Climate changes have profound effects on the distribution of numerous plant and animal species 1-3 . However, whether and how different taxonomic groups are able to track climate changes at large spatial scales is still unclear. Here, we measure and compare the climatic debt accumulated by bird and butterfly communities at a European scale over two decades (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008). We quantified the yearly change in community composition in response to climate change for 9,490 bird and 2,130 butterfly communities distributed across Europe 4 . We show that changes in community composition are rapid but different between birds and butterflies and equivalent to a 37 and 114 km northward shift in bird and butterfly communities, respectively. We further found that, during the same period, the northward shift in temperature in Europe was even faster, so that the climatic debts of birds and butterflies correspond to a 212 and 135 km lag behind climate. Our results indicate both that birds and butterflies do not keep up with temperature increase and the accumulation of different climatic debts for these groups at national and continental scales.Species are not equally at risk when facing climate change. Several species-specific attributes have been identified as increasing species' vulnerability to climate change, including diets, migratory strategy, main habitat types and ecological specialization [5][6][7] . Moreover, although phenotypic plasticity may enable some species to respond rapidly and effectively to climate change 8,9 , others may suffer from the induced spatial mismatch and temporal mistiming with their resources 10,11 . For instance, species such as great tits and flycatchers have been shown to become desynchronized with their main food supply during the nesting season 12 .However, beyond individual species' fates, climate change should also affect species interactions and the structure of species assemblages within and across different taxonomic groups over large spatial scales [13][14][15] . For instance, ectotherms should be more directly affected by climate warming and taxonomic groups with short generation time should favour faster evolutionary responses to selective pressures induced by climate changes 13 . Yet, whether different taxonomic groups are tracking climate change at the same rate over large areas is still unclear, and methods to routinely assess the mismatch between temperature increases and biodiversity responses at different spatial scales are still missing 16 .Here, we used extensive monitoring data of birds and butterflies distributed across Europe to assess whether, regardless of their species-specific characteristics, organisms belonging to a given group are responding more quickly or more slowly than organisms belonging to another group over large areas. We characterized bird and butterfly communities in 9,490 and 2,130 sample sites respectively by their community temperature index (CTI) for ea...

and {Hillcrest, Llanwrtyd Wells, Powys LD5 4TL, UK Summary 1. Over the past three decades changes in agricultural management have resulted in increased crop and grass production. This intensi®cation has been accompanied by population declines among farmland bird species and a decline in farmland biodiversity. We have analysed trends in agricultural management in order to quantify the degree of intensi®cation, and have considered how they match change in the farmland bird community. 2. Changes in agriculture through time (1962±95) were examined quantitatively for 31 variables representing crop areas, livestock numbers, fertilizer application, grass production and pesticide use. The majority were highly intercorrelated because factors facilitating intensi®cation simultaneously aected many management activities. 3. Change in agriculture was measured using detrended correspondence analysis (DCA). The period 1970±88 saw most intensi®cation, characterized by increases in the area of oilseed rape, autumn-sown cereals, and the use of pesticides and inorganic fertilizers. Spring-sown cereals, bare fallow and root crops declined. 4. Indices of relative population change between 1962 and 1996 were determined for 29 bird species using data from Common Birds Census (CBC) plots on farmland in England and Wales. Principal components analysis (PCA) described a gradient from species that had declined most to those that had increased. 5. The ordinations of agricultural change and bird population change were broadly matching but with a time lag in the response of birds. The most accurately measured agricultural variables for the period 1974±91 matched the changes in farmland birds more closely. 6. We conclude that large shifts in agricultural management are a plausible explanation for the declines in farmland bird populations. We propose a threshold model relating to critical amounts of high-quality habitat or food resources that may be relevant in explaining the lag in response of birds, and propose it should be taken into account in predicting the eects of future agri-environment schemes. Identifying individual factors responsible for bird declines is not possible without detailed experimental work because many components of intensi®cation are interdependent. Birds may be responding to a suite of interacting factors rather individual aspects of farm management. Holistic conservation strategy that encourages general extensi®cation of farming practices will be most likely to bene®t farmland bird communities.

w ww ww w. .f fr ro on nt ti ie er rs si in ne ec co ol lo og gy y. .o or rg g © © The Ecological Society of America T he popularity of bird feeding has increased rapidly in the past few decades. Up to 43% of households in the US regularly feed birds (Martinson and Flashpoler 2003), while in the UK, this figure is close to 75% (Cowie and Hinsely 1988). Food availability is clearly one of the main factors limiting bird populations, and supplementary feeding reduces the risk of starvation and may enhance reproductive performance (Newton 1998). Despite the impressive scale of bird feeding, understanding of the ecological effects of these massive subsidies is minimal. While bird feeding can bring positive benefits, such as increased overwinter survival and enhanced breeding success, there are also a number of potential negative impacts. For example, aggregations of birds around feeders may attract predators or enhance the spread of diseases. Feeders may also act as ecological traps, by providing inaccurate cues regarding habitat quality based on potential food resources.Experimental studies investigating the potential impacts of supplementary feeding have dealt with a range of species, from small passerines (Figure 1) to birds of prey. Directed feeding experiments do not reflect the large-scale, diffuse nature of backyard feeding, but may provide some indication of the wider impacts. The form of supplementary feeding varies markedly among studies, replicates are few, and treatments often run consecutively, sometimes as single-site, before-and-after comparisons. As a result, meta-analysis of this disparate body of research is challenging. To focus advice and future research, we have drawn together and reviewed the many and varied responses of bird populations to supplementary feeding (Table 1). We begin with the effects on avian demography, starting with egg laying, and then progress through the avian life cycle to effects on adult survival. Finally, we consider the implications for adult behavior, species interactions, and indirect, community-level effects. Egg layingThe acute need for energy during egg development and laying means that supplementary feeding is likely to affect REVIEWS REVIEWS REVIEWS I In n a a n nu ut ts sh he el ll l: :• Feeding birds is an enormously popular activity that can affect virtually every aspect of bird ecology, from daily survival to large-scale migration • Supplementary feeding has the potential to effect long-term changes in the population dynamics and distribution of some bird species • Although feeding birds generates mostly positive effects, some negative impacts, such as increased predation pressure and disease transmission, have also been observed • Research is required on the wider impacts of feeding and on the interactions between food supply and factors such as climate and predation GN Robb et al.Avian responses to supplementary feeding avian fecundity and resource allocation during reproduction. During the breeding season, time is constrained, and even small shifts toward...

There is an urgent need to thoroughly review and comprehend the effects of urbanization on wildlife in order to understand both the ecological implications of increasing urbanization and how to mitigate its threat to biodiversity globally. We examined patterns in comparative productivity of urban and non-urban passerine birds, using published estimates from paired comparisons, and by reviewing and developing explanations in terms of resources, competitors, predators and other specifically urban environmental factors. The most consistent patterns were for earlier lay dates, lower clutch size, lower nestling weight and lower productivity per nesting attempt in urban landscapes; these were supported by a formal meta-analysis. Nest failure rates did not show consistent patterns across the species considered. We suggest that food availability is a key driver of differences in passerine demography between landscapes. In urban habitats, human-provided food may improve adult condition over winter, leading to earlier lay dates and, in some species, to higher survival and higher breeding densities, but paucity of natural food may lead to lower productivity per nesting attempt. We demonstrate that additional comparative research is needed on a wider range of species, on the effects of natural and human-provided food availability, and on the differences in survival and dispersal between urban and non-urban populations. Importantly, better-targeted research and monitoring is needed in areas that are at greatest threat from urbanization, especially in the developing world.

Urban development is increasing across the globe. This poses a major threat to biodiversity, which is often relatively poor in towns and cities. Despite much interest in identifying species' traits that can predict their responses to environmental degradation this approach has seldom been used to assess which species are particularly vulnerable to urban development. Here we explore this issue, exploiting one of the best available datasets on species' responses to towns and cities in a highly urbanized region, comprising avian densities across approximately 3000 British urban and rural 1 km  1 km grid cells. We find that the manner in which species' responses to urbanization is measured has a marked influence on the nature of associations between these responses and species' ecological and life history traits. We advocate that future studies should use continuous indices of responses that take relative urban and rural densities into account, rather than using urban densities in isolation, or a binary response recording the presence/ absence of a species in towns and cities. Contrary to previous studies we find that urban development does not select against avian long-distance migrants and insectivores, or species with limited annual fecundity and dispersal capacity. There was no evidence that behavioural flexibility, as measured by relative brain size, influenced species' responses to urban environments. In Britain, generalist species, as measured by niche position rather than breadth, are favoured by urban development as are, albeit to a lesser extent, those that feed on plant material and nest above the ground. Our results suggest that avian biodiversity in towns and cities in urbanizing regions will be promoted by providing additional resources that are currently scarce in urban areas, and developing suitable environments for ground-nesting species.

Summary1. Evidence-based policy requires researchers to provide the answers to ecological questions that are of interest to policy makers. To find out what those questions are in the UK, representatives from 28 organizations involved in policy, together with scientists from 10 academic institutions, were asked to generate a list of questions from their organizations. 2. During a 2-day workshop the initial list of 1003 questions generated from consulting at least 654 policy makers and academics was used as a basis for generating a short list of 100 questions of significant policy relevance. Short-listing was decided on the basis of the preferences of the representatives from the policy-led organizations. 3. The areas covered included most major issues of environmental concern in the UK, including agriculture, marine fisheries, climate change, ecosystem function and land management. 4. The most striking outcome was the preference for general questions rather than narrow ones. The reason is that policy is driven by broad issues rather than specific ones. In contrast, scientists are frequently best equipped to answer specific questions. This means that it may be necessary to extract the underpinning specific question before researchers can proceed. Synthesis and applications.Greater communication between policy makers and scientists is required in order to ensure that applied ecologists are dealing with issues in a way that can feed into policy. It is particularly important that applied ecologists emphasize the generic value of their work wherever possible.

Aims  Biogeographical evidence suggests a strong link between climate and patterns of species diversity, and climate change is known to cause range shifts. However, there is little understanding of how shifts affect community composition and we lack empirical evidence of recent impacts of climate change on the diversity of vertebrates. Using a long‐term comprehensive dataset on bird abundance, we explore recent patterns of change in different components of species diversity and avian communities, and postulate a process to explain the observed changes in diversity and specialization. Location  Britain. Methods  We used Breeding Bird Survey data for Britain from 1994 to 2006 to calculate site‐specific diversity and community specialization indices. We modelled these indices using generalized additive models to examine the relationship between local climate and spatial and temporal trends in community metrics and the relationship between changes in diversity and specialization. Results  Local temperature was positively associated with alpha diversity, which increased over the study period, supporting empirical and theoretical predictions of the effect of climate warming. Diversity increased in all habitats, but the rate of increase was greatest in upland areas. However, temperature was negatively associated with community specialization indices, which declined over the same period. Our modelling revealed a nonlinear relationship between community specialization and species diversity. Main conclusions  Our models of diversity and specialization provide stark empirical evidence for a link between warming climate and community homogenization. Over a 13‐year period of warming temperatures, diversity indices increased while average community specialization decreased. We suggest that the observed diversity increases were most likely driven by range expansion of generalist species and that future warming is likely to increase homogenization of community structure. When assessed in combination, diversity and specialization measures provide a powerful index for monitoring the impacts of climate change.

Habitat and biodiversity differences between matched pairs of organic and non-organic farms containing cereal crops in lowland England were assessed by a large-scale study of plants, invertebrates, birds and bats. Habitat extent, composition and management on organic farms was likely to favour higher levels of biodiversity and indeed organic farms tended to support higher numbers of species and overall abundance across most taxa. However, the magnitude of the response varied; plants showed larger and more consistent responses than other taxa. Variation in response across taxa may be partly a consequence of the small size and isolated context of many organic farms. Extension of organic farming could contribute to the restoration of biodiversity in agricultural landscapes.