Heather Moorland Research Articles

Land-use-based freshwater sediment source fingerprinting using hydrogen isotope compositions of long-chain fatty acids

Rapidly changing land use patterns and frequent extreme weather events have resulted in an increased sediment flux to freshwater systems globally, highlighting the need for land-use-based sediment source fingerprinting. Application of variability in hydrogen isotope compositions (δ2H values) of vegetation-specific biomarkers from soils and sediments is relatively underexplored for land-use-based freshwater suspended sediment (SS) source fingerprinting, but has the potential to complement the information from routinely applied carbon isotope analysis and provide new insights. We analysed δ2H values of long-chain fatty acids (LCFAs) as vegetation-specific biomarkers in source soils and SS collected from the mixed land use Tarland catchment (74 km2) in NE Scotland, to identify stream SS sources and quantify their contributions to SS. Plant growth form was the primary control on source soils LCFAs (n-C26:0, n-C28:0, n-C30:0) δ2H variability, while the isotopic composition of source water had no significant control. Forest and heather moorland soils covered with dicotyledonous and gymnosperm species were differentiated from arable land and grasslands soils covered with monocotyledonous species. SS samples collected for fourteen months from the Tarland catchment with a nested sampling approach showed monocot-based land use (cereal crops, grassland) to be the major source of SS with 71 ± 11% contribution on catchment-wide scale averaged throughout the sampling period. Storm events after a dry summer period and sustained high flow conditions in the streams during autumn and early winter suggested enhanced connectivity of more distant forest and heather moorland land uses covering relatively steep topography. This was shown by an increased contribution (44 ± 8%) on catchment-wide scale from dicot and gymnosperm-based land uses during the corresponding period. Our study demonstrated successful application of vegetation-specificity in δ2H values of LCFAs for land-use-based freshwater SS source fingerprinting in a mesoscale catchment where δ2H values of LCFAs were primarily controlled by plant growth forms.

Highest densities of mountain hares (Lepus timidus) associated with ecologically restored bog but not grouse moorland management.

Over the last 20 years, ecological restoration of degraded habitats has become common in conservation practice. Mountain hares (Lepus timidus scoticus) were surveyed during 2017–2021 using 830 km of line transects in the Peak District National Park, England. Historically degraded bog areas were previously reported having low hare numbers. Following bog restoration, we found hare densities of 32.6 individuals km−2, notably higher than neighboring degraded (unrestored) bog with 24.4 hares km−2. Hare density on restored peatland was 2.7 times higher than on bogs managed for grouse shooting at 12.2 hares km−2 and 3.3 times higher than on heather moorland managed for grouse shooting at 10.0 hares km−2. Yearly estimates varied most on habitats managed for grouse, perhaps indicative of the impact of habitat management, for example, heather burning and/or possible hare culling to control potential tick‐borne louping ill virus in gamebirds. Acid grassland used for sheep farming had a similar density to grouse moorland at 11.8 hares km−2. Unmanaged dwarf shrub heath had the lowest density at 4.8 hares km−2. Hare populations are characterized by significant yearly fluctuations, those in the study area increasing by 60% between 2017 and 2018 before declining by ca. 15% by 2020 and remaining stable to 2021. During an earlier survey in 2002, total abundance throughout the Peak District National Park was estimated at 3361 (95% CI: 2431–4612) hares. The present study estimated 3562 (2291–5624) hares suggesting a stable population over the last two decades despite fluctuations likely influenced by weather and anthropogenic factors. Mountain hares in the Peak District favored bog habitats and were associated with restored peatland habitat. Wildlife management should be cognizant of hare density variation between habitats, which may have implications for local extinction risk.

A response to Hesford & MacLeod (2022): Rejection of a model estimating high densities of mountain hares in the Peak District, England.

A recent Game and Wildlife Conservation Trust (GWCT) report (Hesford & MacLeod 2022) suggested densities of mountain hares (Lepus timidus) may reach 52 - 125/km2 in parts of the Peak District, England. These are notably higher than previous and current estimates of 5 - 33 hares/km2 (Matthews et al. 2018; Bedson et al. 2022). We review Hesford & MacLeod (2022) who based their methods on those used in a review of mountain hare survey methods in Scotland (Newey et al. 2018). This review demonstrated a weak, non-significant relationship between hare encounter rates using spotlight surveys of walked transects at night and estimated densities derived from spatial capture-recapture (SCR) methods on managed heather moorland (p=0.08). Newey et al. (2018) recommended that this relationship should not be used to estimate hare densities. We reproduce the Newey et al. (2018) linear model and confirm its poor predictive ability and show that removal of one outlier reduces an already marginal relationship to a near-flat line (p=0.80). Hesford & MacLeod (2022), nonetheless, used this relationship to estimate hare densities along non-randomly placed transects. We conclude that reportedly high mountain hare densities estimated by Hesford & MacLeod (2022) are biased and based on a model with little predictive power; more recent Distance Sampling estimates are from 37 - 96% lower (Bedson et al. 2022). It is important that wildlife monitoring methods robustly account for survey bias and error, detection probability and variation between habitats, especially if results are to inform potential population management interventions.

The diel activity pattern of mountain hare (Lepus timidus) on managed heather moorland in Scotland.

The research presented in this paper provides an insight into the behavioral ecology of mountain hares on heather moorland in the Lammermuir Hills of southeast Scotland. We examine the seasonal and diel activity patterns using camera traps over a period of 12 months. The rate of camera detections was calculated for the different divisions of the 24‐hr cycle (daylight, dusk, night, and dawn). During autumn and winter (October–February), the activity pattern was crepuscular with greater activity at dusk than at dawn. Daylight activity was relatively low, and there was a regular pattern of small peaks of activity during the night. In spring and summer (March–September), peaks of crepuscular activity remained evident but daylight activity was much more prevalent than during autumn and winter, and night activity was lower. We discuss the problematic definition of twilight and present an explanation for seasonal changes in the pattern of diel activity that is linked to the reproductive cycle of the mountain hare.

The Impacts of Recolonisation of an Urbanised River by Native and Non-native Species

The roles of native and non-native species in the recolonisation of the River Don in South Yorkshire, England, are considered through the lens of environmental history. Notable as one of the most polluted river systems in Western Europe, the Don-Dearne-Rother catchment runs west to east from South Yorkshire and North Derbyshire and drains a significance part of middle England. However, from their origins in the foothills of the high Pennine hills with peat-bogs and heather moorland, the constituent rivers run through upland-fringe farmland and then into the major urban and industrial centres of the region. By the mid-twentieth century the reaches of these watercourses were grossly polluted and physically degraded too. However, from the 1970s onward there began a slow recovery in environmental quality and this has continued to the present day. This paper focuses on the ecological changes in the main urban zones of the River Don catchment and includes the constituent rivers namely the Sheaf, the Porter, the Rother, the Dearne, the Rivelin, and the Loxley. Importantly, though conservationists may be reluctant to accept it, the new ecology which has emerged throughout the catchment is irreparably changed from that of the seventeenth and eighteenth centuries. That landscape itself was already majorly altered from the countryside described in the Domesday account of 1086, and that too was much changed from the Romano-British landscape of a millennium earlier. The landscape is changing and is permanently changed and so too is the ecology that it now supports. In this context, a hybrid or recombinant ecology has been observed to develop through the process of eco-fusion and is made up of an intimate mix of native and non-native species.

Compound-specific isotope analysis with nested sampling approach detects spatial and temporal variability in the sources of suspended sediments in a Scottish mesoscale catchment

Intensification of land use is a primary cause of increased suspended sediment load in freshwater systems, hence land-use-specific sediment source tracing is necessary to inform sustainable land and water management. Here we tested the application of compound-specific isotope analysis (CSIA) of vegetation biomarkers to fingerprint suspended sediment sources from the mesoscale agricultural Tarland catchment (74 km2) in NE Scotland. Our aim was to test a parsimonious nested sampling approach from a headwater sub-catchment to apportion suspended sediment sources across headwater to catchment-wide scales. Compound-specific carbon isotopic signatures (δ13C) of long-chain fatty acids (LCFAs) from source soils were able to successfully distinguish between forest, heather moorland, permanent grassland, and arable land cover. Permanent grassland was a prominent source of sediment at both headwater and catchment scales, with an annual average contribution of 79% and 56%, respectively, indicating grazing pressure and runoff via preferential pathways. Increased sediment input from arable land at the catchment scale (40%) compared to the headwater sub-catchment (18%) indicated land use intensification in lowland areas. Forest and heather moorland contributed marginally to suspended sediments (~2%), despite covering 43% area of the catchment area. Temporal variability of sediment sources observed over fourteen months (May 2017 – June 2018) showed a higher relative contribution from arable land during summer and autumn and a higher contribution from permanent grassland during winter and spring, likely linked to seasonality of rainfall and agronomic activities.These results demonstrate a successful use of δ13C values of LCFAs to quantify land-use-specific suspended sediment sources. Comparison of two suspended sediment techniques showed usefulness of time-integrated mass samplers for representative and cost-effective sampling. We recommend that future nested sampling designs should include spatially distributed source soil tracer characterization covering the whole catchment area to reduce the uncertainty in sediment source attribution from headwaters to the catchment outlet.

Tree planting in organic soils does not result in net carbon sequestration on decadal timescales.

Tree planting is increasingly being proposed as a strategy to combat climate change through carbon (C) sequestration in tree biomass. However, total ecosystem C storage that includes soil organic C (SOC) must be considered to determine whether planting trees for climate change mitigation results in increased C storage. We show that planting two native tree species (Betula pubescens and Pinus sylvestris), of widespread Eurasian distribution, onto heather (Calluna vulgaris) moorland with podzolic and peaty podzolic soils in Scotland, did not lead to an increase in net ecosystem C stock 12 or 39years after planting. Plots with trees had greater soil respiration and lower SOC in organic soil horizons than heather control plots. The decline in SOC cancelled out the increment in C stocks in tree biomass on decadal timescales. At all four experimental sites sampled, there was no net gain in ecosystem C stocks 12-39years after afforestation-indeed we found a net ecosystem C loss in one of four sites with deciduous B. pubescens stands; no net gain in ecosystem C at three sites planted with B. pubescens; and no net gain at additional stands of P. sylvestris. We hypothesize that altered mycorrhizal communities and autotrophic C inputs have led to positive 'priming' of soil organic matter, resulting in SOC loss, constraining the benefits of tree planting for ecosystem C sequestration. The results are of direct relevance to current policies, which promote tree planting on the assumption that this will increase net ecosystem C storage and contribute to climate change mitigation. Ecosystem-level biogeochemistry and C fluxes must be better quantified and understood before we can be assured that large-scale tree planting in regions with considerable pre-existing SOC stocks will have the intended policy and climate change mitigation outcomes.

Differential responses of heather and red grouse to long-term spatio-temporal variation in sheep grazing

During the last century, afforestation and intensification of sheep grazing in the British uplands have led to widespread declines in globally rare heather moorland. We quantified changes in heather cover over 70 years in relation to changes in sheep grazing on Langholm Moor, and examined the impact on red grouse, a gamebird inhabiting heather moorland. Between 1948 and 2009, when grazed heavily by sheep, heather-dominated vegetation declined from 53 to 14% cover. Large-scale sheep reductions from 2011 then allowed increase of heather-dominated vegetation cover to 18% by 2015. However, changes in heather cover were associated with changes in grouse abundance only where heather-dominated cover was reduced below thresholds of 27% (95% CL 18–36%; pre-breeding) and 17% (95% CL 13–20%; post-breeding). The number of grouse shot between 1951 and 1992 remained high where 37–65% of dominant heather cover was retained, but then declined between 1992 and 1996 following increased predation by raptors, leading to the cessation of shooting. Subsequently, grouse densities fluctuated in relation to periodic management by gamekeepers (1992–1999 and 2008–2016), but heather loss continued possibly until 2011, and predation in this context prevented sustained increases sufficient for ‘driven’ shooting. Grouse shooting provides an economic incentive to maintain and restore heather moorland. On Langholm Moor, however, afforestation in the surrounding landscape and isolation from other heather moors may have led to a grouse population less well buffered against growing predation pressure, especially outside keepered periods. As grouse shooting could not be restored, the future management of the moor remains uncertain.

Cotula alpina (Asteraceae) naturalised in the British Isles

Cotula alpina (Hook f.) Hook f. is an Australian herb that has been naturalised in Britain since the 1970s and is now locally abundant in parts of northern England and northwest Scotland. Its method of arrival is unknown but it is likely to have originated from gardens and perhaps also from wool shoddy. It appears to be spreading rapidly due to high seed production and effective dispersal by sheep, humans and vehicles and is now locally abundant on moorland tracks and in adjacent acid grassland and heather moorland managed for grouse. Due to its evergreen and mat-forming habit it can outcompete community dominants such as Agrostis capillaris and Festuca ovina in areas where levels of grazing are high. It appears to be well suited to the British climate and is therefore likely to spread into similar habitats in other regions where it could pose a threat to localized species associated with short grassland on acidic soils. Its overall abundance and ability to regenerate rapidly from seed means it is unlikely to be easily controlled or eradicated, although exclusion of grazing may help to reduce its abundance in some areas.

Long-term changes in the abundance and breeding success of raptors and ravens in periods of varying management of a Scottish grouse moor

Management of heather moorland for driven Red Grouse (Lagopus lagopus scotica) shooting in the British uplands may benefit some raptors by reducing predation risk, especially when breeding, and by increasing food availability. We describe changes in abundance and breeding success of four raptor species and Common Raven (Corvus corax) during a 27-year study on a grouse moor in southwest Scotland in relation to whether or not the moor was managed by gamekeepers. Ground-nesting raptors, Hen Harrier (Circus cyaneus) and Merlin (Falco columbarius), increased during periods of grouse moor management and had a higher proportion of successful nesting attempts. Predation was the main apparent cause of breeding failure. In contrast, grouse moor management did not influence either abundance or breeding success of tree- and crag-nesting species, i.e., Peregrine (Falco peregrinus), Common Buzzard (Buteo buteo), and Raven. Buzzard sightings increased during the study, in line with their national recovery, whereas Peregrine and Raven showed little change in abundance. The results of our study highlight that management for Red Grouse can benefit both Hen Harrier and Merlin. However, on a UK scale these benefits to Hen Harriers, but not Merlin, are outweighed by their illegal killing, caused by fears that their consumption of Red Grouse can undermine the economics of grouse moor management.

Using repeat electrical resistivity surveys to assess heterogeneity in soil moisture dynamics under contrasting vegetation types

As the relationship between vegetation and soil moisture is complex and reciprocal, there is a need to understand how spatial patterns in soil moisture influence the distribution of vegetation, and how the structure of vegetation canopies and root networks regulates the partitioning of precipitation. Spatial patterns of soil moisture are often difficult to visualise as usually, soil moisture is measured at point scales, and often difficult to extrapolate. Here, we address the difficulties in collecting large amounts of spatial soil moisture data through a study combining plot- and transect-scale electrical resistivity tomography (ERT) surveys to estimate soil moisture in a 3.2 km2 upland catchment in the Scottish Highlands. The aim was to assess the spatio-temporal variability in soil moisture under Scots pine forest (Pinus sylvestris) and heather moorland shrubs (Calluna vulgaris); the two dominant vegetation types in the Scottish Highlands. The study focussed on one year of fortnightly ERT surveys. The surveyed resistivity data was inverted and Archie’s law was used to calculate volumetric soil moisture by estimating parameters and comparing against field measured data. Results showed that spatial soil moisture patterns were more heterogeneous in the forest site, as were patterns of wetting and drying, which can be linked to vegetation distribution and canopy structure. The heather site showed a less heterogeneous response to wetting and drying, reflecting the more uniform vegetation cover of the shrubs. Comparing soil moisture temporal variability during growing and non-growing seasons revealed further contrasts: under the heather there was little change in soil moisture during the growing season. Greatest changes in the forest were in areas where the trees were concentrated reflecting water uptake and canopy partitioning. Such differences have implications for climate and land use changes; increased forest cover can lead to greater spatial variability, greater growing season temporal variability, and reduced levels of soil moisture, whilst projected decreasing summer precipitation may alter the feedbacks between soil moisture and vegetation water use and increase growing season soil moisture deficits.

Influence of forest and shrub canopies on precipitation partitioning and isotopic signatures

AbstractOver a 4‐month summer period, we monitored how forest (Pinus sylvestris) and heather moorland (Calluna spp. and Erica spp.) vegetation canopies altered the volume and isotopic composition of net precipitation (NP) in a southern boreal landscape in northern Scotland. During that summer period, interception losses were relatively high and higher under forests compared to moorland (46% of gross rainfall [GR] compared with 35%, respectively). Throughfall (TF) volumes exhibited marked spatial variability in forests, depending upon local canopy density, but were more evenly distributed under heather moorland. In the forest stands, stemflow was a relatively small canopy flow path accounting for only 0.9–1.6% of NP and only substantial in larger events. Overall, the isotopic composition of NP was not markedly affected by canopy interactions; temporal variation of stable water isotopes in TF closely corresponded to that of GR with differences of TF‐GR being −0.52‰ for δ2H and −0.14‰ for δ18O for forests and 0.29‰ for δ2H and −0.04‰ for δ18O for heather moorland. These differences were close to, or within, analytical precision of isotope determination, though the greater differences under forest were statistically significant. Evidence for evaporative fractionation was generally restricted to low rainfall volumes in low intensity events, though at times, subtle effects of liquid–vapour moisture exchange and/or selective transmission though canopies were evident. Fractionation and other effects were more evident in stemflow but only marked in smaller events. The study confirmed earlier work that increased forest cover in the Scottish Highlands will likely cause an increase in interception and green water fluxes at the expenses of blue water fluxes to streams. However, the low‐energy, humid environment means that isotopic changes during such interactions will only have a minor overall effect on the isotopic composition of NP.

Long-term trends in abundance and breeding success of red grouse and hen harriers in relation to changing management of a Scottish grouse moor

Large areas of heather moorland in the British uplands are managed for shooting red grouse Lagopus lagopus scotica. However, there has been a long-standing conflict between grouse moor management and the conservation of raptors, particularly the hen harrier Circus cyaneus. Langholm Moor, a grouse moor in southwest Scotland, has hosted studies aiming to resolve this conflict for 24 years. Between 1992 and 1997, whilst managed as a grouse moor, hen harrier numbers increased from two to 20 breeding females, and raptor predation removed large proportions of both adult grouse and chicks. As driven shooting was no longer viable, grouse moor management ceased in 1999, and was not restored until 2008. This paper considers how cessation and subsequent restoration of grouse moor management, which involved heather management and legal control of generalist predators, affected the abundance and breeding success of red grouse and hen harrier, as well as the abundance of their perceived key predators; red fox Vulpes vu...

Numerical and functional responses of Common Buzzards Buteo buteo to prey abundance on a Scottish grouse moor

Predators will often respond to reductions in preferred prey by switching to alternative prey resources. However, this may not apply to all alternative prey groups in patchy landscapes. We investigated the demographic and aggregative numerical and functional responses of Common Buzzards Buteo buteo in relation to variations in prey abundance on a moor managed for Red Grouse Lagopus lagopus scotica in south‐west Scotland over three consecutive breeding and non‐breeding seasons. We predicted that predation of Red Grouse by Buzzards would increase when abundance of their preferred Field Vole Microtus agrestis prey declined. As vole abundance fluctuated, Buzzards responded functionally by eating voles in relation to their abundance, but they did not respond demographically in terms of either breeding success or density. During a vole crash year, Buzzards selected a wider range of prey typical of enclosed farmland habitats found on the moorland edge but fewer Grouse from the heather moorland. During a vole peak year, prey remains suggested a linear relationship between Grouse density and the number of Grouse eaten (a Type 1 functional response), which was not evident in either intermediate or vole crash years. Buzzard foraging intensity varied between years as vole abundance fluctuated, and foraging intensity declined with increasing heather cover. Our findings did not support the prediction that predation of Red Grouse would increase when vole abundance was low. Instead, they suggest that Buzzards predated Grouse incidentally while hunting for voles, which may increase when vole abundances are high through promoting foraging in heather moorland habitats where Grouse are more numerous. Our results suggest that declines in their main prey may not result in increased predation of all alternative prey groups when predators inhabit patchy landscapes. We suggest that when investigating predator diet and impacts on prey, knowledge of all resources and habitats that are available to predators is important.

Ascertaining the nature and timing of mire degradation: using palaeoecology to assist future conservation management in Northern England

Large areas of upland mire and moorland in Northwest Europe are regarded as degraded, not actively peat-forming, and releasing carbon. Conservation agencies have short-term targets to restore such areas, but often have no clear knowledge of the timing and nature of degradation. It has been suggested that palaeoecology can be used to inform conservation management about past vegetation states, so as to help identify feasible restoration targets. Our research study in northern England, commissioned by the national statutory conservation agency, applied multiple palaeoecological techniques to establish the vegetation history of several mire and moorland sites, specifically to ascertain the nature and timing of degradation. Techniques applied included pollen analysis, plant macrofossil and charcoal analyses, determination of peat humification and mineral magnetic susceptibility, with ages ascertained using spheroidal carbonaceous particle analysis, 210Pb and 14C dating. Data are presented from case-study sites in the North York Moors, North- and South Pennines to illustrate how palaeoecology can extend long-term monitoring and guide conservation management. Palaeoecological data from a site within a National Nature Reserve, subject to exceptionally long-term (half-centennial) ecological monitoring, showed that this period does not include its pre-degradation state and that its current valued vegetation is novel and may have established after major fire. Overall, the studies suggest that the principal vegetation change at the sites took place after the start of the Industrial Revolution, and that the current landscape appearance not only has no long history, but that valued aspects, such as extensive heather moorland, feature only recently in the cultural landscape. These findings pose challenging questions for conservation management. We offer a non-specialist guide to the palaeoecological techniques that considers level of skill, cost, and comparability with ecological aspects of conservation and monitoring interest. We suggest palaeoecological data can provide valuable information and insights to aid practical conservation. While mires are particularly suitable, palaeoecological techniques could be applied in many other degraded landscapes internationally.

Using harvesting data to examine temporal and regional variation in red grouse abundance in the British uplands

Large areas of the British uplands consist of heather moorland, a habitat of global conservation importance that supports communities of threatened animal and plant species. Red grouse Lagopus lagopus scotica are dependent on heather and benefit from management of habitat, predators and parasites by gamekeepers employed to create a surplus of grouse for sport shooting. We compared numbers of red grouse shot across nine British regions over four discrete time periods (1890– 1920, 1920–1950, 1950–1980, 1980–2010) using annual records of shooting bags from 272 estates. We examined whether trends in numbers of grouse shot may be explained by changes in keeper density, heather moor extent or replacement of moorland by afforestation. Grouse bags were consistently higher in regions of northern England than in Scotland and Wales, and declined in all nine regions except southern Pennines from 1920 to 1950. Bags in northern England increased significantly from 1950, coinciding with increases in keeper density. In north‐east Scotland and Wales, numbers of grouse shot declined over the same period, coinciding with declines in keeper density and increased afforestation of moors. Regional variation in red grouse bag counts over time may be explained by changes in land use and management intensity affecting extent of suitable habitat and predator prevalence.

Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K

Two lowland catchments in the U.K. were sampled throughout 2010–11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350–400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350–400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function.

Impact of Management on Avian Communities in the Scottish Highlands

The protection of biodiversity is a key national and international policy objective. While protected areas provide one approach, a major challenge lies in understanding how the conservation of biodiversity can be achieved in the context of multiple land management objectives in the wider countryside. Here we analyse metrics of bird diversity in the Scottish uplands in relation to land management types and explore how bird species composition varies in relation to land managed for grazing, hunting and conservation. Birds were surveyed on the heather moorland areas of 26 different landholdings in Scotland. The results indicate that, in relation to dominant management type, the composition of bird species varies but measures of diversity and species richness do not. Intensive management for grouse shooting affects the occurrence, absolute and relative abundance of bird species. While less intensive forms of land management appear to only affect the relative abundance of species, though extensive sheep grazing appears to have little effect on avian community composition. Therefore enhanced biodiversity at the landscape level is likely to be achieved by maintaining heterogeneity in land management among land management units. This result should be taken into account when developing policies that consider how to achieve enhanced biodiversity outside protected areas, in the context of other legitimate land-uses.

Assessing prey provisioned to Common Buzzard Buteo buteo chicks: a comparison of methods

ABSTRACTCapsule: Methods of assessing raptor diet carry significant inherent biases which can vary over time.Aims: To compare methods of assessing Common Buzzard Buteo buteo diet composition and assess how any differences vary between years.Methods: Diet was assessed at 32 Common Buzzard nests on an area of upland heather moorland in Britain, managed for Red Grouse Lagopus lagopus scotica, over three years. Data obtained from nest cameras were compared with data from prey remains and regurgitated pellets.Results: Diet composition differed between methods in all years. Methodological differences varied between years in relation to an almost twelve-fold change in Field Vole abundance, a key prey of Common Buzzards, while abundances of alternative prey changed little. Small mammals were underestimated by prey remains in all three years, while herpetofauna were underestimated by prey remains and pellets in two years. Large birds were overestimated by prey remains, significantly so in one year. Pellets overestimated invertebrates in all years. By combining prey remains and pellets, significant yearly variations in biases were eliminated, although the combined measure overestimated large birds and invertebrates.Conclusion: Our results suggest that future studies should consider not only how chosen methods may affect results, but also how effects can differ between years.

THE LINKS BETWEEN LAND USE AND WATER QUALITY FOR FRESHWATER PEARL MUSSEL, MARGARITIFERA MARGARITIFERA, IN THE RIVER SOUTH ESK, SCOTLAND

The freshwater pearl mussel, Margaritifera margaritifera, is an endangered species and its population has decreased rapidly over the last century. Scotland is the home to half of the known populations of M. margaritifera. Land use is a significant factor affecting water quality as well as the distribution of freshwater pearl mussels. Thirty eight sites in River South Esk were selected to investigate the impacts of land use on water conductivity, pH and the concentration of nitrate and phosphorus on the distribution of mussels. M. margaritifera was more abundant in habitats in woodland with low and stable water nutrient level. Water chemical analysis indicates that pollutant concentration is related to the vegetation of river catchments. River water passing woodland has a relatively better quality and overhanging boughs of trees create shadows which attract mussels. Livestock pasture catchments seem to have less significant chemical effects, but animal activities may disturb the habitat of mussels and increase water turbidity. Water pollution in irrigated crop land is relatively higher. Heather moorland is of less concern because of its inappropriate channel type for mussels. Waters in the vicinity of housing, roads and bridges seem to be avoided by mussels. Margaritifera margaritifera did not show any preference on the type of shadows. Living mussels have been discovered at the sites which have shadows created by overhanging branches or high riverbanks.