We aimed to describe the morphologic and isotopic differences of European Goldfinches Carduelis carduelis according to their migratory behaviour or geographic origin. We compared morphologic and isotopic variables between birds caught in two different obligatory migratory pathways (eastern and western border of the Pyrenees) and throughout the post-breeding period (from late summer to winter). The isotopic and morphological traits varied across seasons (from autumn to winter), indicating that birds captured later in the season had traits typical of longer-distance migrants that come from regions situated further north. Moreover, our results suggest that Goldfinches caught in the eastern and western borders of the Pyrenees slightly differ in body size and in one of the two colour patch-associated traits, but not in their flight apparatus or isotopic values, these last being more strongly related to their areas of origin. Such observed regional differences, therefore, may be more strongly related to other selection pressures.

The growth pattern of an organism is influenced by multiple factors, such as its sex, parental investment, food abundance and sibling competition. For species showing sexual size dimorphism, the sex of siblings is expected to affect the growth of nestlings through differences in competitive hierarchies mediated by an asymmetry in body size. This study describes growth curves of Ryukyu Scops Owl Otus elegans nestlings, based on the analysis of body mass, wing length and tarsus length in 99 individuals. We subsequently tested for effects of sex of the nestlings, having an older male sibling, hatching order and brood size on the growth curves. Overall, we detected significant effects of several predictor variables, although differences between groups were often small. Males and later hatched chicks had lower body mass throughout their growth. The smaller the brood, the heavier the chicks were on days 0–1 and 30–32, although this relationship was reversed on days 8–13. Males and later hatched chicks also had shorter wings. Males had shorter tarsi than females from day 0 to day 4, however, dimorphism in this trait was reversed afterwards. Chicks in a large brood had longer tarsi. Earlier hatched chicks had longer tarsi in the first half of the growth period, but some of this difference had disappeared by the second half. From day 0 to day 3, individuals with an older brother had longer tarsi than those with an older sister. However, halfway through the growth period and thereafter, individuals with an older brother had shorter tarsi than those with an older sister. The fact that older brothers had an effect on the tarsus growth of their siblings was not due to sexual body size asymmetry, as in fact males were smaller than females in wing length and body size. We suggest that sexual differences in aggression mediated by androgens may have played a role.

The Chiffchaff superspecies complex occupies almost the entire Palearctic and includes many taxa of different ranks. It is traditionally considered to be one of the most complex problems in the taxonomy of Palearctic birds. We present new data on the genetics, morphology and bioacoustics of the Chiffchaff taxa found in Turkey, the Caucasus, Transcaucasia and Kopet Dagh: ‘greenish' brevirostris, caucasicus, menzbieri and ‘brownish' lorenzii. In southern Turkey, two Chiffchaffs were identified which carried a novel haplotype, recently discovered in Northern Israel. Both individuals from Turkey looked somewhat brighter and more yellowish than typical brevirostris, but their song clearly corresponded to the brevirostris dialect. The form brevirostris, inhabiting the western and central regions of Northern Turkey, was found to be the most distinct among all ‘greenish’ taxa, due to its small body size, wing formula and distinct vocal dialect. Paradoxically, the mitochondrial DNA of brevirostris is almost identical with caucasicus, whereas, in this respect, menzbieri is different from both. We believe that this paradox can be explained if we suppose that caucasicus originated during the ancient hybridization of brevirostris and menzbieri. The relationships between brevirostris and lorenzii, in the mountainous regions of eastern Turkey, show the mismatch between phenotypic and genotypic traits in some individuals that could also be a result of hybridization.

Understanding spatiotemporal dynamics in wildlife populations is of paramount importance for their effective conservation, however longitudinal studies are relatively scarce for most animal groups. Waterbirds are an exception however, since midwinter surveys have been implemented in most areas of the world for over four decades. The Dalmatian Pelican Pelecanus crispus is a globally threatened emblematic wetland species of the Palearctic, with a wide distribution in Europe and Asia. Its global population is divided into three distinct groups that coincide with the Black Sea-Mediterranean Flyway, the Central Asian Flyway and the East Asian Flyway. In this study we used International Waterfowl Census data to assess long-term changes in the wintering population of the Dalmatian Pelican pertaining to the Black Sea-Mediterranean Flyway. We report national and regional population trends in SE Europe and Turkey and explore spatiotemporal patterns in the wintering numbers and distribution of the species in relation to climate variability during the last two decades. Our key findings suggest that during the past 30 years the abundance of wintering Pelicans increased across the entire study area. Within the eastern subpopulation this increase was most accentuated in the northern edge of the species' wintering distribution, which was associated with a local warming trend, and was coupled with a north-eastern shift in the distribution pattern, yet not driven by climate conditions. Other contributing factors, such as winter site fidelity, local food availability, finer scale climatic and habitat conditions, but also carry-over effects should be considered in future studies. Given the advancement of first laying dates in Dalmatian Pelicans in almost all breeding sites and the strict timing of IWC counts, we also propose the implementation of species-specific winter surveys, independently from IWC, to obtain a more thorough understanding of the dynamics of the Dalmatian Pelican's wintering population.

Rock Nuthatches comprise two morphologically similar species: Western Rock Nuthatch Sitta neumayer and Eastern Rock Nuthatch Sitta tephronota, with several subspecies within each species. These two species are closely related, and the two together are often considered an offshoot of the Sitta europaea group. The Western Rock Nuthatch is distributed across the Balkans to the Caucasus and Iran while the Eastern Rock Nuthatch is distributed across Eastern Anatolia, Iran, Afghanistan, Turkmenistan and Tajikistan. Using partial mitochondrial ND2 and ND3 gene sequences from populations throughout the distribution ranges and ecological niche modelling, we investigated the genetic structure and biogeographic history of these bird species. Two well-differentiated and supported clades in each species indicated a reciprocal monophyly with no gene flow between birds in the Zagros Mountains and other populations. Ecological niche modelling suggested population contraction in their potential habitat during the Last Glacial Maximum. The genetic differentiation in Zagros Mountains indicates that the post-glacial colonization of most of the Rock Nuthatch distribution range occurred from refugia located elsewhere than the Zagros Mountains. Given that Rock Nuthatches in the Zagros Mountains have long constituted an isolated population, there may be two phylogenetic species within each Rock Nuthatch species. Further genetic studies should be performed for taxonomic clarification.

Rice fields have traditionally been considered key feeding grounds for many waterbird species, including herons. Studies show that field management and flooding cycles influence the reproductive parameters of these birds. L'Albufera de València, on the east coast of the Iberian Peninsula, has large areas of rice fields and is home to the third largest breeding colony of herons in Spain. Changes in water and rice field management that have occurred since the colony was last assessed (1990) may have affected the colony's reproductive performance. Clutch and brood size, and hatching, nesting and breeding success were estimated for Grey Heron Ardea cinerea, Purple Heron Ardea purpurea, Cattle Egret Bubulcus ibis, Little Egret Egretta garzetta, Squacco Heron Ardeola ralloides (Ardeidae) and Glossy Ibis Plegadis falcinellus (Threskiornithidae) in 2015–2017. The extent of flooding and cultivation of rice fields was assessed from February 2016 to June 2017. Reproductive parameters were related to the state of the rice fields. All reproductive output parameters were lower than those reported in the literature. In 2016, laying started earlier (at the end of April), when the fields were still dry and hatching started from May, after flooding. In 2017, peak hatching occurred in June, when the fields were sown. A significant relationship was found between breeding success and the area of sown fields, except for the Squacco Heron. We found that birds that initiated egg laying closer to the date of flooding had a relatively higher breeding success for the Little Egret, Glossy Ibis, Cattle Egret and Purple Heron. The success of nesting populations in this type of artificial wetland requires water management plans that synchronize flooding regimes and maintenance of flooded areas with the biological requirements of these species.

Avian species have a variety of antipredator strategies in response to predator threats of different levels. Mobbing behaviour is most common in colonial birds, although the defensive behaviour and interspecific relationships in mixed-species colonies composed of non-mobbing species are still unclear. In a mixed-species colony of Great Cormorants Phalacrocorax carbo and Grey Herons Ardea cinerea, we investigated defensive responses to potential avian predators and to actual avian predators. Our observations revealed that the birds distinguished between potential predators and reacted to particular predator species that could prey on large birds. Moreover, we found that the two colonial species showed different defensive antipredator behaviours: Herons exhibited aggressively defensive behaviours; whereas Cormorants, though vigilant, remained on the nest. To our knowledge this is the first report to suggest the possibility of commensalism in the Phalacrocoracidae, whereby Great Cormorants benefit from the defensive behaviour of Grey Herons.

Stress may be defined as a change in the homeostasis of an individual. However, if long-lasting, stress may produce significant detrimental effects to individuals, such as increasing the susceptibility to haemosporidian parasites. Therefore, we aimed to study whether and how stress and body condition predict the probability of hosts having haemosporidian parasites and increased parasite load. We captured birds in an area of Cerrado stricto sensu in southeastern Brazil and used microscopy techniques to assess haematological parameters, as well as infections by protozoans, and confirmed all infections using nested PCR. We used the heterophil/lymphocyte ratio and global leucocytes as a proxy of individual stress and the scaled mass index as a body condition metric. We captured 68 individuals from five bird species: Ruddy Ground-dove Columbina talpacoti, Great Kiskadee Pitangus sulphuratus, Lesser Elaenia Elaenia chiriquensis, Flavescent Warbler Myiothlypis flaveola and Brown-crested Flycatcher Myiarchus tyrannulus. We did not find support for parasite prevalence being predicted by body condition or haematological variables. However, we found that birds with a higher heterophil/lymphocyte ratio, lower body condition and lower global leukocyte count, were more likely to have a higher parasite load (haemosporidian parasitaemia). Our results suggest that birds with chronic stress and poor health may be more susceptible to greater infection intensity and/or recrudescence episodes by malarial parasites due to previous immunosuppression.

Northeast India, located in a global biodiversity hotspot, faces several biodiversity issues. These include shorter fallow periods between ‘jhum’ (shifting cultivation) cycles which give less time for forests to recoup, along with encroachment, logging and other developmental activities. This is leading to widespread habitat loss and degradation. In such a scenario, Community Reserves that largely make up the Protected Area network in Northeast India could likely act as refugia for several species. Our study explored how owls use these Reserves in the Garo Hills in Meghalaya. We conducted three temporal replicates in thirty-three 500 × 500 m grids between January and March 2020. Ecologically relevant site and sampling covariates were quantified in each grid along with owl counts. Occupancy and N-mixture models revealed that wind speed, temperature, humidity and survey start time had the greatest effect on the detection probability of owls. On the other hand, occupancy and abundance were most influenced by slope, distance to water body, disturbance and tree structural characteristics (girth and tree height heterogeneity). With these findings, we highlight the importance of preserving water bodies and old-growth forests in Community Reserves of the Garo Hills landscape, which seem to be acting as refugia for the Brown Wood-owl Strix leptogrammica, an old-growth forest specialist thought to be currently in decline.

We describe a vocal signal and associated postures shown by Eurasian Spoonbills Platalea leucorodia leucorodia just before the departure of (part of) the flock from a site, but also occurring in flight. Onomatopoetically called ‘ook’, it is a soft muffled sound that was noticed in Spoonbills at a stopover site during southward migration in southwestern France and at a post-breeding feeding site in The Netherlands. When making the ‘ook’-sounds, adults as well as juveniles contributed to what looked like dialogues, the sound of the juvenile having a higher pitch than that of the adult. On the basis of their specific occurrence in pre-departure contexts, we propose that the vocalizations function during collective decision-making, perhaps contributing to reach consensus before and during non-routine group movements from one place to another.

In the central Monte desert in Argentina, feeding site selection by seed-eating birds and their high abundance associated with the presence of trees (particularly Algarrobos Prosopis flexuosa) are well known patterns during the breeding season, but these associations disappear during autumn and winter. In order to understand habitat selection by these bird species, we assessed the importance of Algarrobos during the defence and establishment of breeding territories in the open Algarrobo woodland of the central Monte desert for the three most common resident seed-eating birds: Ringed Warbling-finch Microspingus torquatus, Many-coloured Chaco Finch Saltatricula multicolor and Rufous-collared Sparrow Zonotrichia capensis. Despite some ecological differences between the species (e.g. nest site selection, feeding behaviour) all of them selected Algarrobos as song posts. Height, density and spatial configuration of these trees were features associated with the selection of territories. The patterns of selection we found at previously unexplored spatial scales (territory and within-territory) and associated with territorial defence, provided plausible explanations to seasonal shifts in the space use reported for central Monte desert seed-eating birds and highlight the close link between central Monte desert avifauna and Algarrobos. As in many arid regions, tall scattered trees are keystone features of the central Monte desert and management plans should be implemented in order to stop the current degradation and loss of these arid woodlands.

The feeding ecology and distribution of the Common Kingfisher Alcedo atthis has been extensively studied during the breeding season in European freshwater habitats, but there is much less known about the ecology of this species in marine and brackish habitats. This study aims to (1) document the presence of Common Kingfishers in marine habitats of Galicia (NW Spain), based on a database of bird sightings collected in mainland Galicia (2004–2020) and on the Cíes Islands (Coast of Galicia; 2008–2019), and (2) study their diet in marine habitats, analyzing 17 pellets collected during autumn and winter in a coastal salt lagoon on the Cíes Islands. During autumn and winter, the number of observations of the species in mainland Galicia were higher in marine habitats than in freshwater habitats (χ²₁ = 10.88, P < 0.001). Moreover, Common Kingfishers visit the Cíes Islands mostly during autumn and winter (98.6% of observations). Both datasets show that marine habitats are very important for wintering birds. In the coastal lagoon on the Cíes Islands, the Common Prawn Palaemon serratus was the most frequent prey (41.7%), accounting for the highest percentage of the total biomass (68%); much more than the second most frequent prey, gobies (Gobiidae; 35.5%). This finding is exceptional in Europe, since only a few studies report shrimp as a prey item for Common Kingfishers, probably due to the lack of data from marine habitats during winter.