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The establishment and maintenance of a system of protected areas is central to regional and global strategies for the conservation of biodiversity. The current global trend towards human population growth and widespread environmental degradation means that such areas are becoming increasingly isolated in fragmented habitat islands. In regions in which this process is well advanced a high proportion of species are thus predicted to have become restricted to protected areas. Here using uniquely detailed datasets for Britain, a region with close to the global level of percentage coverage by statutory protected areas, we determine the extent of restriction of Red List vascular plant species of conservation concern to these areas. On the basis of currently known distributions, overall our results strongly support the importance of a dual conservation strategy in Britain, in which protected areas are maintained with particular reference to those biodiversity features (such as many threatened plant species) that are highly dependent on them, and in which components of the wider landscape are also managed in such a way as to promote the abundance and distribution of such features with particular reference to those which are unlikely to persist in protected areas alone.

Common species have a greater effect on observed geo- graphical patterns of species richness than do rare ones. Here we present a theory of the relationship between individual species oc- currence patterns and patterns in species richness, which allows purely geometrical and statistical causes to be distinguished from biological ones. Relationships between species occupancy and the correlation of species occurrence with overall species richness are driven by the frequency distribution of species richness among sites. Moreover, generally positive relationships are promoted by the fact that species occupancy distributions are mostly right skewed. How- ever, biological processes can lead to deviations from the predicted pattern by changing the nestedness of a species' spatial distribution with regard to the distributions of other species in an assemblage. We have applied our theory to data for European birds at several spatial scales and have identified the species with significantly stron- ger or weaker correspondence with the overall richness pattern than that predicted by the null model. In sum, whereas the general macro- ecological pattern of a stronger influence of common species than of rare species on species richness is predicted by mathematical con- siderations, the theory can reveal biologically important deviations at the level of individual species.

Despite increasing interest in urban ecology most attention has focussed on describing changes in assemblage composition and structure along urbanisation gradients, whilst relatively little research has focussed on the mechanisms behind these changes. Ecological theory predicts that alterations in biotic interactions are particularly likely to arise, especially with regard to disease risk. Here, we report on differences in prevalence of avian malaria and tick infection and intensity in 11 paired urban and rural blackbird Turdus merula populations from across the western Palearctic. We find large and consistent reductions in tick prevalence and intensity in urban areas. There are also large reductions in the prevalence of avian malaria in many, but not all, urban areas. The proportion of first year birds in urban populations is significantly lower than that in rural ones, and across the more natural rural sites southerly populations contain fewer first years than northern ones. These patterns are expected to arise if survival rates are higher in urban areas, and are negatively correlated with latitude.

Biodiversity-rich, resource-poor countries need to allocate scarce resources to the competing goals of identifying and monitoring their biodiversity and educating their populace about it. Often only relatively wealthy individuals participate in biodiversity-related volunteering, while the poor are left on the margins. We present a case study that shows how monitoring and education can be combined. South African high school scholars from mostly disadvantaged communities participated in ant monitoring in transformed sites and received lessons using their own data. The project provides baseline data on an important insect group in a region where invertebrate monitoring is rare. Participation in a real study enhances the scholars’ interest in science and direct interaction with scientists allows them to enquire about careers they might not otherwise consider. Here we outline how the project works, what participants learnt, and demonstrate that the data provide insights into ant diversity and the effects of landscape transformation.

Few empirical studies examine how conservation organizations distribute the resources that they have available for habitat conservation, despite numerous theoretical studies that recommend how these resources should be directed. Here we examine the distribution of conservation investments made over 49 years by a major conservation nongovernmental organization (NGO), The Nature Conservancy (TNC). We measured the level of conservation effort across U.S. states by the area protected and the upfront cost of protection, accounting for easements and land acquisitions. While correlated, we show that two measures of conservation effort (area and amount invested) cannot be used as reliable proxies for one another. The distributions of both measures of conservation effort are explained by combinations of one biological (species richness) and three socioeconomic (land price, rate of development and action of other NGOs) factors, revealing a generally strategic pattern of investment by TNC. Finally, we identify examples of underinvestment in particular states by TNC.

1. The 20th century has witnessed substantial increases in the intensity of agricultural land management, much of which has been driven by policies to enhance food security and production. The knock-on effects in agriculturally dominated landscapes include habitat degradation and biodiversity loss. We examine long-term patterns of agricultural and habitat change at a regional scale, using the Peak District of northern England as a case study. As stakeholders are central to the implementation of successful land-use policy, we also assess their perceptions of historical changes. 2. In the period 1900 to 2000, there was a fivefold rise in sheep density, along with higher cattle density. We found a reduction in the number of farms, evidence of a shift in land ownership patterns, and increased agricultural specialization, including the virtual disappearance of upland arable production. 3. Despite previous studies showing a substantial loss in heather cover, we found that there had been no overall change in the proportion of land covered by dwarf shrub moor. Nonetheless, turnover rates were high, with only 55% of sampled sites maintaining dwarf shrub moor coverage between 1913 and 2000. 4. Stakeholders identified many of the changes revealed by the historical data, such as increased sheep numbers, fewer farms and greater specialization. However, other land-use changes were not properly described. For instance, although there had been no overall change in the proportion of dwarf shrub moor and the size of the rural labour force had not fallen, stakeholders reported a decline in both. Spatial heterogeneity of the changes, shifting baselines and problems with historical data sources might account for some of these discrepancies. 5. Synthesis and applications. A marked increase in sheep numbers, combined with general agricultural intensification, have been the dominant land-use processes in the Peak District during the 20th century. Stakeholders only correctly perceived some land-use changes. Policy and management objectives should therefore be based primarily on actual historical evidence. However, understanding stakeholder perceptions and how they differ from, or agree with, the available evidence will contribute to the successful uptake of land management policies and partly determine the costs of policy implementation.

Summary 1 Conservation and natural resource management challenges are as much social problems as biological ones. In recognition of this fact, ecologists and economists work increasingly closely together. We discuss one barrier to effective integration of the two disciplines: put simply, many ecologists and economists approach statistical regression differently. 2 Regression techniques provide the most commonly used approach for empirical analyses of land management decisions. Researchers from each discipline attribute differing importance to a range of possibly conflicting design criteria when formulating regression analyses. 3 Ecologists commonly attribute greater importance to spatial autocorrelation and parsimony than do economists when designing regressions. Economists often attribute greater importance than ecologists to concerns about endogeneity and conformance with a priori theoretical expectations. 4 Synthesis and applications. The differing importance attributed to different design characteristics may reflect a process of cultural drift within each discipline. Greater interdisciplinary collaboration can counteract this process by stimulating the flow of ideas and techniques across disciplinary boundaries.

Aim Urban environments are often characterized as supporting a few abundant, generalist species best adapted to living alongside humans, and as such, cities are seen as agents of biotic homogenization. However, there are surprisingly few descriptions of biological populations found in cities. Here, we provide the first complete citywide population estimates of birds for any UK city, and examine the conservation status of the assemblage in comparison with the country’s avifauna at large. Location Sheffield city, central UK Methods We surveyed birds in every 500 m × 500 m square across the 160 km 2 of the city. Using a Distance sampling protocol, we estimated bird population sizes for the city and compared these with the size of the human population. We also compared the conservation status of the city’s avian population with that of birds across the UK as a whole. Results Aggregation of population estimates for the 77 species observed during the surveys produced a total estimate of 602,995 (95% confidence interval (CI): 404,565‐942,573) breeding birds, equating to 1.18 birds per person. The size of the non-breeding population was similar at 578,603 (464,396‐728,574) individuals, or 1.13 birds per person. Surveys revealed only three non-native species, but relatively few species of national conservation concern. However, some species of conservation concern achieved very high population densities within the city, and the overall density of birds was more than six times that of the nation at large. Main conclusions If declines in some species are to be arrested or reversed, conservation effort will need to focus much more strongly on understanding and managing urban populations, because these might buffer some species against wholesale regional population depletion, particularly where intensive agriculture in the surrounding hinterland has led to declines in bird populations at large. Such a focus will require a significant increase in the priority and resources devoted to conservation activities in urban areas.

Capsule Daylength, rather than latitude, was found to be an important determinant of variation in clutch size. Aims To describe the nature of spatial and temporal variation in clutch size, and explore the ecological correlates of these patterns. Methods We tested the prediction that seasonal declines in clutch size will be greater at higher latitudes. The environmental variables focused on were the influence of daylength, plant productivity, seasonality (i.e. Ashmole's hypothesis) and physiological mechanisms that relate clutch size to ambient temperature. We used data from 1980 to 2003 on spatial variation in clutch size across Britain for single‐brooded species, in which clutch size can be taken as a measure of annual reproductive investment. We included all seven species, from five families, with sufficient data in the British Trust for Ornithology's Nest Record Scheme. Results There are strong seasonal declines in clutch size but little evidence for latitudinal gradients in clutch size or in latitudin...

Most people on the planet live in dense aggregations, and policy directives emphasize green areas within cities to ameliorate some of the problems of urban living. Benefits of urban green spaces range from physical and psychological health to social cohesion, ecosystem service provision and biodiversity conservation. Green space coverage differs enormously among cities, yet little is known about the correlates or geography of this variation. This is important because urbanization is accelerating and the consequences for green space are unclear. Here, we use standardized major axis regression to explore the relationships between urban green space coverage, city area and population size across 386 European cities. We show that green space coverage increases more rapidly than city area, yet declines only weakly as human population density increases. Thus, green space provision within a city is primarily related to city area rather than the number of inhabitants that it serves, or a simple space-filling effect. Thus, compact cities (small size and high density) show very lowper capitagreen space allocation. However, at high levels of urbanicity, the green space network is robust to further city compaction. As cities grow, interactions between people and nature depend increasingly on landscape quality outside formal green space networks, such as street plantings, or the size, composition and management of backyards and gardens.

Resilience is a general concept that aims to help understand how ecosystems respond to disturbances such as extinctions and invasions. Here, we propose a measure of one aspect of resilience, R X , which is one minus the expected change in functional diversity (X) caused by a species extinction or addition. We show how two components of biodiversity, species richness and functional diversity, and the structure of regional species pools affect this measure. Variation in species richness and in functional diversity have opposite effects on R X . Speciose assemblages generally have higher R X than depauperate ones, whereas functionally diverse assemblages have low R X relative to functionally depauperate ones. The effect of an extinction on R X reflects this tradeoff. In our analyses, extinctions usually cause only a small decrease in both functional diversity and R X . However, extinctions sometimes cause a large reduction in functional diversity and then tend to increase R X . Regional assemblages containing all rather unique species tend to result in speciose assemblages with relatively low R X and in low richness assemblages with relatively high R X . The opposite is true of regional assemblages containing functionally similar species. Information about the processes that structure regional assemblages will therefore increase understanding of ecosystem resilience. Generally, these results suggest that management for biodiversity may not always result in management for resilience.

An effective portfolio of protected areas should, all else being equal, give rise to positive relationships between the amount of protected land in a region and the numbers of species present. Tests of this prediction are, however, extremely scarce, and most do not control for the potentially confounding effects of environmental factors that influence broad geographic trends in biodiversity. Here, we document the form of the relationship between species richness and coverage by protected areas using the British avifauna as a case study. We contrast relationships that arise for breeding and wintering assemblages, considering both all species collectively and threatened species only. We use spatially explicit multiple regression analyses that take into account environmental factors previously shown to exert a marked influence on avian species richness in Britain (temperature and altitude). Avian species richness and the amount of protected land are consistently positively correlated with each other, and the slopes of these relationships do not differ between assemblages (breeding/wintering and all species/threatened species). Explanatory power is, however, very weak which may be indicative of the ability of conservation measures in the wider landscape to maintain avian species richness, reducing any distinctive influence of protected areas.

Summary 1. Geographic range size and how it changes through time is one of the fundamental ecological and evolutionary characteristics of a species, and a strong predictor of extinction risk. However, the measurement of range size remains a substantial challenge. Indeed, there is significant confusion in the literature as to how this should be done, particularly in the context of the distinction between the fundamentally different concepts of extent of occurrence (EOO) and area of occupancy (AOO), and the use of these quantities, including in assessments of the threat status of species. 2. Here we review the different approaches to determining the geographic distributions of species, the measurement of their range sizes, the relationships between the two, and other difficulties posed by range size measurement (especially those of range discontinuities when measuring EOO, and spatial scale when measuring AOO). 3. We argue that it is important to (i) distinguish the estimation of the distribution of a species from the measurement of its geographic range size; (ii) treat measures of EOO and AOO as serving different purposes, rather than regarding them as more or less accurate ways of measuring range size; and (iii) measure EOO including discontinuities in habitat or occupancy. 4. Synthesis and applications. With the availability and collation of extensive data sets on species occurrences, a rapidly increasing number of studies are investigating geographic range size, and particularly how various measures of range size predict macroecological patterns and inform assessments of the conservation status of species and areas. The distinction between EOO and AOO is becoming blurred in many contexts, but most particularly in that of threatened species assessments for Red Listing. Continued progress in these fields demands greater clarity in the meaning and derivation of measures of geographic range size. The two principal measures serve different purposes, and should not be regarded as alternatives that simply differ in accuracy.

Urban areas occupy a large and growing proportion of the earth. Such sites exhibit distinctive characteristics relative to adjacent rural habitats, and many species have colonised and now successfully exploit urban habitats. The change in selection pressures as a result of urbanisation has led to trait divergence in some urban populations relative to their rural counterparts, but studies have generally been local in scale and the generality of differentiation thus remains unknown. The European blackbird Turdus merula is one of the commonest urban bird species in the Western Palearctic, but populations vary substantially in the length of time they have been urbanised. Here we investigate patterns of morphological variation in European blackbirds occupying 11 paired urban and rural habitats across much of the urbanised range of this species and spanning 25 degrees of latitude. First, we assessed the extent to which urban and rural blackbirds are differentiated morphologically and the consistency of any differentiation across the range. Paired urban and rural Blackbird populations frequently exhibited significant morphological differences, but the magnitude and direction of differentiation was site dependent. We then investigated whether the nature of latitudinal gradients in body-size differed between urban and rural populations, as predicted by differences in the climatic regimes of urban and rural areas. Blackbird body-size exhibited strong latitudinal gradients, but their form did not differ significantly between urban and rural habitats. The latitudinal gradient in body size may be a consequence of Seebohm's rule, that more migratory populations occurring at high latitudes have longer wings. We conclude that while there can be substantial morphological variation between adjacent urban and rural bird populations, such differentiation may not apply across a species' range. Locality specific differentiation of urban and rural blackbirds may arise if the selection pressures acting on blackbird morphology vary in an inconsistent manner between urban and rural habitats. Alternatively, phenotypic divergence could arise in a stochastic manner depending on the morphological traits of colonists, through founder effects.

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.

Urbanization is increasing across the globe and there is growing interest in urban ecology and a recognition that developed areas may be important for conservation. We review the factors influencing urban avian assemblages, focusing on habitat type and anthropogenic resource provision, and analyse data from a common bird monitoring scheme to assess some of these issues. The review suggests that (1) local factors are more important than regional ones in determining the species richness of urban avian assemblages, raising the potential for the management of urban sites to deliver conservation; (2) habitat fragmentation frequently influences urban avian assemblages, with the effects of patch size being greater than those of isolation, and (3) urban bird assemblages appear to respond positively to increasing the structural complexity, species richness of woody vegetation and supplementary feeding, and negatively to human disturbance. Data from Britain's Breeding Bird Survey, combined with habitat data obtained from aerial photographs, were used to assess a number of these issues at the resolution of 1-km squares. Green-space constituted 45% of these squares, and domestic gardens contributed 50% of this green-space, though their contribution to large continuous patches of green-space was negligible. There was no significant positive correlation between the densities of individual species in urban areas and surrounding rural areas. Rural species richness declined with increasing latitude, but urban species richness was not correlated with latitude. This contrast contributes to slightly higher avian species richness in rural squares in Southern England than urban ones. Occupancy and abundance were strongly positively correlated in urban avian assemblages, and some indicator species of conservation concern occurred in few urban areas and at low densities. Such species will require conservation action to be precisely targeted within urban areas. Of the urban indicators of conservation concern, only the House Sparrow Passer domesticus and Common Starling Sturnus vulgaris were more abundant in urban than rural areas. Moreover, the densities of these two species were strongly and positively correlated, indicating that they may be limited by shared resources, such as nest-sites or supplementary food. There was little evidence that high densities of nest-predating corvids were associated with reduced densities of their prey species. Species richness and the densities of individual species frequently declined with an increasing number of buildings. Current trends for the densification of many British urban areas are thus likely to be detrimental for many bird species.

Many attempts to explain the species-abundance distribution (SAD) assume that it has a universal functional form which applies to most assemblages. However, if such a form does exist, then it has to be invariant under changes in the area of the study plot (the addition of neighboring areas or subdivision of the original area) and changes in taxonomic composition (the addition of sister taxa or subdivision to subtaxa). We developed a theory for such an area-and-taxon invariant SAD and derived a formula for such a distribution. Both the log-normal and our area-and-taxon invariant distribution fitted data well. However, the log-normal distributions of two adjoined sub-assemblages cannot be composed into a log-normal distribution for the resulting assemblage, and the SAD composed from two log-normal distributions fits the SAD for the assemblage poorly in comparison to the area-and-taxon invariant distribution. Observed abundance patterns therefore reveal area-and-taxon invariant properties absent in log-normal distributions, suggesting that multiplicative models generating log-normal-like SADs (including the power-fraction model) cannot be universally valid, as they necessarily apply only to particular scales and taxa.

Protected areas are a cornerstone of local, regional, and global strategies for the conservation of biodiversity. However, the ecological performance of these areas, both in terms of the representation and the maintenance of key biodiversity features, remains poorly understood. A large and rapidly expanding literature bears on these issues, but it is highly fragmented, principally comprises particular case studies, and employs a diverse array of approaches. Here we provide a synthetic review of this work, discriminating between issues of performance of inventory and condition at the scale of individual protected areas, portfolios, and networks of protected areas. We emphasize the insights that follow and the links between the different issues, as well as highlight the major problems that remain unresolved.

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species was increasingly used during the 1980s to assess the conservation status of species for policy and planning purposes. This use stimulated the development of a new set of quantitative criteria for listing species in the categories of threat: critically endangered, endangered, and vulnerable. These criteria, which were intended to be applicable to all species except microorganisms, were part of a broader system for classifying threatened species and were fully implemented by IUCN in 2000. The system and the criteria have been widely used by conservation practitioners and scientists and now underpin one indicator being used to assess the Convention on Biological Diversity 2010 biodiversity target. We describe the process and the technical background to the IUCN Red List system. The criteria refer to fundamental biological processes underlying population decline and extinction. But given major differences between species, the threatening processes affecting them, and the paucity of knowledge relating to most species, the IUCN system had to be both broad and flexible to be applicable to the majority of described species. The system was designed to measure the symptoms of extinction risk, and uses 5 independent criteria relating to aspects of population loss and decline of range size. A species is assigned to a threat category if it meets the quantitative threshold for at least one criterion. The criteria and the accompanying rules and guidelines used by IUCN are intended to increase the consistency, transparency, and validity of its categorization system, but it necessitates some compromises that affect the applicability of the system and the species lists that result. In particular, choices were made over the assessment of uncertainty, poorly known species, depleted species, population decline, restricted ranges, and rarity; all of these affect the way red lists should be viewed and used. Processes related to priority setting and the development of national red lists need to take account of some assumptions in the formulation of the criteria.La Lista Roja de Especies Amenazadas de la UICN (Union Internacional para la Conservacion de la Naturaleza) fue muy utilizada durante la decada de l980 para evaluar el estatus de conservacion de especies para fines politicos y de planificacion. Este uso estimulo el desarrollo de un conjunto nuevo de criterios cuantitativos para enlistar especies en las categorias de amenaza: en peligro critico, en peligro y vulnerable. Estos criterios, que se pretendia fueran aplicables a todas las especies excepto microorganismos, eran parte de un sistema general para clasificar especies amenazadas y fueron implementadas completamente por la UICN en 2000. El sistema y los criterios han sido ampliamente utilizados por practicantes y cientificos de la conservacion y actualmente apuntalan un indicador utilizado para evaluar el objetivo al 2010 de la Convencion de Diversidad Biologica. Describimos el proceso y el respaldo tecnico del sistema de la Lista Roja de la IUCN. Los criterios se refieren a los procesos biologicos fundamentales que subyacen en la declinacion y extincion de una poblacion. Pero, debido a diferencias mayores entre especies, los procesos de amenaza que los afectan y la escasez de conocimiento sobre la mayoria de las especies, el sistema de la UICN tenia que ser amplio y flexible para ser aplicable a la mayoria de las especies descritas. El sistema fue disenado para medir los sintomas del riesgo de extincion, y utiiza cinco criterios independientes que relacionan aspectos de la perdida poblacional y la declinacion del rango de distribucion. Una especie es asignada a una categoria de amenaza si cumple el umbral cuantitativo por lo menos para un criterio. Los criterios, las reglas acompanantes y las directrices utilizadas por la UICN tienen la intencion de incrementar la consistencia, transparencia y validez de su sistema de clasificacion, pero requiere algunos compromisos que afectan la aplicabilidad del sistema y las listas de especies que resultan. En particular, se hicieron selecciones por encima de la evaluacion de incertidumbre, especies poco conocidas, especies disminuidas, declinacion poblacional, rangos restringidos y rareza; todas estas afectan la forma en que las listas rojas deberian ser vistas y usadas. Los procesos relacionados con la definicion de prioridades y el desarrollo de las listas rojas nacionales necesitan considerar algunos de los supuestos en la formulacion de los criterios.

Species-area relationships (SARs) are fundamental to the study of key and high-profile issues in conservation biology and are particularly widely used in establishing the broad patterns of biodiversity that underpin approaches to determining priority areas for biological conservation. Classically, the SAR has been argued in general to conform to a power-law relationship, and this form has been widely assumed in most applications in the field of conservation biology. Here, using nonlinear regressions within an information theoretical model selection framework, we included uncertainty regarding both model selection and parameter estimation in SAR modeling and conducted a global-scale analysis of the form of SARs for vascular plants and major vertebrate groups across 792 terrestrial ecoregions representing almost 97% of Earth's inhabited land. The results revealed a high level of uncertainty in model selection across biomes and taxa, and that the power-law model is clearly the most appropriate in only a minority of cases. Incorporating this uncertainty into a hotspots analysis using multimodel SARs led to the identification of a dramatically different set of global richness hotspots than when the power-law SAR was assumed. Our findings suggest that the results of analyses that assume a power-law model may be at severe odds with real ecological patterns, raising significant concerns for conservation priority-setting schemes and biogeographical studies.

Summary 1. Population estimates are of fundamental importance for setting conservation priorities and for numerous aspects of conservation biology. 2. Distance sampling, which takes undetected individuals into account, is one of the most widely used methods for generating population estimates. We use this method to generate estimates of the national population size for all common and widespread non-marine breeding birds in the UK using Breeding Bird Survey data. 3. There is a strong positive relationship between our distance-sampled estimates and estimates generated using other methods. This implies that most methods get the broad picture right, even if one of them is less precise for individual species. 4. For some species, detectability may vary sufficiently between males and females to generate biases in population size estimates if these differences are not taken into account. We found a slight tendency for population estimates from distance sampling to be lower than existing estimates for species with marked sex biases in detectability. This may be a wider problem than is currently acknowledged in distance sampling. 5. Distance sampling provides a method for estimating total population size. Other bird population survey methods, such as intensive territory mapping, aim to count the number of breeding pairs, and thus exclude non-breeding individuals. Not surprisingly, we found that distance-sampled estimates tended to be higher for species with a large proportion of non-breeders. Both approaches are valid, but when calculating, reporting and using population estimates attention needs to be paid to which variable is of most interest. 6. The new estimates that we present are significantly larger than existing ones for species whose preferred habitat types were not previously well surveyed. This highlights the importance of sampling across all main habitat types. 7. Synthesis and applications. This study reviews alternative methods used for producing estimates of population size for common and widespread breeding birds in the UK. We assess a number of

There have been several attempts to build a unified framework for macroecological patterns. However, these have mostly been based either on questionable assumptions or have had to be parameterized to obtain realistic predictions. Here, we propose a new model explicitly considering patterns of aggregated species distributions on multiple spatial scales, the property which lies behind all spatial macroecological patterns, using the idea we term 'generalized fractals'. Species' spatial distributions were modelled by a random hierarchical process in which the original 'habitat' patches were randomly replaced by sets of smaller patches nested within them, and the statistical properties of modelled species assemblages were compared with macroecological patterns in observed bird data. Without parameterization based on observed patterns, this simple model predicts realistic patterns of species abundance, distribution and diversity, including fractal-like spatial distributions, the frequency distribution of species occupancies/abundances and the species-area relationship. Although observed macroecological patterns may differ in some quantitative properties, our concept of random hierarchical aggregation can be considered as an appropriate null model of fundamental macroecological patterns which can potentially be modified to accommodate ecologically important variables.

Aim To attack a widespread myth. Location World-wide. Methods Simple mathematical logical and empirical examples. Results As both species and area are finite and non-negative, the species–area relationship is limited at both ends. The log species–log area relationship is normally effectively linear on scales from about 1 ha to 107 km2. There are no asymptotes. At the intercontinental scale it may get steeper; at small scales it may in different cases get steeper or shallower or maintain its slope. Main conclusion The species–area relationship does not have an asymptote.

Aim: To determine how well variation in median body size of avian assemblages is predicted by (1) the environmental models usually employed in analyses of Bergmann's rule and (2) random sampling from the regional body size frequency distribution. If body size frequency distributions of local assemblages represent a random sample of a regional frequency distribution, then geographical variation in body sizes of assemblages might be a consequence of the determinants of spatial variation in species richness rather than direct influences on body size per se. Location: Southern Africa. Methods: Median body masses (as a measure of body size) of avian assemblages were calculated for quarter-degree grid cells across South Africa and Lesotho. The relationship between median body mass and four environmental variables (minimum and maximum monthly temperatures, precipitation and seasonality in the normalized difference vegetation index, as a measure of seasonality in productivity) was examined using general linear models first without taking spatial autocorrelation into account, and then accounting for it by fitting an exponential spatial covariance structure. Model fit was assessed using the Akaike information criterion and Akaike weights. At each species richness value, random assemblages were sampled by either drawing species randomly from the regional body mass frequency distribution, or drawing species from the regional body mass frequency distribution with a probability proportional to their geographical distribution in the area. The ability of randomizations to predict actual body masses was examined using two-tailed Fisher exact tests. Results: Seasonality in productivity was the only environmental variable that remained a significant predictor of body mass variation in spatially explicit models, though the positive relationship was weak. When species richness was included in the models it remained the only significant predictor of size variation. Randomizations predicted median body mass poorly at low species richness, but well at high richness. Main conclusions: Environmental models that have previously been proposed explain little of the variation in body mass across avian assemblages in South Africa. However, much of the variation in the median mass of assemblages could be predicted by randomly drawing species from the regional body mass frequency distribution, particularly using randomizations in which all species were drawn from the regional body mass frequency distribution with equal probability and at high species richness values. This outcome emphasizes the need to consider null expectations in investigations of the geographical variation in body size together with the probable environmental mechanisms underlying spatial variation in average size. Moreover, it suggests that in the South African avifauna, spatial variation in the body sizes of assemblages may be determined indirectly by the factors that influence geographical variation in species richness. © 2008 The Author Journal compilation

The establishment and maintenance of a system of protected areas is central to regional and global strategies for the conservation of biodiversity. The current global trend towards human population growth and widespread environmental degradation means that such areas are becoming increasingly isolated, fragmented habitat islands. In regions in which this process is well advanced, a high proportion of species are thus predicted to have become restricted to protected areas. Here, using uniquely detailed datasets for Britain, a region with close to the global level of percentage coverage by statutory protected areas, we determine the extent of restriction of species of conservation concern to these areas. On the basis of currently known distributions, more than a half of such species are highly dependent on protected areas for their continued persistence, occurring either entirely or largely within their bounds. Such coverage is of particular importance for those species with narrower distributions, and therefore, under the greatest threats, underlining the vital importance of adequately resourcing, maintaining, and developing protected areas to prevent these species from being lost.

We used data on the world's woodpeckers to test for patterns in the geographic distributions of a single group of closely related species. The frequency distribution of woodpecker geographic range sizes is approximately lognormal. Most variation in range sizes is explained by differences between species within genera; that is, range size seems to be an evolutionarily labile trait. The largest woodpecker ranges are found in Eurasia, both when absolute differences are compared and when range size is measured as a proportion of estimated available habitat. Notably, there is a negative relationship between the mean range sizes attained by species in a genus or tribe in South America and the mean ranges attained by species in the same tribe or genus in North America. Large-bodied species tend to be more widely distributed and to live at higher latitudes, but both tendencies disappear if the taxonomic relatedness of species is controlled for. Species living at high latitudes also tend to be more widely distributed. This relationship seems largely due to the effect of North American woodpeckers, which show it even when the taxonomic relatedness of species is controlled. Small continents generally have more woodpecker species than do large ones. Woodpecker geographic range sizes are smaller the more woodpecker species inhabit an area. Species show less overlap in their geographic ranges with species of similar than with species of dissimilar body size. The implications of these results for our understanding of patterns in geographic range sizes are discussed.

Evaluations of the effectiveness of protected areas often report their inadequate representation of regional variation in environmental conditions, land cover, and biological diversity. One frequent contributory explanation is the heavy reliance placed upon the designation of public as opposed to private lands for statutory protection. Given that protected area designation in Britain has no such constraint, and indeed that more than half of such areas are on private lands, we tested the a priori assumption that within this region the representation of environmental conditions and land cover within statutory protected areas would be more equitable. Despite the reduction in land ownership constraints on where protected areas can be established, a marked bias in protected area coverage remains. Protected areas in Britain tend toward regions of higher elevation, soils of lower economic potential, and coastal/estuarine habitat and fail adequately to represent areas of lower elevation and woodland habitats. Improving the current situation requires not only a more systematic approach to site selection, but a more equitable and diverse portfolio of incentives for private landowners to facilitate the decision to manage sites for conservation.

Systematic conservation planning provides a structured, target-driven approach to ensuring the long-term maintenance of biodiversity. However, reviews of how well the steps of such a planning process are applied in different regions are scant; some steps may be implemented although there is no formal systematic conservation planning process taking place. Here we conduct such a review for Europe. Taking in turn the six recognized steps of systematic conservation planning, for this region: (i) The availability of data on biodiversity remains a significant constraint on conservation planning because, although species occurrences have often been better mapped in Europe than elsewhere, there is a continuing mismatch between the spatial resolution at which data coverage is adequate and that of habitat fragmentation. (ii) Although there are important legal frameworks for conservation planning, explicit quantitative goals for the representation and persistence of biodiversity are largely lacking. (iii) Assessment of the effectiveness of existing protected area systems is patchy and rather ill developed, with a substantial gulf between the work being conducted in more academic and policy-oriented arenas. (iv) Nonetheless, particularly through the Natura 2000 process, there has been an extraordinary program to select additional protected areas. (v) Although it has taken longer than originally envisaged, this program is resulting in a substantial expansion of the protected area system. (vi) There are significant concerns over the extent to which existing protected area systems can maintain their biodiversity values, particularly given the small size of many of these areas and likely impacts of climate change.

Aim Using a global data base of the distribution of extant bird species, we examine the evidence for spatial variation in the evolutionary origins of contemporary avian diversity. In particular, we assess the possible role of the timing of mountain uplift in promoting diversification in different regions. Location Global. Methods We mapped the distribution of avian richness at four taxonomic levels on an equal-area 1° grid. We examined the relationships between richness at successive taxonomic levels (e.g. species richness vs. genus richness). We mapped the residuals from linear regressions of these relationships to identify areas that are exceptional in the number of lower taxa relative to the number of higher taxa. We use generalized least squares models to test the influence of elevation range and temperature on lower-taxon richness relative to higher-taxon richness. Results Peaks of species richness in the Neotropics were congruent with patterns of generic richness, whilst peaks in Australia and the Himalayas were congruent with patterns of both genus and family richness. Hotspots in the Afrotropics did not reflect higher-taxon patterns. Regional differences in the relationship between richness at successive taxonomic levels revealed variation in patterns of taxon co-occurrence. Species and genus co-occurrence was positively associated with elevational range across much of the world. Taxon occurrence in the Neotropics was associated with a positive interaction between elevational range and temperature. Conclusions These results demonstrate that contemporary patterns of richness show different associations with higher-taxon richness in different regions, which implies that the timing of historical effects on these contemporary patterns varies across regions. We suggest that this is due to dispersal limitation and phylogenetic constraints on physiological tolerance limits promoting diversification. We speculate that diversification rates respond to long-term changes in the Earth's topography, and that the role of tropical mountain ranges is implicated as a correlate of contemporary diversity, and a source of diversification across avian evolutionary history.

Sympatric speciation is now accepted as theoretically plausible and a likely explanation for divergence in a handful of taxa, but its contribution to large-scale patterns of speciation remains contentious. A major problem is that it is difficult to differentiate between alternate scenarios of geographic speciation when species ranges have shifted substantially in the past. Previous studies have searched for a signal of the geographic mode of speciation by testing for a correlation between time since speciation and range overlap. Here we use simulations to show that the proportion of species showing zero or complete range overlap are more reliable indicators of the geography of speciation than is the correlation between time since speciation and overlap. We then apply these findings to the distributions of 291 pairs of avian sister species. Although 49% of pairs show some overlap in their ranges, our simulations show that this is not surprising under allopatric models of speciation. More revealingly, less than 2% show complete range overlap. Our simulations demonstrate that the observed patterns are most consistent with a model in which allopatric speciation is dominant but in which sympatric speciation is also present and contributes 5% of speciation events.

The growing proportion of human populations living in urban areas, and consequent trends of increasing urban expansion and densification fuel a need to understand how urban form and land use affect environmental quality, including the availability of urban green spaces. Here we use Sheffield as a case study of city-wide relationships between urban green space extent, quality (vegetation cover and tree-cover), and gradients in urban form and topography. The total area of buildings and length of the road network are equally strong negative predictors of extent of green space, while the former predictor is a more important negative influence upon green space quality. Elevation positively influences extent of green space but negatively influences tree-cover. In contrast, slope of terrain positively influences green space quality and is the best predictor of tree-cover. Overall housing density is a more important negative predictor of extent of green space and tree-cover than the densities of individual housing types. Nevertheless, the latter are more important influences upon levels of vegetation cover. Threshold effects of densities of different housing types suggest opportunities for optimising green space quality, with implications for housing policy. Variation in ecological quality of green space may partly reflect different historical intensities of industrial activity.

The development of a more synthetic approach to understanding spatial patterns in biogeography, particularly of the way in which these patterns interact, constitutes a major challenge for the field. Here we propose some key elements of such a synthesis for what can broadly be termed ‘ecogeographical rules’, that is spatial patterns in biological traits. These include understanding: (1) the different kinds of patterns (intraspecific, interspecific and assemblage), and the distinctions between them; (2) the unifying role that geographical ranges play in linking the patterns together; (3) that this unification can be obscured by the methodological assumptions made in documenting some patterns (e.g. assuming that intraspecific variation does not significantly influence interspecific and assemblage patterns in traits); (4) the implications of other methodological issues for the nature of observed patterns (e.g. how ranges are located on positional or environmental axes for interspecific patterns); (5) the need for further development of models linking different types of traits; (6) the nature of the generality of documented patterns at all levels, and particularly the difference between the frequency with which patterns are documented in the literature and the variety of extant species; and (7) the constraints that the form of intraspecific patterns place on interspecific and assemblage patterns, and that interspecific patterns place on assemblage patterns.

Urbanisation has a profound effect on both people and the environment, as levels of physical activity decline and many natural ecosystems become lost or degraded. Here we draw on emerging research to examine the role of green spaces in providing a venue for outdoor physical activity, and in enhancing the benefit of a given amount of physical activity for urban residents. We identify critical knowledge gaps, including (1) whether (and for whom) levels of physical activity increase as new green spaces are introduced or old spaces reinvigorated; (2) which characteristics of nature promote physical activity; (3) the extent to which barriers to outdoor physical activity are environmental or social; and (4) whether the benefits of physical activity and experiences of nature accrue separately or synergistically. A clear understanding of these issues will help guide effective investment in green space provision, ecological enhancement and green exercise promotion.

Surveying threatened and invasive species to obtain accurate population estimates is an important but challenging task that requires a considerable investment in time and resources. Estimates using existing ground-based monitoring techniques, such as camera traps and surveys performed on foot, are known to be resource intensive, potentially inaccurate and imprecise, and difficult to validate. Recent developments in unmanned aerial vehicles (UAV), artificial intelligence and miniaturized thermal imaging systems represent a new opportunity for wildlife experts to inexpensively survey relatively large areas. The system presented in this paper includes thermal image acquisition as well as a video processing pipeline to perform object detection, classification and tracking of wildlife in forest or open areas. The system is tested on thermal video data from ground based and test flight footage, and is found to be able to detect all the target wildlife located in the surveyed area. The system is flexible in that the user can readily define the types of objects to classify and the object characteristics that should be considered during classification.

Light Detection and Ranging (LiDAR) systems are frequently used in ecological studies to measure vegetation canopy structure. Waveform LiDAR systems offer new capabilities for vegetation modelling by measuring the time-varying signal of the laser pulse as it illuminates different elements of the canopy, providing an opportunity to describe the 3D structure of vegetation canopies more fully. This article provides a comparison between waveform airborne laser scanning (ALS) data and discrete return ALS data, using terrestrial laser scanning (TLS) data as an independent validation. With reference to two urban landscape typologies, we demonstrate that discrete return ALS data provided more biased and less consistent measurements of woodland canopy height (in a 100% tree covered plot, height underestimation bias = 0.82 m; sd = 1.78 m) than waveform ALS data (height overestimation bias = −0.65 m; sd = 1.45 m). The same biases were found in suburban data (in a plot consisting of 100% hard targets e.g. roads and pavements), but discrete return ALS were more consistent here than waveform data (sd = 0.57 m compared to waveform sd = 0.76 m). Discrete return ALS data performed poorly in describing the canopy understorey, compared to waveform data. Our results also highlighted errors in discrete return ALS intensity, which were not present with waveform data. Waveform ALS data therefore offer an improved method for measuring the three-dimensional structure of vegetation systems, but carry a higher data processing cost. New toolkits for analysing waveform data will expedite future analysis and allow ecologists to exploit the information content of waveform LiDAR.

Concern has been expressed over societal losses of plant species identification skills. These losses have potential implications for engagement with conservation issues, gaining human wellbeing benefits from biodiversity (such as those resulting from nature-based recreational activities), and early warning of the spread of problematic species. However, understanding of the prevailing level of species identification skills, and of its key drivers, remains poor. Here, we explore socio-demographic factors influencing plant identification knowledge and ability to classify plants as native or non-native, employing a novel method of using real physical plants, rather than photographs or illustrations. We conducted face-to-face surveys at three different sites chosen to capture respondents with a range of socio-demographic circumstances, in Cornwall, UK. We found that survey participants correctly identified c.60% of common plant species, were significantly worse at naming non-native than native plants, and that less than 20% of people recognised Japanese knotweed Fallopia japonica, which is a widespread high profile invasive non-native in the study region. Success at naming plants was higher if participants were female, a member of at least one environmental, conservation or gardening organisation, in an older age group (than the base category of 18–29 years), or a resident (rather than visitor) of the study area. Understanding patterns of variation in plant identification knowledge can inform the development of education and engagement strategies, for example, by targeting sectors of society where knowledge is lowest. Furthermore, greater understanding of general levels of identification of problematic invasive non-native plants can guide awareness and education campaigns to mitigate their impacts.

The probability that protected areas will deliver their potential for maintaining or enhancing biodiversity is likely to be maximised if they are appropriately and effectively managed. As a result, governments and conservation agencies are devoting much attention to the management of protected areas. In the U.K., the demand for performance accountability has resulted in Public Service Agreements (PSA) that set out targets for government departments to deliver results in return for investments being made. One such target for England is to ensure that all nationally important wildlife sites are in favourable condition by 2010. Here, we tested the hypothesis, of potential strategic importance, that the ecological condition of these sites is predictable from relationships with a range of physical, environmental and demographic variables. We used binary logistic regression to investigate these relationships, using the results of English Nature’s 1997–2003 condition assessment exercise. Generally, sites in unfavourable condition tend to be larger in area, located at higher elevations, but with higher human population density and are more spatially isolated from units of the same habitat. However, despite the range of different parameters included in our models, the extent to which the condition of any given site could be predicted was low. Our results have implications for the delivery of PSA targets, funding allocation, and the location of new protected areas.

While there is intense debate regarding the impact of domestic cat populations on wildlife, its resolution is hindered by the lack of quite basic information. Domestic cats are generalist and obligate predators that receive supplementary food, and their population density reflects that of humans more than the density of their prey. In such a predator-prey system there is the potential for cat populations to have negative impacts on avian assemblages, which may be indicated by negative correlations between cat density and avian species richness and density. Here we report on the nature of such correlations across urban areas in Britain both for groups of species classified regarding their vulnerability to cat predation and individual species. Taking the availability of green space into account, we find negative relationships between cat densities and the number of bird species breeding in urban 1 km x 1 km squares. These relationships are particularly strong among groups of species that are vulnerable to cat predation. We find positive correlations between cat and avian densities; these have low explanatory power and shallow slopes among the species groups that are particularly vulnerable to cat predation. Evidence that the densities of individual species that are vulnerable to cat predation are negatively correlated with cat densities is equivocal, with at least half the species showing no marked pattern, and the remainder exhibiting contrasting patterns. Our results appear not to be confounded by the density of nest-predating corvids (carrion crow, magpie, and jay), as the density of these species was not strongly negatively correlated with avian species richness or density. The general lack of marked negative correlations between cat and avian densities at our focal spatial scale may be a consequence of consistently high cat densities in our study areas (minimum density is 132 cats per square kilometre), and thus uniformly high impacts of cat populations on urban avian assemblages.

This paper reviews broad geographical patterns in the species composition of breeding woodland bird communities from Ireland to eastern Europe and outlines how processes affecting woodland birds in Britain and Ireland may differ from those operating in mainland Europe. Bird communities in British and Irish woodlands consist of a subset of the species occurring within European forests at similar latitudes. The occurrence of virtually all groups of forest birds is lower in Britain, and strikingly lower in Ireland, than in other temperate areas of mainland Europe. This phenomenon appears to form part of a west–east gradient in species diversity and is probably not just a consequence of insularity. Across this gradient there appears to be broad geographical constancy in the types (taxonomic, ecological and life-history groups) of species present. There is considerable spatial variation in habitat use by forest species within Europe. Some species in Britain probably use habitats in different ways to elsewhere for reasons related to competition, predation and historical adaptation to landscape change. Several species appear to reach the limits of their geographical ranges within Britain (i.e. in the absence of physical barriers). We suggest that range contraction of one of these species, the Common Nightingale Luscinia megarhynchos, in Britain may partially reflect redistribution into the highest quality areas in response to a wider population decline. It is argued that conclusions drawn from studies of forest birds in Britain do not necessarily apply in other regions and vice versa. There is a need for large-scale studies in Europe of the spatial variation in organization of forest bird assemblages, habitat use and the genetic structure of populations.

Green spaces play a crucial role in supporting urban ecological and social systems, a fact recognised in public policy commitments in both the UK and Europe. The amount of provision, the distribution of green space and the ease of access to such spaces are key contributors to social and ecological function in urban environments. We measured distance along the transport network to public green space available to households in Sheffield, and compared this with the distribution of private garden space. In addition, we used a geodemographic database, Mosaic UK, to examine how access to green space varies across different sectors of society. Public green spaces are chronically underprovided relative to recommended targets. For example, 64% of Sheffield households fail to meet the recommendation of the regulatory agency English Nature (EN), that people should live no further than 300 m from their nearest green space. Moreover, this figure rises to 72% if we restrict attention to municipal parks recognised by the local council. There is an overall reduction in coverage by green space when moving from neighbourhoods where green space is primarily publicly provided to those where it is privately provided. While access to public green space varies significantly across different social groups, those enjoying the greatest access include more deprived groups and older people. This study highlights the need for additional green space to be created and existing green space to be protected in light of increasing development pressure.

Households across the developed world cumulatively spend many millions of dollars annually on feeding garden birds. While beneficial effects on avian assemblages are frequently claimed, the relationships between levels of garden bird feeding and local avian populations are unknown. Using data from a large UK city, we show that both avian species richness and abundance vary across different socioeconomic neighbourhood types. We examined whether patterns in bird feeding could explain this variation. The density of bird feeding stations across the urban environment was strongly positively related to avian abundance, after controlling for differences in habitat availability. This effect was almost exclusively driven by the abundance of those species known to utilize garden feeding stations frequently. In contrast, the density of feeding stations had no effect on avian species richness. We also examined variation in the proportion of households in different communities that provide food for birds, a factor that is not correlated with feeder density. The prevalence of bird feeding across different neighbourhoods declined as socioeconomic deprivation increased, and increased with avian species richness and abundance. Our results suggest that the provision of supplementary food for birds by multiple landowners across a city can impact the status of urban bird populations. The potential for harnessing these actions for conservation needs to be explored.

() M2 where M1 and M2 are the total numbers of cells for map 1 and map 2, respectively, and m1 and m2 are the numbers of occupied cells of the respective maps. Critically, this empirical approach has been shown in practice to work well, or at least substantially better than existing alternatives, for estimating the abundances of

1. Spatial and temporal patterns in functional diversity can reveal the patterns and processes behind community assembly and whether ecological redundancy exists. Here, we analyse functional diversity in British avian assemblages over a period of about 20 years. 2. Functional diversity is generally lower than expected by chance, indicating that assemblages contain species with relatively similar functional traits. One potential explanation is filtering for traits suitable to particular habitats, though other explanations exist. 3. There was no evidence of ecological redundancy over the 20 years. In fact, changes in functional diversity were almost exactly proportional to changes in species richness. 4. The absence of functional redundancy results from little redundancy intrinsic to the species' functional relationships and also because compositional change was nonrandom. Observed extinction and colonization events caused greater changes in functional diversity than if these events were random. 5. Our findings suggest that community assembly is influenced by the traits of species and that observed changes in functional diversity provide no reason to believe that the functioning of natural systems is buffered against change by ecological redundancy.

Patterns and changes in functional diversity can inform about spatial and temporal variation in trait diversity, about the processes that drive assembly, and whether assemblages are likely to contain redundant species. We recently provided a new measure (termed FD) and detailed its advantages over previous ones. Since then an increasing amount of research effort has been directed towards both developing appropriate measures of functional diversity and critiquing previous ones, including FD. Podani and Schmera (2006) attempt to do both, though here we argue that they accomplish neither. First, they suggest that a particular distance measure and clustering method are appropriate. We suggest that this is not the case, and show that they may have little effect on quantitative patterns in FD. Second, they suggest that values of functional diversity must be insensitive to the number of functional traits used. We do not agree because we can envisage no relevant ecological question. Third, they observe that we originally defined an FD of zero for an empty assemblage, whereas it is more appropriate for single species assemblages to have FD of zero. We agree. Their solution, however, is to create a measure of functional diversity which violates set monotonicity. Our solution is a revised version of FD for which single species assemblages have FD =0, and which does not violate set monotonicity. In conclusion, we are confident that FD behaves appropriately and note that it remains the measure of functional diversity with greatest power to explain variation in ecosystem functioning.

The role of domestic cats Felis catus in the troubling, on-going decline of many urban bird populations in the UK is controversial. Debate, in the UK and elsewhere, has centred on the level of avian mortality directly imposed by cats, and on whether this is principally compensatory (the ‘doomed surplus’ hypothesis) or additive (the ‘hapless survivor’ hypothesis). However, it is well established that predators also have indirect, sub-lethal effects on their prey where life-history responses to predation risk affect birth and death rates. Here, using a simple model combining cat predation on birds with a sub-lethal (fear) effect of cat density on bird fecundity, we show that these sub-lethal effects may be substantial for urban songbirds. When cat densities are as high as has been recorded in the UK, and even when predation mortality is low (e.g.

Increasing housing density is an important component of global land transformation, with major impacts on patterns of biodiversity. However, while there have been many studies of the changes in biodiversity across rural–urban gradients, which are influenced in large part by housing densities, how biodiversity changes across the full range of regional variation in housing density remains poorly understood. Here, we explore these relationships for the richness and abundance of breeding birds across Britain. Total richness, and that of 27 urban indicator species, increased from low to moderate household densities and then declined at greater household densities. The richness of all species increased initially faster with household density than did that of the urban indicator species, but nonurban indicator species richness declined consistently after peaking at a very low housing density. Avian abundance showed a rather different pattern. Total abundance and that summed across all urban indicator species increased over a wide range of household densities, and declined only at the highest household densities. The abundance of individual urban indicator species generally exhibited a hump-shaped relationship with housing density. While there was marked intraspecific variation in the form of such relationships, almost invariably avian abundance declined at housing densities below that at which the UK government requires new developments to be built. Our data highlight the difficulties of maintaining biodiversity while minimising land take for new development. High-density housing developments are associated with declines in many of those species otherwise best able to exploit urban environments, and those components of native biodiversity with which human populations are often most familiar.

Two consequences of the continued urbanisation of the human population are that a growing proportion of the landscape is less hospitable to, and that a growing proportion of people are disconnected from, native biodiversity. One response of the UK government has been to establish a goal, and an associated baseline indicator, of increasing the extent and range of public participation in gardening for wildlife. The formulation of policy to attain this end requires, however, insight into the factors that are associated with the level of participation. Here we examine the relationships, across 15 areas in five UK cities, between the proportion of households providing various garden features for wildlife or participating in various wildlife gardening activities, and housing densities and characteristics of the garden resource. We show that significant numbers of households participate in some form of wildlife gardening, but that the predominant form this participation takes is feeding wild birds. Key variables associated with spatial variation in wildlife gardening activities are the proportion of households with access to a garden and, more importantly, average garden size and the proportion of land cover by gardens. There was no evidence for strong effects of household density or the socio-economic status of householders on the prevalence of wildlife friendly features in gardens or on the participation by householders in activities to encourage wildlife. Our results suggest important considerations in attempts to increase awareness and participation in wildlife gardening.

Aim To assess whether spatial variation in sampling effort drives positive correlations between human population density and species richness. Location British 10 × 10 km squares. Methods We calculated three measures of species richness from atlas data of breeding birds in Britain: total species richness, species richness standardised for sampling effort, and the number of species only recorded in supplementary casual records in a manner not standardised for survey effort. We then assessed the form of the relationship between these richness estimates and human population density, both with and without taking spatial autocorrelation into account. Results Both total and standardised species richness exhibit similar species richness–human population density relationships; species richness generally increases with human population density, but decreases at the very highest densities. Supplementary species richness is very weakly correlated with human population density. Main conclusions In this example, sampling effort only slightly influences the form of species richness–human population density relationships. The positive correlation between species richness and human population density and any resultant conservation conflicts are thus not artefactual patterns generated by confounding human density and sampling effort.