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1.
Thomas J. Wood John M. Holland William O. H. Hughes Dave Goulson 《Molecular ecology》2015,24(8):1668-1680
Changes in agricultural practice across Europe and North America have been associated with range contractions and local extinction of bumblebees (Bombus spp.). A number of agri‐environment schemes have been implemented to halt and reverse these declines, predominantly revolving around the provision of additional forage plants. Although it has been demonstrated that these schemes can attract substantial numbers of foraging bumblebees, it remains unclear to what extent they actually increase bumblebee populations. We used standardized transect walks and molecular techniques to compare the size of bumblebee populations between Higher Level Stewardship (HLS) farms implementing pollinator‐friendly schemes and Entry Level Stewardship (ELS) control farms. Bumblebee abundance on the transect walks was significantly higher on HLS farms than ELS farms. Molecular analysis suggested maximum foraging ranges of 566 m for Bombus hortorum, 714 m for B. lapidarius, 363 m for B. pascuorum and 799 m for B. terrestris. Substantial differences in maximum foraging range were found within bumblebee species between farm types. Accounting for foraging range differences, B. hortorum (47 vs 13 nests/km2) and B. lapidarius (45 vs 22 nests/km2) were found to nest at significantly greater densities on HLS farms than ELS farms. There were no significant differences between farm type for B. terrestris (88 vs 38 nests/km2) and B. pascuorum (32 vs 39 nests/km2). Across all bumblebee species, HLS management had a significantly positive effect on bumblebee nest density. These results show that targeted agri‐environment schemes that increase the availability of suitable forage can significantly increase the size of wild bumblebee populations. 相似文献
2.
CATHERINE M. DAVEY JULIET A. VICKERY NIGEL D. BOATMAN DAN E. CHAMBERLAIN HAZEL R. PARRY GAVIN M. SIRIWARDENA 《Ibis》2010,152(3):459-474
Agri‐environment schemes (AES) are central to the conservation of Europe’s farmland biodiversity. The UK Government’s Public Service Agreement target seeks to reverse the decline of farmland birds in England by 2020 through the use of AES. The Entry Level Stewardship (ELS) scheme, introduced in 2005, is the first non‐competitive, broad‐uptake stewardship scheme designed to deliver simple but effective environmental management on farms throughout England. Approximately 5 million hectares of farmland are currently entered into Environmental Stewardship (ES) agreements, and given the scale of this investment it is important to verify the efficacy of ELS as a mechanism for delivering biodiversity benefits. We used spatially referenced ES agreement data to assess the influence of specific management options and combinations of options on farmland bird population changes between 2005 and 2008 derived from standardized surveys carried out on over 2000 lowland farmland 1‐km squares in England. The results showed only limited evidence for short‐term effects of ES. Only Corn Bunting Emberiza calandra and Common Starling Sturnus vulgaris showed some landscape‐specific positive associations with area under ELS management. There was also limited evidence for positive associations between specific management options and the population changes of the species at which they were aimed. The current pattern of option uptake may be limiting benefits of ELS, with boundary management accounting for over 50% of scheme compensation value. However, the time required for option maturation and the time lags in bird population responses to environmental change mean that it is too early to reach definitive conclusions about the success or failure of the scheme. The findings of this study will assist in the development of ELS by feeding into the 5‐year review scheduled for 2010 and have implications for the development of similar schemes elsewhere in Europe. 相似文献
3.
H. Eden W. Cottee‐Jones 《Ecological Management & Restoration》2013,14(1):32-40
As remnant vegetation covers <15% of the Australian sheep‐wheat belt, it is important to identify conservation strategies suitable for use in agricultural landscapes. Tree lines are widespread ecological structures in rural areas, and are now the subject of government subsidy schemes in New South Wales. However, the contribution of tree lines to biodiversity conservation is poorly understood. To identify the conservation value of tree lines, the bird communities in 36 tree lines in Cowra Shire, New South Wales, were surveyed 4 times each. The results demonstrated that tree lines were used by a large number of species, six of which were threatened. Different taxa were associated with different physical tree line attributes, with tree line age an important predictor of species occurrence. While mature tree lines tended to support more species, as was reflected in higher Shannon Diversity Index scores, they also harboured relatively more introduced species and nest predators, while young tree lines provided the best habitat for threatened species. However, these tree lines will mature, and as they do so they will provide increasingly suitable habitat for the hyperaggressive native honeyeater, the Noisy Miner (Manorina melanocephala), and introduced species. Therefore, tree lines in agricultural landscapes may only be serving an important role for conservation on short time scales, and the suite of threatened species young tree lines currently support appear likely to decline further in the future. 相似文献
4.
LORNA J. COLE SARAH BROCKLEHURST DAVID I. McCRACKEN WILLIAM HARRISON DUNCAN ROBERTSON 《Insect Conservation and Diversity》2012,5(1):86-94
Abstract. 1. Riparian field margins (i.e. fenced off areas adjacent to watercourses) are becoming widespread in the UK as a means of mitigating diffuse pollution in intensive grasslands. By providing additional habitats for wildlife, they can potentially enhance farmland biodiversity. This study examined a range of riparian margins to determine their impact on invertebrates. 2. Over a 4‐year period, key invertebrates were monitored by pitfall traps at 69 riparian sites in south‐west Scotland. Riparian margins were classified as open margins (i.e. no fence between the field and watercourse), narrow margins (fences erected within 2.6 m of the watercourse) and wide margins (fences erected over 5 m from the watercourse). Pitfall transects were established at each site in the margin and field. 3. Generalised Linear Mixed Models (GLMMs) were used to model the influence of riparian management and vegetation height on invertebrate activity density. Riparian margins closed to livestock (i.e. wide and narrow margins) had the highest activity densities of Hemiptera, Opiliones, Symphyta larvae and Arionidae, and this could not solely be attributed to differences in vegetation height. For most invertebrate groups, activity density did not differ between wide and narrow margins. Only Linyphiidae, predatory coleopteran larvae and Lumbricidae had higher activity densities in the fields than adjacent riparian margins. 4. The erection of fences along watercourses creates habitat heterogeneity in intensively managed grasslands resulting in enhanced invertebrate populations and thus potentially more prey for foliage gleaning birds. Although margin width did not have a significant influence on invertebrate activity density, wider margins provide a greater area of semi‐natural habitat. 相似文献
5.
Wild bees are declining in intensively farmed regions worldwide, threatening pollination services to flowering crops and wild plants. To halt bee declines, it is essential that conservation actions are based on a mechanistic understanding of how bee species utilize landscapes. We aimed at teasing apart how foraging resources in the landscape through the nesting season affected nesting and reproduction of a solitary bee in a farmland region. We investigated how availability of floral resources and potentially resource‐rich habitats surrounding nests affected nest provisioning and reproduction in the solitary polylectic bee Osmia bicornis. The study was performed in 18 landscape sectors dominated by agriculture, but varying in agricultural intensity in terms of proportion of organic crop fields and seminatural permanent pastures. Pasture‐rich sectors contained more oak (Quercus robur), which pollen analysis showed to be favored forage in early season. More oaks ≤100 m from nests led to higher proportions of oak pollen in nest provisions and increased speed of nest construction in early season, but this effect tapered off as flowering decreased. Late‐season pollen foraging was dominated by buttercup (Ranunculus spp.), common in various noncrop habitats. Foraging trips were longer with more oaks and increased further through the season. The opposite was found for buttercup. Oak and buttercup interacted to explain the number of offspring; buttercup had a positive effect only when the number of oaks was above the mean for the studied sectors. The results show that quality of complex and pasture‐rich landscapes for O. bicornis depends on preserving existing and generating new oak trees. Lignose plants are key early‐season forage resources in agricultural landscapes. Increasing habitat heterogeneity with trees and shrubs and promoting suitable late‐flowering forbs can benefit O. bicornis and other wild bees active in spring and early summer, something which existing agri‐environment schemes seldom target. 相似文献
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7.
Laura M. E. Sutcliffe Pter Batry Urs Kormann Andrs Bldi Lynn V. Dicks Irina Herzon David Kleijn Piotr Tryjanowski Iva Apostolova Raphaël Arlettaz Ainars Aunins Stphanie Aviron Ligita Baleentien&#x; Christina Fischer Lubos Halada Tibor Hartel Aveliina Helm Iordan Hristov Sven D. Jelaska Mitja Kaligari
Johannes Kamp Sebastian Klimek Pille Koorberg Jarmila Kostiukov Anik Kovcs‐Hostynszki Tobias Kuemmerle Christoph Leuschner Regina Lindborg Jacqueline Loos Simona Maccherini Riho Marja Orsolya Mth Inge Paulini Vnia Proena Jos Rey‐Benayas F. Xavier Sans Charlotte Seifert Jaros&#x;aw Stalenga Johannes Timaeus Pter Trk Chris van Swaay Eneli Viik Teja Tscharntke 《Diversity & distributions》2015,21(6):722-730
A large proportion of European biodiversity today depends on habitat provided by low‐intensity farming practices, yet this resource is declining as European agriculture intensifies. Within the European Union, particularly the central and eastern new member states have retained relatively large areas of species‐rich farmland, but despite increased investment in nature conservation here in recent years, farmland biodiversity trends appear to be worsening. Although the high biodiversity value of Central and Eastern European farmland has long been reported, the amount of research in the international literature focused on farmland biodiversity in this region remains comparatively tiny, and measures within the EU Common Agricultural Policy are relatively poorly adapted to support it. In this opinion study, we argue that, 10 years after the accession of the first eastern EU new member states, the continued under‐representation of the low‐intensity farmland in Central and Eastern Europe in the international literature and EU policy is impeding the development of sound, evidence‐based conservation interventions. The biodiversity benefits for Europe of existing low‐intensity farmland, particularly in the central and eastern states, should be harnessed before they are lost. Instead of waiting for species‐rich farmland to further decline, targeted research and monitoring to create locally appropriate conservation strategies for these habitats is needed now. 相似文献
8.
Rochelle A. Fritch Helen Sheridan John A. Finn Stephen McCormack Daire Ó hUallacháin 《Ecology and evolution》2017,7(22):9763-9774
Severe declines in biodiversity have been well documented for many taxonomic groups due to intensification of agricultural practices. Establishment and appropriate management of arable field margins can improve the diversity and abundance of invertebrate groups; however, there is much less research on field margins within grassland systems. Three grassland field margin treatments (fencing off the existing vegetation “fenced”; fencing with rotavation and natural regeneration “rotavated” and; fencing with rotavation and seeding “seeded”) were compared to a grazed control in the adjacent intensively managed pasture. Invertebrates were sampled using emergence traps to investigate species breeding and overwintering within the margins. Using a manipulation experiment, we tested whether the removal of grazing pressure and nutrient inputs would increase the abundance and richness of breeding invertebrates within grassland field margins. We also tested whether field margin establishment treatments, with their different vegetation communities, would change the abundance and richness of breeding invertebrates in the field margins. Exclusion of grazing and nutrient inputs led to increased abundance and richness in nearly all invertebrate groups that we sampled. However, there were more complex effects of field margin establishment treatment on the abundance and richness of invertebrate taxa. Each of the three establishment treatments supported a distinct invertebrate community. The removal of grazing from grassland field margins provided a greater range of overwintering/breeding habitat for invertebrates. We demonstrate the capacity of field margin establishment to increase the abundance and richness in nearly all invertebrate groups in study plots that were located on previously more depauperate areas of intensively managed grassland. These results from grassland field margins provide evidence to support practical actions that can inform Greening (Pillar 1) and agri‐environment measures (Pillar 2) of the Common Agricultural Policy (CAP). Before implementing specific management regimes, the conservation aims of agri‐environment measures should be clarified by defining the target species or taxonomic groups. 相似文献
9.
L G FIRBANK 《The Annals of applied biology》2005,146(2):163-175
Agricultural policy in Europe is changing from supporting production to encouraging environmental benefits in the context of sustainable rural development. As a result, there is a window of opportunity to reconsider the balance between agricultural production and biodiversity management on British farmland, to seek to redress the problems for biodiversity that accrued during intensification without reducing the capacity to meet the coming challenges of global change and population increase. These challenges are discussed in the context of longer term historical change, and in terms of how readily they can be overcome. Current policies can deliver conservation targets that are within the control of individual land managers, and are likely to increase landscape heterogeneity significantly. However, it will be more dif. cult to plan landscapes to deliver agricultural production, ecosystem services and conserve biodiversity in the face of nutrient deposition and climate change. There can be no theoretical “optimum” balance between production and biodiversity, as environmental goals depend greatly upon decisions about scales (from local to global, immediate to long) and the viewpoints of stakeholders. Indeed, the social challenge of delivering sustainable agricultural landscapes is far greater than the scientific one of researching what they might be like. 相似文献
10.
Can ecosystem services be integrated with conservation? A case study of breeding waders on grassland
We review published studies to show that changes in soil moisture levels have significant impacts on a range of wading bird species that use UK lowland grassland, including wet grassland, and obtain their food predominantly by probing the soil. We examine both the hydrological and the ecological literature and assess how management options could alter (1) ecosystem services (via water quality and flooding) and (2) habitat quality for wading birds. The combination of biodiversity goals with broader ecosystem services has been widely advocated and we suggest that appropriate management at multiple scales (e.g. small‐scale: ponds; large‐scale: integrated washlands) could potentially provide both ecosystem services and habitat for wading grassland birds. However, there is only a limited base of evidence on which to assess the potential linkage between these two areas, particularly for non‐wading bird species. Future work should be directed at identifying (1) how crop yield, ecosystem services and biodiversity relate to each other, (2) the extent of land needed to be managed to benefit these multiple purposes and bring about measurable gain (e.g. one or two ponds may make significant inroads in reducing run‐off and pollution but make little difference to wading birds) and (3) solutions to the challenges of setting up management options at large spatial scales (e.g. catchments). 相似文献
11.
Stéphanie Aviron Felix Herzog Iris Klaus Beatrice Schüpbach Philippe Jeanneret 《Restoration Ecology》2011,19(4):500-508
The effects of habitat restoration measures designated to promote farmland biodiversity have been documented at the field scale, but little is known about their role in restoring the agricultural mosaic. In this study, we analyzed the effects of wildflower strips (WFS) at the field scale and in the landscape context on butterflies in a Swiss arable landscape. Three hypotheses were tested: (1) butterfly diversity and abundance are higher in WFS than in conventional fields; (2) butterfly diversity and abundance are enhanced by the amount, proximity and connectivity of WFS in the landscape context; (3) additional factors influence butterfly diversity and abundance according to individual site conditions and landscape context characteristics linked to other landscape elements. WFS had more species and individuals of butterflies than conventional habitats. However, promoted species were mainly generalists; few specialists were enhanced. The diversity of all butterflies and of generalists increased linearly with percent cover of WFS, reflecting an effect of restoration measures depending on the landscape context. The influence of proximity and connectivity of WFS were, however, not significant. The occurrence of specialists was conditioned by plant species richness, while the effect of WFS for overall diversity was affected by the amount of grassland in the surroundings. We conclude that to increase the effectiveness of biodiversity‐orientated restoration measures, their implementation should be steered toward increasing the share of WFS in the landscape. However, the combination of WFS with additional restoration measures might be needed to halt the decline of specialist species. 相似文献
12.
Matthias Albrecht David Kleijn Neal M. Williams Matthias Tschumi Brett R. Blaauw Riccardo Bommarco Alistair J. Campbell Matteo Dainese Francis A. Drummond Martin H. Entling Dominik Ganser G. Arjen de Groot Dave Goulson Heather Grab Hannah Hamilton Felix Herzog Rufus Isaacs Katja Jacot Philippe Jeanneret Mattias Jonsson Eva Knop Claire Kremen Douglas A. Landis Gregory M. Loeb Lorenzo Marini Megan McKerchar Lora Morandin Sonja C. Pfister Simon G. Potts Maj Rundlf Hillary Sardias Amber Sciligo Carsten Thies Teja Tscharntke Eric Venturini Eve Veromann Ines M.G. Vollhardt Felix Wckers Kimiora Ward Andrew Wilby Megan Woltz Steve Wratten Louis Sutter 《Ecology letters》2020,23(10):1488-1498
Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future. 相似文献
13.
Between 1988 and 2007, set‐aside, a European Commission production control measure, took an average of 10% of arable farmland in the EU out of production each year. In 2007, the set‐aside rate was set to 0% and the scheme was later abandoned altogether. By assessing associations of farmland birds with set‐aside and quantifying the extent of set‐aside loss, this study aims to assess the implications of set‐aside loss for farmland bird conservation. During the lifespan of set‐aside, a large number of studies assessed the biodiversity value of set‐aside and other agricultural crops and habitats. Where possible we considered measurable benefits of set‐aside. However, some studies did not specify the type of set‐aside and in some cases set‐aside fields were grouped with cereal stubble fields. In these cases, we took the pragmatic approach of assessing the value of generic stubble fields as a conservative minimum estimate of the value of set‐aside fields. A re‐analysis of data from 30 intensive studies demonstrates that farmland bird densities tended to be higher on set‐aside than on either cereal or oilseed rape crops. Without mitigation, these are the two crops likely to replace most set‐aside fields. We estimate that 26–52% of the farmland populations of key granivorous passerines were present on stubble fields, giving an indication of the proportion of birds likely to be present on set‐aside fields within this broader category. An extensive survey of lowland farmland during winters 1999/2000, 2000/2001 and 2002/2003, repeated in February 2008, showed a doubling of the number of 1‐km squares with no stubble and a halving of the number of squares with more than 10 ha of stubble. After set‐aside abandonment, 72% of squares had no stubble in the important late winter period, confirming that many of the former stubble fields were retained as set‐aside. A simple correlative model suggests that this could cause a small increase in the rate of decline of Skylark Alauda arvensis and Yellowhammer Emberiza citrinella populations, assuming causal links between stubble area and demography. However, even if this assumption cannot be supported, these results clearly indicate that a significant proportion of some farmland bird populations will need to find alternative breeding and foraging habitats. 相似文献
14.
Depin Li Myung‐Bok Lee Wen Xiao Jia Tang Zhengwang Zhang 《Ecology and evolution》2020,10(12):5815-5828
Farmland birds are of conservation concerns around the world. In China, conservation management has focused primarily on natural habitats, whereas little attention has been given to agricultural landscapes. Although agricultural land use is intensive in China, environmental heterogeneity can be highly variable in some regions due to variations in crop and noncrop elements within a landscape. We examined how noncrop heterogeneity, crop heterogeneity, and noncrop features (noncrop vegetation and water body such as open water) influenced species richness and abundance of all birds as well as three functional groups (woodland species, agricultural land species, and agricultural wetland species) in the paddy‐dominated landscapes of Erhai water basin situated in northwest Yunnan, China. Birds, crop, and noncrop vegetation surveys in twenty 1 km × 1 km landscape plots were conducted during the winter season (from 2014 to 2015). The results revealed that bird community compositions were best explained by amounts of noncrop vegetation and compositional heterogeneity of noncrop habitat (Shannon–Wiener index). Both variables also had a positive effect on richness and abundance of woodland species. Richness of agricultural wetland species increased with increasing areas of water bodies within the landscape plot. Richness of total species was also greater in the landscapes characterized by larger areas of water bodies, high proportion of noncrop vegetation, high compositional heterogeneity of noncrop habitat, or small field patches (high crop configurational heterogeneity). Crop compositional heterogeneity did not show significant effects neither on the whole community (all birds) nor on any of the three functional groups considered. These findings suggest that total bird diversity and some functional groups, especially woodland species, would benefit from increases in the proportion of noncrop features such as woody vegetation and water bodies as well as compositional heterogeneity of noncrop features within landscape. 相似文献
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16.
Alexander Argunov Inna Voloshina Damdingiin Bayarlkhagva Baek‐Jun Kim Mi‐Sook Min Hang Lee Kyung Seok Kim 《Ecology and evolution》2016,6(20):7286-7297
Current understanding of phylogeographical structure and genetic diversity of Siberian roe deer remains limited mainly due to small sample size and/or low geographical coverage in previous studies. Published data suggest at least two phylogroups: western (Ural Mountains and Western Siberia) and eastern (east from lake Baikal, including the Korean peninsula), but their phylogenetic relationship remains unclear. Combined sequences of cytochrome b (1140 bp) and the mtDNA control region (963 bp) were analyzed from 219 Siberian roe deer from 12 locations in Russia, Mongolia, and South Korea, which cover a large part of its range, to assess genetic diversity and phylogeographical status. Special emphasis was placed on the demographic history and genetic features of central, peripheral, and isolated populations. Results of median‐joining network and phylogenetic tree analyses indicate that Siberian roe deer from the Urals to the Pacific Ocean are genetically diverse and that geographical distribution and composition of haplogroups coincide with previously described ranges of the subspecies Capreolus pygargus pygargus and Capreolus pygargus tianschanicus. We found that peripheral populations in the northwestern parts of the species range (Urals), as well as the isolated population from Jeju Island, are genetically distinct from those in the core part of the range, both in terms of genetic diversity and quantitative composition of haplogroups. We also found that northwestern (Urals) and northern (Yakutia) peripheral populations share the same haplogroup and fall into the same phylogenetic clade with the isolated population from Jeju Island. This finding sheds light on the taxonomic status of the Jeju Island population and leads to hypotheses about the discordance of morphological and genetic evolution in isolated populations and specific genetic features of peripheral populations. 相似文献
17.
Marie‐Sophie Garcia‐Heras François Mougeot Robert E. Simmons Beatriz Arroyo 《Ibis》2017,159(3):567-579
Understanding variation in food requirements of wild animals is of central importance in population ecology and conservation, as it helps to identify where and when food may be limiting. Studies on diet variation or prey provisioning rates may give useful insights when direct information on prey availability is lacking. We assess spatial and temporal variation in the diet of an endangered predator, the Black Harrier Circus maurus. This raptor is endemic to southern Africa and specializes on small mammals but also feeds on birds and reptiles as alternative prey. Using data on 1679 prey identified in 953 pellets collected in inland and coastal regions from 2006 to 2015, we show that diet composition changed little throughout the breeding season in the coastal region, whereas there was a marked seasonal decline in the occurrence of small mammal prey in the inland region, with a concomitant increase in alternative prey. The proportion of small mammals in the diet declined with increasing maximum temperature, the latter being highest at the inland region late in the breeding season. Using camera recordings at nests in 2014, we further analysed daily patterns of prey provisioning to nestlings. A marked reduction in small mammal provisioning rates occurred during the middle of the day in the hotter inland region but not in the cooler coastal region. Reduced availability of the primary prey, small mammals, in hotter conditions, through a reduction in activity or overall abundance, could explain these patterns. Finally, we show a positive relationship between winter rainfall and interannual differences in the proportion of small mammals in the diet of Black Harriers breeding in the coastal region, suggesting relationships between diet and prey abundance that are mediated through rainfall. We discuss the need to consider spatial variation in food availability in conservation strategies. 相似文献
18.
J. P. Torres‐Florez R. Hucke‐Gaete R. LeDuc A. Lang B. Taylor L. E. Pimper L. Bedriñana‐Romano H. C. Rosenbaum C. C. Figueroa 《Molecular ecology》2014,23(24):5998-6010
Blue whales (Balaenoptera musculus) were among the most intensively exploited species of whales in the world. As a consequence of this intense exploitation, blue whale sightings off the coast of Chile were uncommon by the end of the 20th century. In 2004, a feeding and nursing ground was reported in southern Chile (SCh). With the aim to investigate the genetic identity and relationship of these Chilean blue whales to those in other Southern Hemisphere areas, 60 biopsy samples were collected from blue whales in SCh between 2003 and 2009. These samples were genotyped at seven microsatellite loci and the mitochondrial control region was sequenced, allowing us to identify 52 individuals. To investigate the genetic identity of this suspected remnant population, we compared these 52 individuals to blue whales from Antarctica (ANT, n = 96), Northern Chile (NCh, n = 19) and the eastern tropical Pacific (ETP, n = 31). No significant differentiation in haplotype frequencies (mtDNA) or among genotypes (nDNA) was found between SCh, NCh and ETP, while significant differences were found between those three areas and Antarctica for both the mitochondrial and microsatellite analyses. Our results suggest at least two breeding population units or subspecies exist, which is also supported by other lines of evidence such as morphometrics and acoustics. The lack of differences detected between SCh/NCh/ETP areas supports the hypothesis that eastern South Pacific blue whales are using the ETP area as a possible breeding area. Considering the small population sizes previously reported for the SCh area, additional conservation measures and monitoring of this population should be developed and prioritized. 相似文献
19.
The Common Redshank Tringa totanus breeding population on British saltmarshes has declined by over 50% since 1985, with declines linked to changes in grazing management. Conservation initiatives have encouraged low‐intensity grazing of less than one cattle per hectare, but Redshank have continued to decline, even in regions where light grazing was predominant. This study quantified effects of grazing intensity on Redshank nest survival over six lightly grazed saltmarshes with livestock densities between 0 and 0.82 cattle per hectare, in the Ribble Estuary, northwest England. We assessed whether grazing resulted in nest mortality directly through cattle trampling and/or indirectly through grazer modification of habitat that accelerates predation risks. Cattle density was recorded both during the Redshank breeding season and for 1 year prior to the study, to account for both short‐term trampling effects and the longer term effects on vegetation. Results showed that risk of nest loss to trampling increased from 16% at 0.15 cattle per hectare to 98% at 0.82 cattle per hectare in the breeding season. The risk of a nest being predated increased from 28% with no grazing to 95% at 0.55 cattle per hectare based on all year grazing data. These results suggest that even light conservation grazing at less than one cattle per hectare can reduce Redshank nest survival rates to near zero. It may therefore be appropriate to reduce saltmarsh grazing intensities, or change the timing of saltmarsh grazing to reduce the number of livestock present during the Redshank breeding season. 相似文献
20.
Catherine E. A. Gresty Elizabeth Clare Dion S. Devey Robyn S. Cowan Laszlo Csiba Panagiota Malakasi Owen T. Lewis Katherine J. Willis 《Ecology and evolution》2018,8(15):7574-7587
Floral foraging resources are valuable for pollinator conservation on farmland, and their provision is encouraged by agri‐environment schemes in many countries. Across Europe, wildflower seed mixtures are widely sown on farmland to encourage pollinators, but the extent to which key pollinator groups such as solitary bees exploit and benefit from these resources is unclear. We used high‐throughput sequencing of 164 pollen samples extracted from the brood cells of six common cavity‐nesting solitary bee species (Osmia bicornis, Osmia caerulescens, Megachile versicolor, Megachile ligniseca, Megachile centuncularis and Hylaeus confusus) which are widely distributed across the UK and Europe. We documented their pollen use across 19 farms in southern England, UK, revealing their forage plants and examining the structure of their pollen transport networks. Of the 32 plant species included currently in sown wildflower mixes, 15 were recorded as present within close foraging range of the bees on the study farms, but only Ranunculus acris L. was identified within the pollen samples. Rosa canina L. was the most commonly found of the 23 plant species identified in the pollen samples, suggesting that, in addition to providing a nesting resource for Megachile leafcutter bees, it may be an important forage plant for these species. Higher levels of connectance and nestedness were characteristic of pollen transport networks on farms with abundant floral resources, which may increase resilience to species loss. Our data suggest that plant species promoted currently by agri‐environment schemes are not optimal for solitary bee foraging. If a diverse community of pollinators is to be supported on UK and European farmland, additional species such as R. canina should be encouraged to meet the foraging requirements of solitary bees. 相似文献