534 research outputs found

    Planet Earth II: why most animals can’t hack city living

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    First paragraph: The grand finale of the BBC’s Planet Earth II showcased the ingenious strategies that some animals use to thrive in urban environments. Though impressive, these species are in the minority. As the number of people living in cities around the world continues to rise, we should really be turning our attention to those animals that find city living too hard to handle.  Access this article on The Conversation website: https://theconversation.com/planet-earth-ii-why-most-animals-cant-hack-city-living-6995

    Mitigating the impacts of agriculture on biodiversity: bats and their potential role as bioindicators

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    Agriculture is a dominant land use worldwide with approximately 40% of the land's surface used for farming. In many countries, particularly parts of Europe, this figure is substantially higher and most agricultural land is under intensive practices aimed at maximising the production of food. The intensification and expansion of modern agricultural practices led to the biological simplification of the farmed environment, which has resulted in declines in farmland biodiversity during the last century. As with other taxa, many bat species have suffered severe population declines during the 20th century, with agriculture believed to be one of the main drivers reducing roost availability and foraging habitat. Lower intensity farming methods, and the creation or management of habitat features on farmland could potentially mitigate some of these negative impacts but the effects of this on bats, in comparison to other taxa, have received relatively little attention. Here, I review evidence on the impacts of efforts to increase biodiversity in agricultural landscapes on bat populations, and explore whether responses of bats to agricultural activities are similar to those of other taxa, a necessary requirement if they are to be used as bioindicator species.  There are relatively few studies with which to assess the effects of management interventions on bats in agricultural landscapes, and these are restricted to only a few countries. Nevertheless, there is evidence that bats benefit from lower intensity agricultural systems, specifically organic farming and shaded agroforestry: these systems tend to be associated with higher bat abundance, species richness and diversity, and are more heavily utilised by foraging bats. Whilst very few studies have explicitly tested the utility of bats as bioindicators in agricultural landscapes, overall, the response of bats to lower intensity agricultural systems also reflects responses by other taxa. These studies have been largely restricted to temperate regions, however. The review highlights several major gaps in our knowledge of bats in agricultural landscapes and where future research could be usefully directed including: (1) a broader geographical range of studies examining both the efficacy, and the underlying mechanisms through which lower intensity agricultural systems may benefit bats; (2) the potential for lower intensity systems in key crops such as oil-palm; (3) studies of the demographic effects of conservation management on bats; (4) in order to assess the potential of bats as bioindicators, studies quantifying the response of both bats and other taxa to environmental change in a wider range of biomes and regions are needed

    Location of bumblebee nests is predicted by counts of nest-searching queens

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    1. Bumblebee nests are difficult to find in sufficient numbers for well replicated studies. Counts of nest-searching queens in spring and early summer have been used as an indication of preferred nesting habitat, but this relationship has not yet been validated; high densities of nest-searching queens may indicate habitat with few nesting opportunities (meaning that queens have to spend longer looking for them). 2. From mid April 2010, queen bumblebees were counted along twenty transects in grassland and woodland habitats in Central Scotland, UK. The number of inflorescences of suitable forage plants were also estimated at each transect visit. The area surrounding each transect was searched for nests in the summer. 3. In total 173 queen bumblebees were recorded on transects, and of these 149 were engaged in nest-searching. Searches subsequently revealed 33 bumblebee nests. 4. The number of nest-searching queens on transects was significantly, positively related to the number of nests subsequently found. Estimated floral abundance along the transect did not correlate with numbers of nest-searching queens or the number of nests found, suggesting that queens do not target their searching to areas locally high in spring forage. 5. The data suggest that counts of nest-searching queens do provide a useful positive indication of good nesting habitat, and hence where bumblebee nests are likely to be found later in the year

    The metric matters when assessing diversity: Assessing lepidopteran species richness and diversity in two habitats under different disturbance regimes

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    How we measure diversity can have important implications for understanding the impacts of anthropogenic pressure on ecosystem processes and functioning. Functional diversity quantifies the range and relative abundance of functional traits within a given community and, as such, may provide a more mechanistic understanding of ecosystems. Here, we use a novel approach to examine how lepidopteran richness and diversity, weighted by species abundance, differ between habitats under different disturbance regimes (highly disturbed non‐native plantations and less disturbed broadleaf woodlands), both with and without constraining by similarity due to shared taxonomy or functional traits. Comparisons of diversity between the two habitats differed according to which metric was being used; while species richness was 58% greater in broadleaf woodlands, after accounting for species similarity due to shared functional traits, there was little difference between woodland types under two different disturbance regimes. Functional diversity varied within the landscape but was similar in paired broadleaf and plantation sites, suggesting that landscape rather than local factors drive biotic homogenization in plantation dominated landscapes. The higher richness in broadleaf sites appears to be driven by rare species, which share functional traits with more common species. Moth populations in disturbed, plantation sites represent a reduced subset of moth species compared to broadleaf sites, and may be more vulnerable to disturbance pressures such as clear‐felling operations due to low community resilience

    Negative impacts of felling in exotic spruce plantations on moth diversity mitigated by remnants of deciduous tree cover

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    Moths are a vital ecosystem component and are currently undergoing extensive and severe declines across multiple species, partly attributed to habitat alteration. Although most remaining forest cover in Europe consists of intensively managed plantation woodlands, no studies have examined the influence of management practices on moth communities within plantations. Here, we aimed to determine: (1) how species richness, abundance, diversity of macro and micro moths in commercial conifer plantations respond to management at multiple spatial scales; (2) what the impacts of forest management practices on moth diversity are, and (3) how priority Biodiversity Action Plan (BAP) species respond to management. BAP species were selected as they represent formerly widespread and common species, which have undergone substantial declines in the UK and Europe. We assessed moth communities in three conifer plantations in Northern England and Scotland by light trapping, combining local (e.g. age of planting) and landscape level (e.g. proximity to felled areas) characteristics to evaluate the impacts of forest management on moths. We found no relationship between local factors and moth richness, abundance and diversity but the amount of clear felling in the surrounding landscape had a strongly negative correlation. In contrast, the amount and proximity of broadleaf cover in the surrounding landscape positively influenced macro moth richness and abundance. For six BAP species, abundances were lower close to felled areas but increased with the size of adjacent broadleaf patches. We conclude that clear felling negatively affects moths, probably through alteration of habitats, the loss of larval host plants, and by limiting dispersal. A shift to continuous cover and maintaining broadleaf tree cover within plantations will greatly enhance their value for moth communities

    Flight kinematics of the barn swallow (Hirundo rustica) over a wide range of speeds in a windtunnel

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    Two barn swallows (Hirundo rustica) flying in the Lund wind tunnel were filmed using synchronised high-speed cameras to obtain posterior, ventral and lateral views of the birds in horizontal flapping flight. We investigated wingbeat kinematics, body tilt angle, tail spread and angle of attack at speeds of 4 to 14 ms-1. Wingbeat frequency showed a clear U-shaped relationship with air speed with minima at 8.9 ms-1 (bird #1) and 8.7 ms-1 (bird #2). A method previously used by other authors of estimating the body drag coefficient (CD,par) by obtaining agreement between the calculated minimum power (Vmin) and the observed minimum wingbeat frequency does not appear to be valid in this species, possibly due to upstroke pauses that occur at intermediate and high speeds, causing the apparent wingbeat frequency to be lower. These upstroke pauses represent flap-gliding, possibly a way of adjusting the force generated to the requirements at medium and high speeds, similar to the flap-bound mode of flight in other species. Body tilt angle, tail spread and angle of attack all increase with decreasing speed, thereby providing an additional lift surface and suggesting an important aerodynamic function for the tail at low speeds in forward flight. Results from this study indicate the high plasticity in the wing beat kinematics and use of the tail that birds have available to them in order to adjust the lift and power output required for flight

    Changing spaces: exploring the role of the internet in supporting non-heterosexual youth aged 18-25 in Ireland

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    This study used a sequential qualitatively driven design to explore non-heterosexual internet usage among 18-25 year olds in Ireland. Within the last decade there has been a growing body of research focusing on supporting sexual minority youth in Ireland and understanding their experiences, yet little is known about how they use the internet for support. Non-heterosexual youth can use the internet to access narratives and communities which previously would have required physical presence in geographical places. Considering the role that narrative plays within identity formation, the change this spatial shift has brought about in social relations offers the opportunity for a radical reshaping of both the development of identity and the opportunities for new types of identity to occur in places which they would be unlikely to occur in the past. This study has addressed the gap in literature by positioning a phenomenological sense of place at the centre of the analysis. Using a questionnaire with 126 participants along with 8 in depth narrative based interviews, the study found that non-heterosexual youth perceive the internet as highly valued for its supportive role in identity formation as well the ability to redefine norms and authenticate place for those who experience an absence of offline support

    Sexy streamers? The role of natural and sexual selection in the evolution of hirundine tail streamers

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    In this comment we review some experiments, which address the initial selection pressures promoting the development of tail streamers in some hirundine species. The results of recent experiments have been interpreted as providing evidence for the hypothesis that tail streamers evolved as a handicap, through sexual selection. We offer an alternative explanation with evidence from our studies which suggest that tail streamers may have evolved initially through natural selection for increased manoeuvrability, and would not therefore originally act as a handicap

    Loss of heather moorland in the Scottish uplands: the role of red grouse management

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    Scottish upland moorland dominated by heather Calluna vulgaris is the primary habitat for red grouse Lagopus lagopus scoticus, and has been declining since the 1940s. At the same time red grouse numbers have also fallen. We compared land cover change on sites managed for grouse shooting (1945-1990), and on sites which were managed for grouse in the 1940s but on which management had stopped by the 1980s. Land cover type for sites (N = 229) containing >10% heather cover in the 1940s were examined during the 1940s, 1970s, and 1980s. Grouse management existed on 49% of sites in the 1940s, a number which had fallen to 20% by the 1980s. In the 1940s there were no significant differences in land cover type between areas that were managed for grouse, and areas that were not. However, differences emerged during the 1970s and 1980s; areas where grouse management had ceased by the 1980s showed an expansion in woodland cover from 6% in the 1940s to 30% in the 1980s, and a reduction in heather cover from 53% to 29%. In areas where active grouse management had been maintained, woodland increased from 3% to 10% and heather decreased from 51% to 41% during the same period. These changes may be, in part, a consequence of government agricultural and forestry policy. When profitable, grouse management reduces the attractiveness of such subsidies and thereby results in a slower loss of heathe

    Responses of bats to clear fell harvesting in Sitka Spruce plantations, and implications for wind turbine installation

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    Commercial coniferous plantations are often assumed to be poor habitats for bats. As a result, the impact of forest management practices on bats, such as clear felling, has received little attention, particularly in Europe. However, there is growing evidence from multiple regions that bats do make use of plantation landscapes, and as interest in siting onshore wind turbines in upland conifer plantations grows, there is an urgent need to examine whether felling prior to turbine installation is likely to put foraging bats at risk of collision. In the first study of its kind, we use a “before – after – control – impact” study to explore the short-term impacts of clear fell harvest on bat activity in commercial plantations. Thirty-one mature stands of Sitka Spruce were surveyed using acoustic detectors in three large, upland Sitka Spruce plantations in Britain. Eleven stands were felled between 2013 and 2015, and 26 of the original 31 stands were resurveyed in 2015. The change in total bat activity and species- or genus-specific bat activity was modelled before and after felling occurred at both felled and control stands using generalised linear models. There was no change in overall bat activity at felled sites compared to control sites, but activity ofNyctalusspecies was 23 times higher following felling. TotalPipistrellus spp.activity doubled at felled sites post-harvesting, although this was mainly driven by increased activity at a few felled sites. WhenP. pygmaeusandP. pipistrelluswere considered separately, activity increased slightly but non-significantly. The size of the felled area influenced activity (for bats overall andPipistrellus spp.), with 90% higher activity in smaller felled stands (less than 5ha−1) compared to larger felled stands (greater than 30ha−1). ForP. pipistrellus, activity in felled areas decreased with the duration since harvesting; the greatest activity occurred in stands felled within two months compared to those harvested more than 16months previously. Higher activity for some groups following felling may occur due to the creation of more edge habitat, which is preferred by bothPipistrellusspecies we recorded. An increase in activity following the small-scale felling (‘key-holing’) required for the installation of turbines could put foraging bats at risk from collisions with turbines. Further investigation of the influence of both size of clear fell patch, timing of felling and changes in invertebrate abundance due to felling are required to establish the potential risk of key-holing and turbine installation to foraging bats
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