122 research outputs found

    Pronounced genetic structure and low genetic diversity in European red-billed chough (Pyrrhocorax pyrrhocorax) populations

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    Conservation Genetics August 2015, Volume 16, Issue 4, pp 1011‚Äď1012 Erratum to: Pronounced genetic structure and low genetic diversity in European red-billed chough (Pyrrhocorax pyrrhocorax) populations Erratum to: Conserv Genet (2012) 13:1213‚Äď1230 DOI 10.1007/s10592-012-0366-6 In the original publication, Tables 3 and 6 were published with incorrect estimates of population heterozygosities. All other diversity statistics were correct as originally presented. Updated versions of Tables 3 and 6 with corrected heterozygosity estimates confirmed using Arlequin 3.5 (Excoffier and Lischer 2010) as in D√°vila et al. (2014) are provided in this erratum. Discrepancies were minor for populations on the British Isles. The correct estimates for Spain are slightly larger than those reported for La Palma by D√°vila et al. (2014), but this does not necessarily affect their interpretation that choughs on La Palma may have originated from multiple migration events. The original conclusion that chough populations on the British Isles have low genetic diversity compared to continental European populations remains and is now, in fact, strengthened.Peer reviewedPostprin

    Tourism in protected areas can threaten wild populations: from individual response to population viability of the chough Pyrrhocorax pyrrhocorax

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    International audienceMany protected areas are now faced with increasing pressure from visitors and tourism development. There is thus an urgent need for conservation biologists to evaluate the full impact of human disturbance not only on individual responses but also on the viability of protected populations so that relevant management measures can be proposed. We studied the impact of tourism on the rare and endangered chough Pyrrhocorax pyrrhocorax on a protected french island to assess the relationship between visitor pressure, bird individual behavior and fitness, and population viability. During 8 years, we monitored foraging behavior and estimated monthly juvenile survival using mark-recapture data. Population viability was examined under different tourism scenarios, using a stochastic individual-based model that incorporated the impact of visitor numbers on juvenile survival. In summer, the foraging probability of choughs was negatively correlated with the number of visitors. As a result, the time allocated to foraging during peak tourist season, adjusted to day length and prey availability, was 50% lower than expected. Juvenile survival rates were lowest in August, the peak tourist season, and varied significantly across years. August survival rate and therefore annual survival were negatively correlated with the number of visitors on the island in August and, except for a minor negative effect of rainfall, were not influenced by other environmental variables. Sthochastic simulations predicted a low probability of extinction of the protected population if the number of visitors remains constant in the future. However, short-term viability would be dramatically reduced if the current rate of increase in visitor numbers is maintained. We show that a relatively minor human-induced disturbance (e.g. scaring individuals away) has dramatic effects on population viability in a protected area, even when breeding individuals are not directly affected. This suggests that the full impact of tourism in protected areas may be overlooked, and has direct consequences for the assessment of sustainable levels of human distrurbance and the design of quantitative management options compatible with tourist activities in protected areas. We specifically emphasize the need for more integrative approaches combining research at individual and population levels

    Plant and spider communities benefit differently from the presence of planted hedgerows in highway verges

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    International audienceRoad verges should play a crucial role as a refuge for native flora and fauna in human dominated landscapes. However, the influence of construction choices, such as plantation of woody species, on the biodiversity supported by roadsides has received little attention, although the presence of hedgerows in roadsides is likely to enhance their role as a refuge, notably for woodland species. Using standardised methods, we assessed the impact of planted hedgerows on two taxonomic groups (plants and spiders) inhabiting highway verges within an intensive agricultural landscape. We examined community richness, taxonomic and functional composition in sites with and without planted hedgerows. At the site level, the response of plant and spider communities to the presence of planted hedgerows differed markedly: hedgerows were associated with significantly higher plant richness (higher őĪ-diversity), but similar spider richness. Plant communities in sites without hedgerows appeared as a subset of communities in sites with hedgerows, whereas spider communities in non-planted sites were complementary to that of planted sites (increased ő≤-diversity). The presence of planted hedgerows was also associated with increased taxonomic and functional trait diversity at the landscape level (ő≥-diversity), through an increased ő≤-diversity in both plants and spiders. Our results thus suggest that a mosaic of planted hedgerows and grassland habitats is crucial for the maintenance of biodiversity at a landscape scale. By providing information for road practitioners and policy makers regarding their potential impact on biodiversity, these results have important direct implications for the management of road networks

    Cons√©quences sur l'avifaune terrestre de l'√ģle de Trielen (r√©serve naturelle d'Iroise, Bretagne) de l'√©radication du Rat surmulot (Rattus norvegicus)

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    The Norwegian Rat (Rattus norvegicus) invaded the Trielen Island (Iroise Natural Reserve, Brittany, France) during the beginning of the XXth century and was eradicated in 1996. Breeding pairs of all terrestrial bird species were censused annually, from 1996 before the eradication operation to 2001. None of the 7 occasional breeding species (two being a priori exposed to Norwegian Rat predation) established as a regular breeder after the eradication operation. On the other hand, numbers of breeding pairs increased by a factor of 1.7 to 2.0 for the Dunnock (Prunella modularis), 2.2 to 2.7 for the Wren (Troglodytes troglodytes), and 5.5 to 7.0 for the Rock Pipit (Anthus petrosus). Many biological facts converged to identify the rodent disappearance as the major driving factor of these increases. This Norwegian Rat eradication was particularly pertinent as a biological conservation operation, because of its positive effect on the local Rock Pipit (Anthus petrosus) population as the French coast hosts near 50 % of the subspecies petrosus world population. The 2001 Trielen Island abundance index (26 to 46 breeding pairs per coastal km) was among the highest known ones for that species. The large and quick increase following the disappearance of the Norwegian Rat showed the high sensibility of the Rock Pipit to mammalian predationL'inventaire du nombre de couples nicheurs du peuplement d'oiseaux terrestres de l'√ģle de Trielen (R√©serve Naturelle d'Iroise, Bretagne) a √©t√© r√©alis√© annuellement entre 1996 et 2001, suite √† l'√©radication, en 1996, de la population du Rat surmulot (Rattus norvegicus) install√©e sur l'√ģle depuis le d√©but du XXe si√®cle. La disparition du rongeur ne s'est accompagn√©e, ni d'apparition o√Ļ de disparition d'esp√®ces, ni de la p√©rennisation de la reproduction de 7 esp√®ces r√©put√©es nicher occasionnellement sur le site, deux d'entre elles √©tant a priori vuln√©rables au comportement de pr√©dation exerc√© par le Surmulot. Les effectifs de couples nicheurs de l'Accenteur mouchet (Prunella modularis), du Troglodyte mignon (Troglodytes troglodytes), et du Pipit maritime (Anthus petrosus), esp√®ces a priori toutes vuln√©rables au comportement de pr√©dation du rongeur, ont √©t√© multipli√©s respectivement par un facteur de 1,7 √† 2,0, de 2,2 √† 2,7 et de 5,5 √† 7,0. Les faits convergent pour d√©signer l'√©radication du rongeur comme le facteur de causalit√© majeur de ces augmentations. Cette op√©ration qui rel√®ve de la biologie de la conservation est particuli√®rement pertinente vis-√†-vis du Pipit maritime dont le lin√©aire c√ītier fran√ßais accueille pr√®s de 50 % de la population mondiale de la sous-esp√®ce petrosus. L'indice d'abondance relev√© en 2001 sur l'√ģle de Trielen (26 √† 46 couples nicheurs par km de lin√©aire c√ītier) compte parmi les plus √©lev√©s connus √† ce jour pour l'esp√®ce. Son fort accroissement, suite √† la disparition du Surmulot, t√©moigne de la sensibilit√© de l'esp√®ce √† la pr√©dation mammalienne

    DIET AND FUELLING OF THE GLOBALLY THREATENED AQUATIC WARBLER ACROCEPHALUS 1 PALUDICOLA AT AUTUMN MIGRATION STOPOVER AS COMPARED WITH TWO CONGENERS

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    International audienceThe effective conservation of aquatic warbler (Acrocephalus paludicola), one of the most threatened western Palaearctic migratory passerines, requires good knowledge of its ecological needs at stopover sites. In particular, identifying its diet, which controls the accumulation of fat reserves during migration, facilitates the selection and management of adequately protected areas. Further key information includes the relationship between prey species abundance and habitats of aquatic warbler on stopover. We performed standardised mist-netting in the Audierne marshes (western France) during 12 years, which resulted in the capture of 1,200 aquatic warblers, and provided measurements for mass gain and the collection of faeces to infer the birds’ diet. Invertebrate sampling was carried out in the three main Audierne marshhabitats(reedbed, fen mire and meadow). In order to go beyond prey digestibility bias,we also studied two closely related Acrocephalusspecies, present at migration stopover sites during the same period. We found that the diet composition of aquatic warbler observed at migration stopover sites is based on large-sizedprey (Odonata, Orthoptera, Lepidoptera).Likes edge warblers, aquatic warblers put on weight during migration stopovers (daily mass gain =0.38g). This increase in weight suggests that the aquatic warblers might have adopted a strategy for long-distance migration with few stopovers only. Due to great differences in diet, conservation management for the threatened aquatic warbler at stopover sites should not rely on existing knowledge abouts edge and reed warblers. Similarities in the diet of aquatic warbler between nesting areas and migration stopover areas and the relationship between habitat and prey abundance suggest that fen mires play an important role in the quality of the for aging habitat at stopover site

    Acoustic activity of bats at power lines correlates with relative humidity: a potential role for corona discharges

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    With the ever-increasing dependency on electric power, electrical grid networks are expanding worldwide. Bats exhibit a wide diversity of foraging and flight behaviours, and their sensitivity to anthropogenic stressors suggests this group is very likely to be affected by power lines in a myriad of ways. Yet the effects of power lines on bats remains unknown. Here we assessed the responses of insectivorous bats to very high voltage power lines (VHVPL; greater than 220 kV). We implemented a paired sampling design and monitored bats acoustically at 25 pairs, one pair consisting of one forest edge near to VHVPL matched with one control forest edge. Relative humidity mediates the effects of power lines on bats: we detected bat attraction to VHVPL at high relative humidity levels and avoidance of VHVPL by bats at low relative humidity levels. We argue that the former could be explained by insect attraction to the light emitted by VHVPL owing to corona discharges while the latter may be owing to the physical presence of pylons/cables at foraging height and/or because of electromagnetic fields. Our work highlights the response of bats to power lines at foraging habitats, providing new insight into the interactions between power lines and biodiversity

    Acoustic activity of bats at power lines correlates with relative humidity: a potential role for corona discharges

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    With the ever-increasing dependency on electric power, electrical grid networks are expanding worldwide. Bats exhibit a wide diversity of foraging and flight behaviours, and their sensitivity to anthropogenic stressors suggests this group is very likely to be affected by power lines in a myriad of ways. Yet the effects of power lines on bats remains unknown. Here we assessed the responses of insectivorous bats to very high voltage power lines (VHVPL; greater than 220 kV). We implemented a paired sampling design and monitored bats acoustically at 25 pairs, one pair consisting of one forest edge near to VHVPL matched with one control forest edge. Relative humidity mediates the effects of power lines on bats: we detected bat attraction to VHVPL at high relative humidity levels and avoidance of VHVPL by bats at low relative humidity levels. We argue that the former could be explained by insect attraction to the light emitted by VHVPL owing to corona discharges while the latter may be owing to the physical presence of pylons/cables at foraging height and/or because of electromagnetic fields. Our work highlights the response of bats to power lines at foraging habitats, providing new insight into the interactions between power lines and biodiversity

    Articulating citizen science, semi-automatic identification and free web services for long-term acoustic monitoring: examples from France and UK

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    Monitoring biodiversity over large spatial and temporal scales is crucial for assessing the impact of global changes and environmental mitigation measures. Bats often have high conservation prioritisation owing to their trophic position, habitat associations and threat level, and many have dedicated management plans. However, poor knowledge of species' ecology, identification issues and surveying challenges mean that large-scale monitoring to produce required distribution and abundance information is less developed than for some other taxa. Exciting possibilities applicable to professional and citizen science are offered by new recording techniques and methods of semi-automated species recognition based on sound detection. Static detectors deployed to record bats throughout whole nights have been recommended for standardised acoustic monitoring but until recently cost and lack of software to support the analyses of such data has prohibited wide uptake. Such monitoring schemes have recently been deployed in both Britain and France allowing the fast and standardized collection of millions of bat records together with very interesting data on non-targeted taxa such as bush-crickets. Such data management led us to develop generic and open tools: (1) the Tadarida software toolbox providing a generic detection and classification of sound events, and (2) an open dedicated web portal (www.vigiechiro.herokuapp.com) to allow participants to manage and upload their data, then being processed trough Tadarida to get a quick feedback on the content of the data. We demonstrate how such data can accurately describe pronounced ecological patterns for numerous species at different scales: spatial variation in activity as a proxy for relative abundance, habitat selection and phenology of seasonal and nocturnal activity. If maintained in the long term, such schemes will also greatly improve estimates of species temporal trends and hence the assessment of conservation priorities. The feedback produced by these two monitoring schemes allows us the opportunity to provide recommendations for the sustainability of long-term acoustic monitoring of bats. These include a database that is adaptively managed to allow all raw data to be re-analysed every time automatic identification makes significant progress, while keeping the link with expert validation to ensure consistency in the semi-automated process. More importantly, there are real benefits of developing long-term acoustic monitoring within a collaborative framework. Specifically, (1) for collaboration among bat scientists for the collection of reference sound data, because diversity and quantity of the reference library remains a limiting factor for automatic identification, and (2) for work on bats to consider the wider acoustic monitoring of other species groups by working with other zoologists to share resources and costs

    Stopover ecology of autumn-migrating Bluethroats (Luscinia svecica) in a highly anthropogenic river basin

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    Wetlands are highly productive habitats used by many avian species as stopover sites during their migrations. However, these habitats are highly threatened by anthropogenic activities, such as land-use changes, the introduction of exotic species, and global warming. Further understanding on the spatiotemporal use of wetlands and their surrounding areas by migrating birds is essential to predict how these changes might affect avian en route ecology. We selected a habitat-generalist passerine, the Bluethroat Luscinia svecica, as model of how migratory birds exploit a highly anthropogenic river basin in southwestern France (i.e. Barthes de la Nive) during autumn migration. We captured and radiotracked 29 young Bluethroats in this region to shed light on different aspects of their stopover ecology and behavior such as stopover duration, habitat selection, and home-range size. We also characterized Bluethroat diet and arthropod availability in different habitats. Bluethroats positively selected pure or mixed reed beds (associated with sedge), hydrophilous tall grasslands, and corn crops. Birds staying more than one day, 8.4 days on average, used preferably corn crops. Home-range sizes were on average 5.8 ha (fixed kernels K95) and high-occupancy area (K50) was 1.36 ha with large individual variation. Bluethroats stopping over with low fuel loads tended to have larger home ranges and used preferentially corn crops, wet, or mesotrophic grasslands and rural paths. Reed beds were typically used as roosting habitat for the majority of birds, being on average 397 m apart from their daytime core areas. Short-staying birds tended to show higher fuel loads and restricted their activities to a smaller home range (1 ha) in pure and mixed reed beds. The diet of Bluethroats was dominated by ants, spiders, and beetles that were particularly abundant in corn crops. The use of corn crops by autumn-migrating Bluethroats in our study site seems to be a reasonable solution in a highly altered environment. Reducing the use of insecticides in these crops and delaying the harvesting time after mid-October are two supplemental measures that, together with a good management of the remaining wetland patches, could greatly favor Bluethroats and other migratory species in this region
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