Search

SummaryConservation measures providing food-rich habitats through agri-environment schemes (AES) have the potential to affect the demography and local abundance of species limited by food availability. The European Turtle Dove Streptopelia turtur is one of Europe’s fastest declining birds, with breeding season dietary changes coincident with a reduction in reproductive output suggesting food limitation during breeding. In this study we provided seed-rich habitats at six intervention sites over a 4-year period and tested for impacts of the intervention on breeding success, ranging behaviour and the local abundance of territorial turtle doves. Nesting success and chick biometrics were unrelated to the local availability of seed-rich habitat or to the proximity of intervention plots. Nestling weight was higher close to human habitation consistent with an influence of anthropogenic supplementary food provision. Small home ranges were associated with a high proportion of non-farmed habitats, while large home ranges were more likely to contain seed-rich habitat suggesting that breeding doves were willing to travel further to utilize such habitat where available. Extensively managed grassland and intervention plot fields were selected by foraging turtle doves. A slower temporal decline in the abundance of breeding males on intervention sites probably reflects enhanced habitat suitability during territory settlement. Refining techniques to deliver sources of sown, natural, and supplementary seed that are plentiful, accessible, and parasite-free is likely to be crucial for the conservation of turtle doves.

Agri‐environment schemes (AES) are the main policy mechanism available for reversing the widespread declines of European farmland biodiversity. We assessed the impact of AES land management on the abundance of bird species whose populations have declined as a consequence of agricultural intensification. The AES involved the deployment of a whole‐farm package of wildlife‐friendly land management options covering an average of 7% of the farmed area. The study was conducted across three English regions and focused on species of conservation concern and on a wider suite of farmland birds comprising the UK Government's Farmland Bird Indicator (FBI). Changes in avian abundance on AES farms were compared with those measured across the wider farmed landscape as part of a national bird monitoring scheme. Twelve out of 17 priority species, and the FBI, showed more positive changes in abundance on AES farms in at least one region. Eight species exhibited sustained responses to AES management in at least one region, and eight species exhibited a temporary enhancement in abundance in at least one region. Temporary responses to AES management followed a large scale failure of key AES options to establish during successive wet and cold summers, and involved species known to depend on the habitats provided by these options. In order to offset ongoing declines of FBI species in the wider farmed countryside of 2.3–4.1% per annum, we estimate 26–33% of FBI populations would need to be subject to AES‐type management. This study demonstrates the potential for AES land management to substantially enhance the abundance of priority farmland birds and highlights the need for option packages that are resilient to the impacts of variable weather conditions.

SummaryPost-fledging survival plays a vital role in the dynamics of bird populations and yet is the least-studied avian life-stage. Habitat requirements post-fledging may have important implications for behaviour and survival, especially for declining populations in landscapes that have undergone wide-scale anthropogenic modification, resulting in an altered distribution and composition of habitats. The European Turtle Dove is a widespread but rapidly declining species both within the UK and across Europe. Reduced seed food availability is thought to influence breeding success of this species, but it is not known whether post-fledging survival may also be influenced by seed availability. Here, we use leg-ring radio-tag attachments to monitor post-fledging survival and movements in 15 Turtle Dove nestlings from eight nests monitored during 2014 as part of a wider autecological study. Fledglings remained in close proximity to their nest for three weeks post-tagging, spending more than half their time in the immediate vicinity (within ∼20 m) of the nest. 95% of foraging trips during this period were within 329 m of the nest and fledglings selected seed-rich habitat (semi-natural grassland, low-intensity grazing, fallow and quarries). Fledglings that were heavier and in better body condition at seven days old were more likely to survive for 30 days post-fledging, and the proportion of available seed-rich habitat was a strong predictor of nestling weight and condition at seven days old. Whilst our sample size is modest, this study highlights the crucial role of food availability in juvenile survival, both while adults are feeding nestlings, and to recently fledged young, and the potential for agri-environment schemes providing foraging and nesting habitats in close proximity to provide important benefits.

Agri-environment schemes (AES) are the main policy mechanism available to reverse the widespread losses of farmland biodiversity across Europe. Previous examples of AES enhancing the abundance of farmland birds have been restricted to targeted species recovery programmes, often with bespoke habitat management and high levels of advisory support for landowners. Here, we tested whether standard higher-tier AES agreements targeted at multiple species and with lower levels of advisory support than targeted species recovery programmes can enhance the breeding densities of farmland birds. Surveys of breeding birds were undertaken during 2008 and 2011 on 65 farms under higher level stewardship (HLS) and 21 farms lacking AES interventions, in three regions of England. After allowing for any impacts of predator control, changes in density were more positive on HLS farms in at least one region for six priority species. Five of the six species had mixed diets and were predominantly associated with field edges; the other (lapwing) probably responded to the provision of field-centre fallow plots. Changes in bird numbers were not consistently related to the extent of AES habitat provision. This is the first study to demonstrate that standard AES management without substantial ongoing advisory support can increase or maintain the densities of widespread declining species.

Agri-environment schemes (AES) are increasingly being employed to mitigate biodiversity loss in agricultural environments. The European Turtle Dove Streptopelia turtur is an obligate granivorous bird in rapid decline within both the UK (−96% since 1970) and across continental Europe (−77% since 1980), despite widespread uptake of AES. Here, we assess the efficacy of a potentially new, sown agri-environment option designed to provide abundant, accessible seed for S. turtur during the breeding season. During summer 2011 we compared vegetation structure and seed provision on trial plots to control habitat types (existing agri-environment options thought to potentially provide S. turtur foraging habitat) to assess whether trial plots performed better for foraging S. turtur than control habitats. In September 2011 all trial plots were topped (cut) and half of a subset of trial plots were then scarified (60% of soil surface disturbed). Vegetation structure on topped, and topped and scarified trial plots was measured during summer 2012 to determine which management regime was most effective in maintaining suitable sward structure and seed provision into the second year. No control habitat type produced as much seed important in S. turtur diet as trial plots at any point during year one. Trial plots provided accessible vegetation structure early in the season with no difference in vegetation metrics between trial plots and previously published data on S. turtur foraging locations. However, to allow later access, management is required during mid-June to open up the sward through localized topping or scarification. Vegetation structure during year two was generally too dense to attract foraging S. turtur. However, scarifying trial plots during the September following sowing encouraged self-seeding of Fumaria officinalis (a plant species historically forming a significant proportion of S. turtur diet during the breeding season) into the second year, with this species present in 16% of scarified trial plots compared to only 4% of topped trial plots during year two. Thus, autumn scarification, possibly followed by topping or scarification of part of the trial plots in June, is necessary for trial plots to provide more seed and access for S. turtur than existing agri-environment options during year two. We recommend modifications to our original seed mix in order to reduce vegetation density and improve vegetation structure. The study provides an example of the need to strike the right balance between food abundance and accessibility, through vegetation structure, when designing agri-environment scheme management options that provide food for birds.

Conserving farmland birds is a key objective for agri-environment schemes (AES) across Europe, with a number of management options aimed at providing invertebrate food and nesting habitats. We analysed territory settlement by two widespread but declining farmland buntings with contrasting nesting requirements: the Yellowhammer Emberiza citrinella, a boundary-nesting species, and the Corn Bunting Emberiza calandra, a ground-nesting species. The study was conducted on farms participating in the English Higher Level Stewardship scheme to test whether territory settlement is influenced by the provision of key arable AES options. Both species settled preferentially in localities containing sown arable field margins, while Corn Bunting also settled in localities containing nectar flower mixtures. These preferences are likely to reflect foraging rather than nesting habitat requirements. Yellowhammer selected territories containing hedgerows under AES management, which are nesting rather than foraging habitat but may also provide food. Uptake by land owners of several AES options likely to provide limiting resources for farmland birds was very low, and because uptake at the landscape scale is also low, wider-scale population level benefits are likely to be constrained. However, this is one of few studies demonstrating selection of widely applied arable AES options by breeding farmland birds.

Capsule Turtle Doves continue to show a strong population decline; territories were more likely to be retained in areas with more nesting habitat, and more suitable foraging habitat. Aim To determine which features of farmland in England are important for retaining Turtle Dove territories Methods Fifty-eight grid squares with recent records of territorial Turtle Doves were resurveyed, and squares retaining Turtle Dove territories compared with those from which Turtle Doves had been lost. Results Turtle Dove territories were detected in 48% of squares resurveyed. When correcting for the 70% detection rate of the survey methodology, territories were present in 66% of squares surveyed suggesting a 34% decline over a 2-year period. Established scrub and hedgerows > 4 m tall positively influenced Turtle Dove presence and abundance, as did standing water. Bare ground and fallow had positive effects on Turtle Dove abundance whereas grazed land negatively impacted abundance. Conclusion The positive effects of area of established scrub and volume of large hedgerows are likely to represent a declining density of birds selecting the best quality nest sites. We suggest instead that foraging habitat may be limiting distribution.

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.

Capsule At two demonstration farms, Game & Wildlife Conservation Trust's Loddington Farm in Leicestershire and Royal Society for the Protection of Birds's Hope Farm in Cambridgeshire, targeted management led to much faster increases in avian abundance than in the surrounding regions. Aims To compare changes in avian abundance at Loddington Farm since 1992 and Hope Farm since 2000, and relate these to regional trends in bird abundance and to the habitat and predator management conducted at the two sites. Methods Loddington Farm is a mixed arable 292-ha farm in a partially wooded landscape in Leicestershire. It was managed as a shoot from 1993 to 2002, combining habitat management with predator control (stopped in 2002) and winter grain provision (ceased in 2006). Hope Farm comprises a 181-ha mainly arable farm in an open landscape in Cambridgeshire, where habitat management for farmland birds has taken place since 2002. At both sites, breeding bird abundance has been monitored annually. Information on farm management was translated into three variables measuring annual provision of nesting cover, summer food and winter food. The number of Carrion Crow and Magpie territories was used as an index of predator abundance. Results Avian abundance increased at both farms much faster than within their respective regions. Recovery of priority species was positively correlated with the provision of summer foraging habitats and negatively correlated with the provision of supplementary grain during winter. The latter finding was counterintuitive and may reflect an increase in hedgerow provision that coincided with the cessation of grain provision at both farms. The increase in bird abundance was not sustained at Loddington Farm in the absence of predator control, although it was at Hope Farm where predator densities were markedly lower. Conclusion The data from Hope Farm suggest that where predator densities are relatively low (2 locally, 2 in spring regionally), recovery of farmland birds can be achieved through habitat management alone. Where predator densities are high (>5 corvid pairs/km2 and >1.1 foxes/km2), as at Loddington Farm, species recovery, particularly of open-cup nesting species, may require predator control as well as habitat management. Further study is needed to confirm this tentative conclusion from only two sites.

Agricultural intensification is believed to have driven declines of farmland bird populations and the invertebrates and weeds on which they feed. We investigated whether habitat and weather, as surrogates for food availability, influenced nestling growth rates and condition of four farmland passerines (Skylark Alauda arvensis, Chaffinch Fringilla coelebs, Linnet Carduelis cannabina and Yellowhammer Emberiza citrinella). We also tested whether nestling growth rates or condition influenced whether a brood subsequently fledged, starved or was depredated. Linnet nestlings are fed almost exclusively on seeds, and were unaffected by weather. Nestlings of the other species are fed mainly invertebrates and were affected negatively by rain but positively by increasing minimum temperatures and daily hours of sunshine. Condition and growth rates of Linnet nestlings were lower in nests further from oilseed-rape fields, rape seeds being important in the diet of this species. Nestlings of the other three species were unaffected by availability of habitats selected by parents foraging for nestling food. Brood fate was not influenced by growth rates or condition for any species. Most models explained little variation in the response variable. Possible reasons, including the possibility that parents trade off their own survival prospects to ensure reproductive success, are discussed.

Some agri-environment schemes promote the creation and management of a variety of non-crop habitats on farmland in the UK, yet there has been relatively little monitoring to assess how species, particularly birds, use these habitats. The present study deals with a declining UK farmland bird species, yellowhammer Emberiza citrinella , and considers to what extent grass margins of arable fields are used as a foraging habitat when feeding nestlings. Studies were carried out in lowland mixed farmland in southern England. Grass margins and other non-crop field boundary habitats, such as hedgerows and ditches, were selected relative to cropped areas by yellowhammers. No significant difference was found between use of cut and uncut grass margins. Studies have shown that grass margins support high densities of invertebrates and their provision at the edge of arable fields would benefit yellowhammers during the breeding season both as habitat for prey and as nesting habitat. During the breeding season from May to August, management should create cut and uncut grass margins in close proximity to each other. This could be achieved by cutting only the outer edge of the grass margin, maintaining cover next to the hedgerow. Cut areas would provide easier access to food resources for birds and prevent weed encroachment to the crop, whilst adjacent uncut areas would maintain invertebrate sources and provide nesting cover for yellowhammers.

Fine-scale habitat use by yellowhammers (Emberiza citrinella) searching for food to provision nestlings was compared in three agriculturally contrasting regions of lowland England. Log-linear modelling was used to test for significant overall variation in habitat use and significant differences in relative use between pairs of habitats. Yellowhammers provisioned nestlings non-randomly with respect to habitat availability. Habitat selection was found to be generally consistent across the three regions; field boundary structures and barley crops were the most selected foraging habitats, while intensively-managed grass fields were avoided relative to virtually all other habitats. The observed patterns of habitat selection are likely to result from an interaction of food abundance and varying accessibility to food, mediated by sward structure. The geographical generality of the results allows reasons to be suggested for the recent rapid population decline of the species and general conservation recommendations to be made with respect to lowland farmland.

Almost a third of the bird species designated as Species of European Conservation Concern exploit agricultural grasslands, yet few studies have focused on their use as foraging habitats for birds. This study investigated the influence of variation in sward structure, grassland management and landscape variables on the use of 77 grass fields by 14 field-feeding bird species wintering on lowland mixed farmland in southern England. Multiple logistic regression was used to model the proportion of bird-count visits in which each species was encountered as a function of the recorded habitat variables for each field. Variation in sward height and density were associated with frequency of occurrence for 12 bird species and larger areas of bare earth and occurrence of winter grazing by stock animals were correlated with greater frequency of occurrence by 11 bird species. Two rapidly declining species, skylark (Alauda arvensis) and yellowhammer (Emberiza citrinella), were recorded more frequently on fields with higher numbers of seeding grasses. We suggest that mosaics of fields managed as short-term leys and permanent pastures with low-intensity cattle grazing over the autumn and winter would provide the combination of heterogeneous sward structure, areas of bare earth and presence of some seeding plants necessary to maximise the range of bird species able to use a given area of agriculturally improved grassland throughout the winter.

1. Yellowhammers began to decline on British lowland farmland in the late 1980s and losses are presently 10% per year. This study examined variation in the habitat selection and breeding success of yellowhammers, allowing an evaluation of whether Britain's yellowhammer decline might have been caused by recent changes in agriculture. 2. Yellowhammer territories were associated with hedgerows, vegetated ditches and wide uncultivated grassy margins around fields. Pasture and silage leys were avoided. Nests were built among herbaceous vegetation in ditches or in the shrubby vegetation of hedgerows. 3. Breeding started slightly earlier on organic farms than on intensively managed farms, but no measure of breeding success differed between farm types. Predation was the cause of most (64%) nest failures. A maximum of three breeding attempts (two successful) was observed per pair, with a mean clutch size of 3·3, a Mayfield nest success rate of 0·46, and 2·6 nestlings fledged per successful brood. These data, together with published estimates of adult yellowhammer survival and of post-fledging survival among other passerines, suggest that breeding productivity is too low to maintain a stable population. 4. The removal of hedgerows or abandonment of hedge management, filling or clearing of ditches, intensification of grassland management and cropping or grazing right up to the field edge, are all likely to have adversely affected yellowhammers on lowland farmland in southern England. Policy reforms that redirect subsidy support to environmentally beneficial management of field margin habitats and retention of winter-feeding sites such as stubbles should assist in restoring populations of breeding yellowhammers on lowland farmland. 5. Our data expand further the array of farmland bird species for which interactions between agricultural change and population change are increasingly understood.

Between 1992 and 1993 over 600 000 ha of arable farmland in the UK were set aside under a production control mechanism of the Common Agricultural Policy (CAP) of the European Union. One of the management options for this set-aside land was to leave it as an over-winter fallow with a naturally regenerated green cover. This study was designed to test whether such land was used by seed-eating bird species, populations of many of which have undergone recent severe declines. Five out of six declining species recorded in the study were found in significantly greater numbers on this habitat than would be expected if the birds were randomly distributed over the farmland landscape. The results of this study, covering a wide geographical area, reinforce previous findings of the importance of winter food sources, particularly over-winter stubble fields, to declining farmland seed-eaters. Proposed changes to the CAP under Agenda 2000 include the reduction of the obligatory set-aside rate to zero. These results sugges...