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Carrasco, L.; Vera, P.; Belda, E.J., and Monrós, J.S., 2018. Combining remote sensing and field mapping methods to study the vegetation dynamics within a coastal wetland and determine the habitat effects of a threatened bird species (Emberiza schoeniclus witherbyi). Coastal wetlands are highly dynamic changing ecosystems because of the effects of meteorology, wildlife interactions and human activities. They are one of the world's most threatened ecosystems, and threats to them drive the most specialist species to unfavorable conservation status and population trends. Therefore, it is important to frequently monitor the coverage changes of the different vegetation types to understand these species' population dynamics. However, frequent and detailed cartography entails costly efforts. Here, satellite images with field mapping were combined to create vegetation classification maps for past years from SPOT-5 images in the Pego-Oliva coastal wetland (Spain) and obtained classification accuracies above 85%. Together with habitat selection models, this information was used to understand the changes in the habitat of a threatened bird species, the Eastern Iberian reed bunting (Emberiza schoeniclus witherbyi), whose population has sharply declined in recent decades in Spain. A statistically significant reduction in reed–rush patches (positively selected habitat) and an increase in homogeneous reed patches (negatively selected habitat) were observed in those areas where the species disappeared as breeders. This study shows the potential of remote sensing and GIS techniques for the a posteriori monitoring of variation in the habitats available for threatened species to set up management and conservation measures.

In order to describe the influence of Pleistocene glaciations on the genetic structure and demography of a highly mobile, but specialized, passerine, the Savi's Warbler (Locustella luscinioides), mitochondrial DNA sequences (ND2) and microsatellites were analysed in c.330 individuals of 17 breeding and two wintering populations. Phylogenetic, population genetics and coalescent methods were used to describe the genetic structure, determine the timing of the major splits and model the demography of populations. Savi's Warblers split from its sister species c.8 million years ago and have two major haplotype groups that diverged in the early/middle Pleistocene. One of these clades originated in the Balkans and is currently widespread, showing strong evidence for population expansion; whereas the other is restricted to Iberia and remained stable. Microsatellites agreed with a genetic break around the Pyrenees, but showed considerable introgression and a weaker genetic structure. Both genetic markers showed an isolation-by-distance pattern associated with the population expansion of the eastern clade. Breeding populations seem to be segregated at the wintering sites, but results on migratory connectivity are preliminary. Savi's Warbler is the only known migratory bird species in which Iberian birds did not expand beyond the Pyrenees after the last glaciation. Despite the long period of independent evolution of western and eastern populations, complete introgression occurred when these groups met in Iberia. Mitochondrial sequences indicated the existence of refugia-within-refugia in the Iberian Peninsula during the last glacial period, which is surprising given the high dispersal capacity of this species. Plumage differences of eastern subspecies seemed to have evolved recently through natural selection, in agreement with the glacial expansion hypothesis. This study supports the great importance of the Iberian Peninsula and its role for the conservation of genetic variation.

Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance. However, few studies have disentangled the relative importance of these two drivers in causing recent population declines. We quantify the relative importance of both processes by modelling annual variation in population growth of 18 farmland bird species in the UK as a function of measures of land-use intensity and weather. Modelled together, both had similar explanatory power in accounting for annual fluctuations in population growth. When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards. Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.

Many species are currently experiencing anthropogenically driven environmental changes. Among these changes, increasing noise levels are specifically a problem for species relying on acoustic communication. Recent evidence suggests that some species adjust their acoustic signals to man‐made noise. However, it is unknown whether these changes occur through short‐term and reversible adjustments by behavioral plasticity or through long‐term adaptations by evolutionary change. Using behavioral observations and playback experiments, we show that male reed buntings (Emberiza schoeniclus) adjusted their songs immediately, singing at a higher minimum frequency and at a lower rate when noise levels were high. Our data showed that these changes in singing behavior were short‐term adjustments of signal characteristics resulting from behavioral plasticity, rather than a long‐term adaptation. However, more males remained unpaired at a noisy location than at a quiet location throughout the breeding season. Thus, phenotypic plasticity enables individuals to respond to environmental changes, but whether these short‐term adjustments are beneficial remains to be seen.

In spring, many migrating songbirds exhibit protandry (the phenomenon whereby males precede females in arrival at breeding sites). The reed bunting (Emberiza schoeniclus) is a short-distance European migrant which expresses a high degree of protandry and combines both nocturnal and diurnal movements during migrations. In experimental conditions, we studied the proximate mechanisms of protandry and compared locomotor behavior between spring and autumn migrations. We assumed that captive behavior is a proxy for the behavior that birds demonstrate in the wild. Combined, the analysis of seasonal patterns and circadian dynamics of locomotor activity suggested that male reed buntings depart from wintering grounds by daytime flights approximately two weeks earlier than females. Later, they develop nocturnal activity, take off shortly before dawn and continue their flight for several hours in the morning. We argue that such behavior allows males to benefit from both the advantage of nocturnal flight and an efficient start of foraging, thereby reducing the stopover duration (by minimizing search/settling costs) and increasing the total migration speed. In contrast, females express predominantly nocturnal migratory activity in spring. We observed that in spring males had lower fat reserves compared to females. We suggest that males can forage during diurnal movements and therefore do not need to store large energetic reserves. In contrast, in autumn, both sexes display similar patterns of locomotor activity and fat reserves. Overall, our results describe unique sex-specific migratory behaviour and physiology in reed buntings in spring, which, we assume, contribute to spring arrival protandry in this species.Significance statementTo reach their destinations, migratory bird species adopt specific strategies reflected in behavior and/or physiology. In many species, males arrive earlier to the breeding grounds (a phenomenon called protandry). Knowledge of migratory strategies in species that experience both nocturnal and diurnal flights is scarce. To study the mechanisms that lead to protandry in nocturnal/diurnal migrant, we kept reed buntings (Emberiza schoeniclus) under experimental conditions that mimicked changes in photoperiod experienced by free-living birds from autumn migration through wintering to spring migration and recorded the dynamics of their locomotor activity and fat reserves. In spring, we observed sex differences in the seasonal patterns and circadian dynamics of locomotor activity and in the levels of fat reserves. We argue that such sex-related variation in behavior and physiology likely serves as proximate mechanisms for spring arrival protandry in reed buntings.

The reed bunting, Emberiza schoeniclus (Linnaeus 1758), is the only member of the genus adapted to Mediterranean wetlands, where some subspecies are critically endangered. The first complete mitogenome of the eastern Iberian reed bunting (E. s. witherbyi) is presented here and compared with an unpublished mitogenome obtained in northeast Asia (most likely E. s. pyrrhulina). Genetic distance analyses are consistent with the new reed bunting data corresponding to two distinct lineages of E. schoeniclus. A new fossil-calibrated phylogeny suggests that open forest buntings have suffered two rapid speciation events from Late Miocene to Pleistocene, that seem to be correlated with major climatic changes and habitat shifts. Adaptation to a new ecological niche (i.e. wetlands) could have favoured the reed bunting expansion across the Palearctic. The high intraspecific variation observed today could result from the establishment of resident populations within small areas, potentially acting as a climatic refuge.

The decline of farmland birds across Europe is a well‐documented case of biodiversity loss, and despite land stewardship supported by funding from agri‐environment schemes (AES), the negative trends have not yet been reversed. To investigate the contribution of AES towards farmland bird conservation, we compared abundance of five farmland bird species across 13 years and 53 farms (158 farm years = AES, 72 farm years = non AES) in Northeastern Scotland (UK), a region with relatively mixed farmland. Between 2003 and 2015, on both AES and control farms, skylark (Alauda arvensis) showed a nonsignificant decline, and tree sparrow (Passer montanus) and yellowhammer (Emberiza citrinella) nonsignificant increases, whereas reed bunting (Emberiza schoeniclus) and linnet (Carduelis cannabina) populations remained relatively stable. We did not detect a significant association between AES and avian abundance or population trends for any of these species, but there were positive associations with some AES management options. Possible explanations for the lack of a significant AES‐bird abundance association include poor uptake of the best AES options for farmland birds, suboptimal implementation, spill‐over effects from AES onto control farms, and the relatively good state of farmland habitats outwith AES in Northeastern Scotland. Synthesis and applications. We documented a weak effect size of participation in agri‐environment schemes on farmland bird abundance. We therefore recommend future monitoring studies be designed after consulting a power analysis. Among different land management options, we found that species‐rich grasslands, water margins, and wetland creation enhanced breeding bird abundance, highlighting the importance of relatively undisturbed herbaceous or grassland vegetation for farmland conservation. We documented a weak effect size of participation in agri‐environment schemes on farmland bird abundance. We therefore recommend future monitoring studies be designed after consulting a power analysis. Among different land management options, we found that species‐rich grasslands, water margins, and wetland creation enhanced breeding bird abundance, highlighting the importance of relatively undisturbed herbaceous or grassland vegetation for farmland conservation.

An invasion of Roseau cane scale, Nipponaclerda biwakoensis, native to East Asia, is associated with recent widespread dieback of common reed stands in the Mississippi River Delta, Louisiana. A previous study suggested that, in its native range, the combined mortality from Common Reed Bunting Emberiza schoeniclus and parasitoid wasps may control the abundance of Roseau cane scale. However, there is limited knowledge about which other bird species may prey on Roseau cane scale or the feeding patterns of these birds. Here we used web search and citizen science monitoring data to tabulate bird predation events on Roseau cane scales across sites in Japan and determine which bird species may be the most important predators and when the observed feeding typically occurs. We scanned web entries using both Google image searches and the social networking services including Twitter, Instagram, and Facebook. Additionally, we accessed long‐term field observation records obtained by volunteer monitoring conducted by the members of the Kanagawa Branch of the Wild Bird Society of Japan. By using these citizen science approaches, we detected 16 bird species, mainly Common Reed Bunting but also other migratory and resident species, preying on the Roseau cane scale in reed beds throughout central Japan and most detection occurred during the winter. This study demonstrates that biological information obtained from publicly available data from citizen observers can be useful for exploring ecological patterns of various species including potential predators against invasive species.

Wetlands are amongst the richest, yet most threatened types of habitats on Earth. One major threat is the modification of water regime for human activities, which disrupts normal ecosystem equilibrium. In lacustrine wetlands, reduced flooding allows shrubs to take over, ultimately leading to a shift towards woody communities. To counter this, wetland managers have initiated a variety of measures, including mowing, burning, and pasturing. Because of the short time frames of previous studies on the subject, little is known on their potential negative side effects on the ecosystem. Here, we evaluate the long-term effect of mowing on breeding populations of the five most abundant species in our central European study area (the reed warbler Acrocephalus scirpaceus, the common reed bunting Emberiza schoeniclus, Savi’s warbler Locustella luscinioides, the water rail Rallus aquaticus, and the bearded reedling Panurus biarmicus). This study, of an unprecedented time scale (30 years), shows that rotational mowing has no long-term detrimental effects on birds. However, optimal mowing regime for the birds might often be less frequent than what is usually applied. We recommend that mowing be spaced every 3 years at least, and ideally every 6 years or more. We discuss additional measures that could be implemented to complement mowing. Because of the widespread distribution of the target habitat and species, our study provides readily applicable information for wetland managers in Europe and worldwide.

Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection.