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Summary1. Agri-environment schemes (AES) are used extensively across Europe to address biodiversity declines in farmland. In England, Environmental Stewardship (ES) was introduced in 2005 to address the shortcomings of previous schemes, but as for schemes in other countries, assessments to date have revealed little evidence for national-scale biodiversity benefits. 2. Here, we assess the efficacy of ES in driving changes in national farmland bird populations over the period 2002-2010, using BTO ⁄ JNCC ⁄ RSPB Breeding Bird Survey data. We tested for associations between ES management options, grouped into categories reflecting intended biological effects (e.g. stubble), and species' population growth rates, wherever benefits of management might be expected to occur. 3. We found strong evidence for positive effects of management that provides winter food resources (i.e. ES stubble and wild bird seed [WBS] crops) on population growth rates across multiple granivorous species, at three landscape scales. The results for management aiming to provide breeding season benefits (i.e. grassland, field margin and boundary [hedge, ditch] management) showed mixed patterns of positive and negative associations. 4. The results for stubble and WBS provide the first evidence for landscape-scale responses of biodiversity to AES management. The negative relationships identified may also show the importance of management context driving unforeseen predation or competition effects. 5. Synthesis and Applications. This study demonstrates that agri-environment scheme management has the potential to have national-scale effects on avian population growth rates, although our results suggest that some components of the scheme have had little effect on bird populations. Therefore, whilst this study provides the first proof-of-concept for broad-and-shallow scheme impacts on biodiversity, our results underline the importance of targeting towards populationlimiting factors, here winter food resources. A combination of low uptake of key in-field options that provide winter seed and a failure to cover the late-winter period effectively explains the lack of national population responses. Such issues need to be addressed before schemes like Environmental Stewardship will achieve their goals. This study shows the value of feedback from monitoring for informing scheme design, through identifying problems and testing solutions.

Recent large declines in house sparrow Passer domesticus L. populations in many European towns and cities have generated much speculation as to possible environmental causes, although empirical insights have been lacking. We measured reproductive success in a declining house sparrow population along an urbanization gradient in Leicester, England, and used mixed models to identify correlates of nesting success. A stochastic simulation approach was developed to estimate annual reproductive success when the number of breeding attempts was unknown, and to assess the sensitivity of reproductive success to variation in different environmental factors. During 2 out of 3 years, reproductive output was lower than the predicted threshold required for population stability. Years of inadequate reproduction were characterized by lower chick survival and body mass at fledging (a predictor of post-fledging survival). Factors associated with reduced reproductive output included low ambient temperatures, extremes of rainfall, high levels of vegetable material in the diet (all affecting chick survival and body mass), low aphid densities (an important component of chick diet) and high concentrations of air pollution from traffic (affecting chick body mass). Reproductive failure linked to inadequate invertebrate availability provides a plausible demographic mechanism accounting for declines in urban-suburban house sparrow populations. Increased traffic volume and vegetation removal are candidate causal factors in these declines although the mechanism underlying the former is unclear. Increasing densities of key invertebrate prey away from major roads should be an objective of conservation management aimed at urban-suburban house sparrows. This study illustrates the utility of mixed models for the analysis of individual sibling survival and of stochastic simulation for modelling reproductive success in multi-brooded animals.

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Dietary changes linked to the availability of anthropogenic food resources can have complex implications for species and ecosystems, especially when species are in decline. Here, we use recently developed primers targeting the ITS2 region of plants to characterize diet from faecal samples of four UK columbids, with particular focus on the European turtle dove (Streptopelia turtur), a rapidly declining obligate granivore. We examine dietary overlap between species (potential competition), associations with body condition in turtle doves and spatiotemporal variation in diet. We identified 143 taxonomic units, of which we classified 55% to species, another 34% to genus and the remaining 11% to family. We found significant dietary overlap between all columbid species, with the highest between turtle doves and stock doves (Columba oenas), then between turtle doves and woodpigeons (Columba palumbus). The lowest overlap was between woodpigeons and collared doves (Streptopelia decaocto). We show considerable change in columbid diets compared to previous studies, probably reflecting opportunistic foraging behaviour by columbids within a highly anthropogenically modified landscape, although our data for nonturtle doves should be considered preliminary. Nestling turtle doves in better condition had a higher dietary proportion of taxonomic units from natural arable plant species and a lower proportion of taxonomic units from anthropogenic food resources such as garden bird seed mixes and brassicas. This suggests that breeding ground conservation strategies for turtle doves should include provision of anthropogenic seeds for adults early in the breeding season, coupled with habitat rich in accessible seeds from arable plants once chicks have hatched.

23SG19 2DL, UK. +44 (0)

Declines in habitat quality through the breeding season within a bird's home-range can limit overall productivity. In environments where multiple breeding opportunities arise during the course of a season, these effects can be buffered by a shift to different breeding sites or habitats. We studied the distribution and habitat associations of a crop-nesting farmland bird, the Yellow Wagtail Motacilla flava, across an arable-dominated farming region in eastern England using both field-scale territory mapping and large-scale transect surveys. Surveys were repeated at monthly intervals to measure changes in both distribution and habitat use during the course of the season. The distribution of breeding birds changed markedly at both regional and field-scales, coinciding with a shift in crop preference. Initially, most territorial birds were recorded in autumn-sown cereal fields, but this crop was subsequently abandoned in favour of potato crops, which were more patchily distributed. Other habitat features influencing Yellow Wagtail distribution included local crop diversity, hedgerow presence and soil type, with organic soils supporting higher abundance than alluvial clays or silts. The mid-season switch in habitat associations might allow individuals to maximize the number of breeding attempts made in a single year by using multiple habitats sequentially. The use of multiple habitats could influence population regulation by buffering the effects of local within-season declines in habitat suitability. Seasonal habitat switching may be more prevalent than is currently recognized in seasonal environments. © 2009 British Ornithologists' Union