community time series data of European freshwater fish and North American breeding birds, we investigated how fNICE differs from its taxonomic equivalent (tNICE), to provide a comprehensive picture of biodiversity dynamics.Our findings reveal that taxonomic and functional delays are a prevalent feature, challenging the assumption of an immediate response to environmental changes. Taxonomic delays manifest as extinction debts and colonisation credits, while functional delays indicate a shift in the balance between functional gains and losses over time. Moreover, we found that taxonomic and functional imbalances are not always directly correlated, although some specific patterns were found consistently for fish and birds.Early colonisations outpaced functional gains, indicating that although new species arrived earlier than the extinction of other species, the acquisition of new functional traits lagged. Although this may temporarily stabilise communities, as functional redundancy can mitigate loss of function via local extinctions, excessive redundancy can compromise biodiversity's capacity to respond to environmental variations, thereby undermining long‐term resilience.In conclusion, understanding the intricate temporal dynamics of biodiversity responses is paramount for effective conservation practices. While short‐term observations may suggest an equilibrium between diversity and the environmental conditions, our results underscore the importance of considering long‐term dynamics and the interplay between species traits and changing environments. The metrics tNICE and fNICE are valuable tools for quantifying these temporal dynamics and unravelling their consequences for ecosystem stability. Incorporating these insights into conservation strategies can aid in proactively preserving biodiversity and safeguarding the integrity of ecosystems. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

• Flightless steamer ducks preferred nesting on islets and along rocky coasts. • Upland geese preferred nesting in medium-dense shrubland. • Nest detection decreased with denser vegetation. • Invasive mink was present on 100 % of ten islets studied. • Interactive map for designing mink control actions. The introduction of carnivores to islands affects the conservation status of native prey. For two decades, American mink (Neogale vison) has expanded its distribution in the sub-Antarctic archipelago of Austral Patagonia, while preying on nests of solitary ground-nesting birds. Here, upland geese (Chloephaga picta) and flightless steamer ducks (Tachyeres pteneres) are naïve to such predation risk because of the lack of native terrestrial predators. We used nest occupancy models to reveal preferred breeding habitats of those two ground-nesting waterbirds to prioritize areas for future mink control programs. We searched for nests along 80 transects on Navarino Island, southernmost Chile, and 11 transects on 10 nearby islets (3 ± 2.9 ha). Our results showed that islets were essential for breeding in comparison to the main island (5.3 nests/km versus 0.8 nests/km, respectively). The occupancy models revealed that islets were particularly important for flightless steamer ducks, endemic to western Patagonia. As breeding habitat, upland geese preferred medium-dense shrubland, and flightless steamer ducks preferred rocky coastlines. Nest detection was negatively affected by dense vegetation and, in the case of the upland geese, towards the end of the survey. Ten camera traps (n = 385 trap nights) revealed mink presence on all islets, highlighting their capacity to swim in cold water, up to 340 m distance from the main island. We conclude that islets represent breeding refuges for ground-nesting waterbirds and therefore advocate allocating resources for mink control during the warm season on islets. We also provide predictive maps of nesting habitat preference of upland geese and flightless steamer ducks for conservation managers to focus their often scarce human and financial resources on areas critical for breeding. Finally, we argue that detection probability should be an integral part of bird breeding studies, which can be methodologically achieved through targeting transects, not nests, as sample units. [Display omitted] [ABSTRACT FROM AUTHOR]

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The breeding parameters of birds are the key element of bird population monitoring. The assessment of nesting success is difficult in the case of arboreal nests, which are typical for birds of prey. Drones are valuable tools for monitoring arboreal nest occupancy. We tested the feasibility of safely monitoring the common buzzard Buteo buteo and northern goshawk Accipiter gentilis nests via drones. We compared assessments of nest occupancy and the number of fledglings in occupied nests using drones with those obtained from traditional ground-based observations. Additionally, the response of the raptors to drone appearance was documented. The assessments of the nest occupancy of the common buzzard from the ground level and the drone were not significantly different. The monitoring of nest occupation by drones was more precise for northern goshawks. Monitoring using drones showed a higher number of juveniles. Adult birds reacted weakly to the presence of the drone. Our study indicates that monitoring arboreal nests of birds of prey with drones is more effective than monitoring arboreal nests from the ground and does not elicit adverse reactions from the birds. Further studies should be conducted to determine the responses of other raptors. [ABSTRACT FROM AUTHOR]

Simple Summary: Predation is one of the most important factors shaping birds' reproductive strategy. For species nesting in the valley of a large lowland river, flooding is also an additional risk, which can significantly reduce nesting success. During this study, we examined what factors affect the nesting survival of the common sandpiper, a small wader species that inhabits waterbodies, especially rivers. Nests located under shrubs were significantly less predated than nests built in grass. Also, locating nests close to water increases the probability of nesting survival. Predation increases as the breeding season progresses, while nests were most vulnerable to flooding at the beginning of the season. The results obtained in this study provide a better understanding of the factors limiting the nesting success of birds breeding in river valleys and can be the basis for planning conservation measures to increase the nesting success of riverine birds. Predation is an important factor limiting bird populations and is usually the main factor influencing nest survival. In riverine habitats, flooding poses an additional significant challenge. Our study aimed to elucidate the influence of nest location and incubation timing on the survival of common sandpiper nests in a large, semi-natural, lowland river. The survey was carried out in central Poland on the Vistula River, in 2014–2015, 2021, and 2023, along two river sections 2 km and 10 km in length. The nest survival rate was 27%, which is twice as low as that reported on small upland rivers, with flooding being an additional factor causing losses on the Vistula River. Our research showed that mammalian and avian predation accounted for 51% of losses and flooding for 49% of losses. The negative impact of floods on nest survival decreased as the breeding season progressed between May and July, while the chances of being depredated increased during the same period. Nests placed under shrubs were less likely predated than nests located in grass. Moreover, locating the nest in proximity to water increased nesting survival and in fact, more nests found in our study were situated close to the water's edge. [ABSTRACT FROM AUTHOR]

Nesting colonial seabirds are prime examples of central-place foragers, animals that must return to a central location (e.g., a breeding colony) after each bout of foraging. They must balance the costs and benefits of foraging with the need to return to their colonies frequently to form pair bonds during courtship, incubate, provision mates and offspring, and protect and rear young. For some populations, the loss and degradation of suitable breeding habitat due to human activities have necessitated the construction of new breeding sites and/or the restoration of previously occupied sites. South Island, which is part of the Hampton Roads Bridge-Tunnel (HRBT) complex in the Commonwealth of Virginia, U.S.A., is a human-created island that supported Virginia's largest mixed species seabird colony until 2020, when the expansion of the HRBT began and when all nesting seabirds were permanently excluded from the site. We studied the movement patterns of foraging common terns (Sterna hirundo) to determine how travel to and around foraging sites related to their colony location and to inform the siting and construction of a new breeding island. We tracked 18 individual common terns from 07 June to 29 June 2018, and we used a hidden Markov model to assign behavioral states and investigate common tern movements around the HRBT. Common terns spent more than half their time in the colony (58%), followed by time devoted to foraging (22%), and the remainder of their time was spent on outbound (15%) and inbound (5%) transit. Terns traveled as far as 98km from the colony, but on average foraged relatively close to South Island (13.6 ± 0.3km, mean ± 1 SD). Individuals tended to forage in the same locations, but there was variation among individuals. Flying to foraging sites uses energy during the already energetically costly breeding season, thus managers should prioritize placing a new colony site in a location that minimizes the distance traveled to the foraging locations frequented by the South Island birds while accounting for other life-history characteristics. These findings could help in the design and construction of new breeding sites or the restoration of current sites for other, related species, particularly for which these data do not exist. [ABSTRACT FROM AUTHOR]

The distribution of the resources needed by females for reproduction affects their dispersion in space and time, which in turn influences the number of females a male can defend. When males provide parental care they in turn become a resource for females, and influence where females choose to breed. Combined, these factors explain a preponderance of monogamous and (to a lesser extent) polygynous mating systems in birds. However, less frequently observed mating systems in birds remain harder to explain. Here, we analyse the home ranges of male Eclectus parrots (Eclectus roratus) to investigate how their use of space facilitates an unusual polygynandrous mating system (where multiple males mate with multiple females). Female Eclectus parrots in the rainforests of northern Queensland, Australia, have limited movements. They remain at their nest trees for most of the year and rely on multiple wide-ranging males to bring them their food. We used light aircraft and VHF transmitters to track the movements of four male Eclectus parrots during the breeding season. We combined data on home range size with molecular analyses of a larger sample of breeding birds. Our analyses demonstrate that male home ranges overlap with each other and encompass multiple (3–14) trees with nesting females. We show that some males divide their time between, and gain reproductive success with, females up to 7 km apart. Our tracking and molecular data offer insights into how polygynandrous mating systems relate to space use among males and females. [ABSTRACT FROM AUTHOR]

The breeding phenology of birds is often timed to coincide with a peak in food availability. However, the shortening of the vegetation period with increasing elevation may force bird species at high elevations to breed earlier in relation to optimal environmental conditions due to time constraints. We investigated differences in fledging dates in five Alpine woodland songbird species along an elevational gradient from 1500 to 2200 m in Switzerland. We estimated fledging dates from a nationwide citizen science bird monitoring dataset and used the date when the proportion of observations of 'fledged young' reached 50% among all observations indicating breeding behaviour. This measure had the advantage that we could estimate average timing of the broods across a wide geographic range and over many years without the need to search for individual nests. We then compared differences in timing of the broods with climatic conditions and larch budburst across different elevational bands. The daily mean air temperature of 10–15°C was reached 34–38 days later at 2200 m compared to 1500 m, which is a similar delay as found in previous reports on snow melt‐out date. The average delay in larch budburst was 19.2 days at 2200 m compared to 1500 m. In comparison, the average timing of the birds' broods was only 5.4 days later in coal tits and 0.5 days later in Alpine tits at 2200 compared to 1500 m (the two species for which we had the narrowest interval estimates). Also, the estimated delay at higher elevations in the broods of song thrushes, mistle thrushes and Eurasian chaffinches was relatively small. Rather than postponing breeding dates to better environmental conditions later in the season that would match the earlier conditions at low elevation, songbirds breeding at higher elevations may thus have evolved adaptations to cope with the harsher conditions. [ABSTRACT FROM AUTHOR]

The aim of the study is to measure the body weight and beak measurements of the juvenile bald ibis birds breeding in Türkiye and try to find out whether there is a comparative relationship between them and compare them with the measurements in the other studies. In this direction, beak measurements and body weights of total 460 bald ibis chicks, including 197 male chicks and 263 female chicks, were determined in an 11-year period from 2012 to 2022. Average upper beak length was found 15.68 cm, lower beak length was 11.34 cm and average body weight was 1.11 kg in male bald ibis juveniles. Average upper beak length was found to be 15.08 cm, the average lower beak length was 10.84 cm and the average body weight was 1.07 kg in female bald ibis juveniles. A positive and moderate significant relationship was found between upper beak length and body weight (P<0.001). It was determined that the average body weight of male bald ibis juveniles was higher than the body weight of female bald ibis juveniles (P<0.001). Body weight variation could be explained by using only upper beak and lower beak measurement in 26% and 29% respectively. No significant variation was observed in the live weight of bald ibis chicks over the years. [ABSTRACT FROM AUTHOR]

The Egyptian vulture Neophron percnopterus, a medium-sized scavenging bird, is the most-threatened bird species in Italy, with only 10–12 breeding pairs in 2019 distributed in three regions of Southern Italy. With this study, we aim to describe the first documented breeding of Egyptian vulture in Sardinia and to understand which temporal and environmental factors affected its frequentation of a supplementary feeding station. We monitored the nest used during 2019 through direct observations, and the use of the feeding station through camera traps. We fitted a Bayesian Generalised Additive Model to model the effect of the day of the year, the hour of the day, wind direction and wind speed on the presence of Egyptian vulture in a specific hourly time slot at the supplementary feeding station. The chick hatched around 5 July 2019, and it fledged around 21 September. The Egyptian vulture had two peaks of frequentation at the supplementary feeding station: a first one in June, and a second, more important one, between late August and early September. The probability of recording Egyptian vulture peaked between 10:00 and 16:00, and was affected by wind direction, with a slightly higher chance of recording Egyptian vulture when winds came from South-West, West or even North-West, and a lower chance when winds were eastward. This study marks an important step in the conservation of the Egyptian vulture in Italy; it provides an example of spontaneous colonisation, and of the increased attractiveness of the habitat for scavenging birds linked to the actions implemented within a LIFE project. To better target future conservation efforts, it is important to continue with the monitoring and to perform genetic analyses to assess the origin of the individuals. First reproduction of Egyptian vulture in Sardinia. Assessing the effect of the day of the year, the hour of the day, wind direction and wind speed on the probability of presence at a feeding station near the nest. [ABSTRACT FROM AUTHOR]

Caiuajara dobruskii is a tapejarine pterosaur from a unique pterosaur bonebed in southern Brazil, where hundreds of bones referred to this species have been described. Despite its abundance, specimens were found disarticulated and/or disassociated, hindering ontogenetic interpretations from anatomy. Osteohistology is a proper approach to obtain information on ontogeny as well as other palaeobiological information. Here, we analyse 28 thin sections of distinct appendicular bones, from 18 different specimens belonging to Caiuajara dobruskii. All samples display a fibrolamellar microstructure, which suggests that Caiuajara dobruskii had high metabolic rates throughout its life history. We propose five different histology-based ontogenetic stages: Early juvenile; Late juvenile; Juvenile-to-subadult transition; Subadult; and Adult. When compared with other pterosaur ontogenetic series, Caiuajara had a higher bone deposition ratio than other pterosaurs such as Pterodaustro and Rhamphorhynchus, even when compared with the youngest individuals of those taxa. The fact that this bonebed shows a large accumulation of juvenile specimens in this bonebed, whereby adults are rare and senile are absent, suggest that C. dobruskii might have developed similar to some behaviours present in extant birds, as a breeding point and/or creching. [ABSTRACT FROM AUTHOR]

Most migratory birds return every year to the same breeding sites and some species show a similarly high fidelity to wintering grounds as well. Fidelity to stopover sites during migration has been much less studied and is usually found to be lower. Here, we investigate site fidelity and distance to previously visited sites throughout the annual cycle in the common cuckoo, a nocturnal trans‐Saharan migrant, based on satellite‐tracking data from repeated annual migrations of thirteen adult males. All birds (100%) returned to the same breeding grounds, with a median shortest distance of only 1 km from the locations in previous year. This was in strong contrast to a much lower and much less precise site fidelity at non‐breeding sites during the annual cycle: In only 18% of the possible cases in all non‐breeding regions combined, did the cuckoos return to within 50 km of a previously visited non‐breeding site, with no significant differences among the main staging regions (Europe in autumn, Sahel in autumn, wintering in Central Africa, West Africa in spring, Europe in spring). The shortest distance to a previously visited non‐breeding site differed among the staging regions with median shortest distances for the longest stopovers of 131 km [2;1223] (median [min;max]) in Europe, 207 km [1;2222] in Sahel in autumn and 110 km [0;628] in Central Africa. The distance to a previously visited staging site decreased with the time spent at the stopover in a previous year. Understanding the drivers of recurrence and site selection in migratory birds are important for guiding conservation efforts in this group but further studies are needed to establish whether the patterns observed in cuckoos are general among terrestrial migrants with continuous distribution of habitat. [ABSTRACT FROM AUTHOR]

In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species, this pattern is reversed, with more colorful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colorful ornamentation, individual quality and mating success are not well established. Phalaropus fulicarius (Red Phalarope) is a colorful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable color variation. Here, we describe sex differences in color and quantify associations between color variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across 3 consecutive years on the Arctic breeding grounds, we scored color variation for 4 body parts (bill, crown, cheek, and breast), and analyzed scores separately and combined into an overall color score. Females were more colorful and larger than males, and individuals could be unambiguously sexed by crown color. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall color scores. Assortative mating by color was only found for the bill. Color variation did not correlate with plasma testosterone levels, except for male cheek color. Females in better body condition had yellower bills and higher overall color scores, while early-arriving birds had higher breast and overall scores. Phalaropus fulicarius that bred locally were heavier than those that did not, but they did not have higher color scores. Female color variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, P. fulicarius color variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success. [ABSTRACT FROM AUTHOR]

Knowing the location of migratory birds throughout their annual cycle is fundamental for many questions in ornithology. Technological advances have provided several approaches, with increasing miniaturization allowing deployment on smaller and smaller birds. Here, we examine the strengths and limitations of barometric pressure geolocators (pressure tags), which have recently been shown to be extremely effective in tracking small birds (<25 g). The newly developed geolocation by pressure workflow (GeoPressureR) uses a global weather analysis dataset and hidden Markov movement model to reveal locations more accurately or continuously than can be achieved by other available light-weight devices (e.g. light-level geolocators, automated radio telemetry, and archival GPS tags). Additionally, pressure data can provide altitude information and document generally intractable flight behavior, as well as exact migratory phenologies. This new technology can be applied to important unresolved problems such as altitudinal migration, stopover site use, molt migration, vertical airspace use, and drivers of migratory flight initiation, duration, and direction. We provide an example of a pressure tag on a Swainson's Warbler (Limnothlypis swainsonii) deployed on its breeding territory in Virginia, USA, revealing the complete story of its migration to and from Cuba, including its refined wintering site, stopover sites, and migration routes, all with precise timing. Studies relying on pressure tags are still subject to biases related to recovery of the devices for data extraction, and application to birds that exhibit extensive aerial movements (e.g. swallows and swifts) remains challenging. Widespread deployment of pressure tags could show unprecedented details of bird migration and other aspects of aerial behavior, which could benefit conservation and greatly enrich our understanding of avian movement ecology. [ABSTRACT FROM AUTHOR]