Variation In Habitat Quality Research Articles

Spatial variation in haemoglobin concentration of nestling Blue Tits (Cyanistes caeruleus): a long-term perspective

An understanding of the influences of anthropogenic disturbance and variation in habitat quality on organism condition and breeding success may improve future management and conservation decisions. Some authors consider haemoglobin concentration to be a simple biochemical indicator of bird condition. The main goal of this paper is to examine if the level of haemoglobin displays any consistent pattern of variation across habitats differing in quality. We present results concerning long-term variation in haemoglobin concentration in the blood of about 14-day-old nestling Blue Tits (Cyanistes caeruleus) in central Poland in an 11-year period (2003–2013), in two landscapes (an urban parkland and a deciduous forest). The most important findings of the study are: (1) the concentration of haemoglobin of the nestlings from the same brood tended to be consistently similar, with most variation occurring between broods, (2) mean levels of haemoglobin varied between years, and were correlated with caterpillar abundance peaks in the forest study site, (3) mean haemoglobin concentration was significantly higher in the forest area than in the parkland area, (4) haemoglobin levels were positively correlated with breeding and fledging success. We confirmed that haemoglobin concentration displays a spatio-temporal pattern and that the level of haemoglobin is a reliable condition and habitat quality indicator in nestling Blue Tits in the study populations. Although, strictly speaking, the analysed differences are between two particular sites, we think that they reflect differences between urban and non-urban habitats.

The relative importance of habitat quality and landscape context for reptiles in regenerating landscapes

Restoration activities are limited by funding and logistics. To optimise restoration efforts, we need to evaluate the effects of management actions on wildlife populations. In general, site-scale habitat quality has a stronger influence on habitat use by fauna than the landscape context. However, this is yet to be empirically tested for reptiles. In this study, we used model averaging and hierarchical partitioning to compare the relative importance of site-scale habitat quality and landscape context for reptile communities and species in a regenerating woodland landscape in semi-arid Queensland, Australia. Reptiles were surveyed at 55 sites. Habitat quality was assessed using relevant variables based on published habitat-associations for each species or group. Landscape context was assessed using binary, mosaic and continuous descriptions of vegetation cover within 250m of the survey sites. We found that, in comparison to site-scale habitat quality, the composition of the surrounding landscape had little influence on reptiles, despite testing three alternative approaches for describing landscape context. Nine out of eleven reptile species and groups responded to variation in habitat quality, whereas just one species responded to variation in landscape context. Species richness, diversity, and abundance were unaffected by landscape context, but were influenced by site-scale structural complexity and vegetation type. Our findings suggest that reptiles, in general, benefit from conservation and restoration activities that focus on improving site-scale habitat quality, with increasing the amount and connectivity of surrounding vegetation of lesser value. This study also highlights the importance of better understanding the drivers of reptile distributions and abundances in dryland landscapes.

Assessing baseline stress physiology as an integrator of environmental quality in a wild avian population: Implications for use as a conservation biomarker

Stress hormones (i.e., glucocorticoids such as corticosterone and cortisol) have been widely proposed as biomarkers of habitat quality and disturbance. However, there is growing evidence that baseline glucocorticoid (GC) levels are highly context-dependent, potentially confounding their utility for inferring population-level disturbance depending on the life history stage and the duration, severity, and type of environmental change being measured. Determining which aspects of an organism's environment are consistently reflected by baseline GC levels is therefore of paramount importance to establishing how they may be best suited to conservation monitoring goals. We investigated the relationship between baseline GC levels and three extrinsic (food availability, inter-specific nest competition, intra-specific competition) and two intrinsic (reproductive investment, body condition) environmental contexts in breeding female tree swallows (Tachycineta bicolor) at two reproductive stages. We combined this with a manipulation of energetic demand (i.e., a decrease in foraging profitability) to determine whether baseline GCs reflect the extrinsic or intrinsic environment when females are faced with an unexpected disturbance. Baseline GC levels were not reflective of any environmental component in control females, regardless of reproductive stage. However, levels increased and were reflective of a decrease in body mass when females were challenged during the offspring provisioning period. Our findings suggest that baseline GCs may not always be indicative of the environmental contexts we associate with variation in habitat quality, particularly when individuals are operating within their expected energetic demand. In a conservation sense, baseline GCs may be more valuable in reflecting unexpected perturbations, which could limit their applicability as sensitive, predictive biomarkers across a diversity of systems.

Habitat quality versus spatial variables as determinants of small mammal assemblages in Atlantic Forest fragments

AbstractFragment size, isolation, and matrix properties have received considerable attention as predictors of species richness, abundance, and composition in habitat patches. However, measurements of habitat attributes or habitat quality are more directly related to the proximate effects of habitat fragmentation and may be more determinant of assemblages than traditional explanatory variables at local scales. We determine how habitat structure in fragments—a measure of habitat quality—compares to fragment size, isolation, and matrix properties as determinants of richness, abundance, and composition of non-volant small mammals in a fragmented landscape of Atlantic Forest. Small mammals were surveyed once in 25 fragments in the Macacu River watershed, Rio de Janeiro, Brazil, from 1999 to 2001 and 2005 to 2009. A total of 83 candidate models were formulated and compared by Akaike Information Criteria. Habitat structure was one of the main determinants of small mammal assemblages in fragments, as important as fragment isolation for species composition and climatic season for species richness. Rodents were more abundant in fragments with increased overstory and understory vegetation density and more fallen logs. The contrary pattern was found for overall species richness and for species of terrestrial habit, which were more abundant in fragments with more open forest: decreased overstory and understory vegetation density and less fallen logs. Habitat quality in fragments may be a more important determinant of assemblages of small mammals and other vertebrates than previously considered in landscape and land use studies.O tamanho e isolamento dos fragmentos e as propriedades da matriz têm recebido considerável atenção como preditores da riqueza, abundância e composição de espécies em manchas de habitat. Entretanto, medidas dos atributos do habitat ou da qualidade do habitat são mais diretamente relacionadas aos efeitos imediatos da fragmentação de habitat, e seriam mais determinantes das comunidades do que as variáveis explicativas tradicionais. Determinamos como a estrutura do habitat nos fragmentos—uma medida da qualidade do habitat—se compara ao tamanho e isolamento dos fragmentos, e às propriedades da matriz como determinantes da riqueza, abundância e composição de espécies de pequenos mamíferos não-voadores em uma paisagem fragmentada de Mata Atlântica. Os pequenos mamíferos foram amostrados uma vez em 25 fragmentos na Bacia do Rio Macacu, Rio de Janeiro, Brasil, de 1999 a 2001 e de 2005 a 2009. Um total de 83 modelos foram formulados e comparados utilizando o Critério de Informação de Akaike. A estrutura do habitat foi um dos principais determinantes das comunidades de pequenos mamíferos nos fragmentos de mata, tão importante quanto o isolamento entre fragmentos para a composição de espécies e os efeitos das estações climáticas sobre a riqueza de espécies. Os roedores foram mais abundantes nos fragmentos com estratificação vertical e sub-bosque mais densos e com maior presença de troncos caídos. O padrão contrário foi encontrado para a riqueza total de espécies e para espécies de hábito terrestre, que foram mais abundantes em fragmentos com estratificação vertical e sub-bosque menos densos e menor presença de troncos caídos. A qualidade do habitat em fragmentos pode ser determinante das comunidades de pequenos mamíferos e outros vertebrados, mais importante do que considerado previamente em estudos de paisagens e uso da terra.

Evolution of natal and breeding dispersal: when is a territory an asset worth protecting?

Evolutionary models of dispersal frequently lack explicit reference to the age or sex of the individuals that disperse. This contrasts with reality where dispersal behavior strongly depends on individuals’ state, including age. To study why natal dispersal occurs more commonly than breeding dispersal, we investigate the interplay of 2 categories of explanation: the asset-protection principle (APP) and the “multiplier effect” (ME). The APP states that adults in possession of territories should be more reluctant to disperse. According to the ME, the simple fact of being born tells individuals that the site is of high quality, which may promote philopatry. Our model is set in habitats of spatially varying quality and individuals express different dispersal rates depending on state (life-history stage, sex, and quality of residential habitat). The model considers the accuracy of information about habitat quality, the proportion of good quality habitat, and the magnitude of habitat quality variation. We show that the predictions of the APP hold, but only when the “invisible” asset of likely future prospects in the current habitat is taken into account. Effects of the ME are consistently harder to detect, mainly due to density dependency overriding the benefits of habitat quality. We predict higher natal than breeding dispersal when territorial vacancies are scarce, and more variable breeding than natal dispersal when they are common.

Habitat and water quality variables as predictors of community composition in an Indonesian coral reef: a multi-taxon study in the Spermonde Archipelago

Assemblages of corals, sponges, foraminifera, sediment bacteria and sediment archaea were assessed at two depths in the Spermonde Archipelago. Our goal was to assess to what extent variation in composition could be explained by habitat and water quality variables. The habitat variables consisted of depth, substrate type and scleractinian coral cover while water quality variables were derived from ocean color satellite imagery, including the colored dissolved organic matter index (CDOM), chlorophyll-a (Chlor-a) and remote sensing reflectance at 645nm (Rrs_645). Together, habitat and water quality variables explained from 31% (sediment bacteria) to 80% (forams) of the variation in composition. The variation in composition of corals, sponges, forams and sediment archaea was primarily related to habitat variables, while the variation in composition of sediment bacteria was primarily related to water quality variables. Habitat and water quality variables explained similar amounts of variation in the composition of corals and sediment bacteria. CDOM (sponges, sediment bacteria and sediment archaea), Chlor-a (corals and forams) and Rrs_645 (sponges and forams) proved significant predictors of variation in composition for the studied taxa. In addition to water quality variables, all taxa responded to a range of habitat variables including depth and the percentage cover of various benthic life forms including coral cover variables, rubble and sand. Sand cover was the most important habitat variable for corals, sponges, sediment bacteria and sediment archaea. Coral life forms including the cover of branching and tabular corals were important habitat variables for sponges and forams. These results show marked differences in how various taxa respond to variation in habitat and water quality in the Spermonde Archipelago. Moreover, our results indicate that variables estimated from ocean color satellite imagery proved to be better predictors of variation in marine community composition than commonly-used proxies such as the distance offshore or distance to the nearest river.

Physiology in the service of fisheries science: Why thinking mechanistically matters

Behavioral responses of fishes to variability in environmental conditions and habitat quality are central to population-level demographic processes. Although field surveys can correlate abundance to habitat variables (physiochemical, biotic, and structural), they cannot provide mechanistic explanations. Moreover, field surveys are often stratified by time or geographic criteria relevant to humans, whereas fishes stratify by habitat variables relevant to them. If mechanisms underlying behavior are not explicitly understood, conclusions based on survey data can lead to biased inferences as to species-specific habitat requirements and preferences, as well as changes in stock size occurring over time. Because physiology is the transfer function that links specific environmental conditions to behavior and fitness, we argue great gains can be made through the integration of physiology and fisheries science. These are complementary disciplines, albeit ones that generally function at very different temporal and spatial scales, as well as different levels of biological organization. We argue more specifically that integrating physiological approaches with behavioral studies and traditional fisheries survey data (where each approach develops hypotheses to be tested in the other) can mechanistically link processes from cells through populations to place fisheries management in an appropriate ecosystem context. We further contend that population- and species-specific mechanistic understanding of physiological abilities and tolerances can significantly help to: improve stock assessments, describe essential fish habitat, predict rates of post-release mortality, develop effective bycatch reduction strategies, and forecast the population effects of increases in global temperatures and ocean acidification.

The Effects of Habitat Type and Volcanic Eruptions on the Breeding Demography of Icelandic Whimbrels Numenius phaeopus.

Distinct preference of species for habitats is most often driven by long term differences in demographic rates between habitats. Estimating variation in those rates is key for developing successful conservation strategies. Stochastic events can interact with underlying variation in habitat quality in regulating demography but the opportunities to explore such interactions are rare. Whimbrels in Iceland show a strong preference for sparsely vegetated riverplains. Such habitats in Iceland face various threats, e.g., climate change, river regulation and spread of alien plant species. In this study we compared demographic parameters of breeding Whimbrels between riverplains and other habitats before, during and after volcanic eruption events to estimate the importance of the habitats for the species and the effect of ash deposit on breeding success. We found that an estimated minimum of 23% of the Icelandic population of Whimbrels and c. 10% of the world population of the species breed in riverplain habitats in Iceland. Whimbrels bred consistently at much higher densities in riverplain habitats than in other habitats and riverplains also had higher densities of pairs with fledglings although the proportion of successful breeders was similar between habitats. Predation by livestock may have had a considerable negative effect on breeding success on our study sites. Breeding was negatively affected by the volcanic activity, probably through the effects of ash on the invertebrate food supply, with breeding success being gradually worse closer to the eruption. Breeding success was equally affected by volcanism across habitats which differed in underlying habitat quality. This study gives an example of how populations can be regulated by factors which operate at different spatial scales, such as local variation in habitat quality and stochastic events which impact larger areas.

Effects of neutrality, geometric constraints, climate, and habitat quality on species richness and composition of Atlantic Forest small-mammals

Aim To compare the fit of models of climate, habitat quality, neutral processes, and geometric constraints to species richness and composition of small mammal assemblages. Location The South American Atlantic Forest biome. Methods Using neutral models and mid-domain effect models, we simulated species spread in a spatially explicit array of grid cells representing the Atlantic Forest domain. We compared empirical patterns of species richness and composition with predictions of the neutral and mid-domain effect models. We also modeled individual species responses to climatic conditions and forest integrity, a measure of habitat quality. Results Habitat quality was the single best predictor of local species richness (α-diversity), but was a poor predictor of local species composition and of the decay in species similarity with distance (β-diversity). The neutral and mid-domain models generated very similar predictions, and were better predictors of species composition than of species richness. Climate variables were also strongly associated with overall species composition, but not with species richness. Main Conclusions The species richness of small-mammal assemblages in the Atlantic Forest is best explained by variation in habitat quality. In contrast, the composition of small-mammal assemblages is best explained by models of limited dispersal (neutral and mid-domain) and effects of climate on local species composition. Collectively, these results suggest that regional patterns of species richness may be uncoupled from patterns of species composition. Both species richness and composition should be considered when evaluating the predictions of neutral and mid-domain effect models, and of correlations of community structure with climatic or habitat variables.

The effects of habitat availability and quality on small mammals abundance in the Brazilian Atlantic Forest

Different causal mechanisms have been suggested to explain species decline in fragmented landscapes, mainly those related with the amount and configuration of habitat for species (habitat availability), and those related with the habitat patch quality. Here we quantify the effects of habitat availability and quality on the abundance of three small mammals in a landscape at the Brazilian Atlantic Forest. We compared species with different habitat preferences and dispersal abilities (Nectomys squamipes, Marmosa paraguayana and Didelphis aurita). The most sensitivity species to fragmentation (N. squamipes) was affected by habitat quality variables only, while the least sensitive species (D. aurita) did not suffer any effect of habitat quality and availability. M. paraguayana, a species with an intermediate degree of sensitivity, responded to both habitat quality and availability. We recommend combining information on both habitat availability and quality to unravel species persistence in fragmented landscapes.

In situ adaptive response to climate and habitat quality variation: spatial and temporal variation in European badger (Meles meles) body weight.

Variation in climatic and habitat conditions can affect populations through a variety of mechanisms, and these relationships can act at different temporal and spatial scales. Using post-mortem badger body weight records from 15 878 individuals captured across the Republic of Ireland (7224 setts across ca. 15 000 km(2) ; 2009-2012), we employed a hierarchical multilevel mixed model to evaluate the effects of climate (rainfall and temperature) and habitat quality (landscape suitability), while controlling for local abundance (unique badgers caught/sett/year). Body weight was affected strongly by temperature across a number of temporal scales (preceding month or season), with badgers being heavier if preceding temperatures (particularly during winter/spring) were warmer than the long-term seasonal mean. There was less support for rainfall across different temporal scales, although badgers did exhibit heavier weights when greater rainfall occurred one or 2 months prior to capture. Badgers were also heavier in areas with higher landscape habitat quality, modulated by the number of individuals captured per sett, consistent with density-dependent effects reducing weights. Overall, the mean badger body weight of culled individuals rose during the study period (2009-2012), more so for males than for females. With predicted increases in temperature, and rainfall, augmented by ongoing agricultural land conversion in this region, we project heavier individual badger body weights in the future. Increased body weight has been associated with higher fecundity, recruitment and survival rates in badgers, due to improved food availability and energetic budgets. We thus predict that climate change could increase the badger population across the Republic of Ireland. Nevertheless, we emphasize that, locally, populations could still be vulnerable to extreme weather variability coupled with detrimental agricultural practice, including population management.

Wolves adapt territory size, not pack size to local habitat quality.

1. Although local variation in territorial predator density is often correlated with habitat quality, the causal mechanism underlying this frequently observed association is poorly understood and could stem from facultative adjustment in either group size or territory size. 2. To test between these alternative hypotheses, we used a novel statistical framework to construct a winter population-level utilization distribution for wolves (Canis lupus) in northern Ontario, which we then linked to a suite of environmental variables to determine factors influencing wolf space use. Next, we compared habitat quality metrics emerging from this analysis as well as an independent measure of prey abundance, with pack size and territory size to investigate which hypothesis was most supported by the data. 3. We show that wolf space use patterns were concentrated near deciduous, mixed deciduous/coniferous and disturbed forest stands favoured by moose (Alces alces), the predominant prey species in the diet of wolves in northern Ontario, and in proximity to linear corridors, including shorelines and road networks remaining from commercial forestry activities. 4. We then demonstrate that landscape metrics of wolf habitat quality - projected wolf use, probability of moose occupancy and proportion of preferred land cover classes - were inversely related to territory size but unrelated to pack size. 5. These results suggest that wolves in boreal ecosystems alter territory size, but not pack size, in response to local variation in habitat quality. This could be an adaptive strategy to balance trade-offs between territorial defence costs and energetic gains due to resource acquisition. That pack size was not responsive to habitat quality suggests that variation in group size is influenced by other factors such as intraspecific competition between wolf packs.

Experimental food supplementation reveals habitat-dependent male reproductive investment in a migratory bird.

Environmental factors can shape reproductive investment strategies and influence the variance in male mating success. Environmental effects on extrapair paternity have traditionally been ascribed to aspects of the social environment, such as breeding density and synchrony. However, social factors are often confounded with habitat quality and are challenging to disentangle. We used both natural variation in habitat quality and a food supplementation experiment to separate the effects of food availability-one key aspect of habitat quality-on extrapair paternity (EPP) and reproductive success in the black-throated blue warbler, Setophaga caerulescens. High natural food availability was associated with higher within-pair paternity (WPP) and fledging two broods late in the breeding season, but lower EPP. Food-supplemented males had higher WPP leading to higher reproductive success relative to controls, and when in low-quality habitat, food-supplemented males were more likely to fledge two broods but less likely to gain EPP. Our results demonstrate that food availability affects trade-offs in reproductive activities. When food constraints are reduced, males invest in WPP at the expense of EPP. These findings imply that environmental change could alter how individuals allocate their resources and affect the selective environment that drives variation in male mating success.

Patterns of year-to-year variation in haemoglobin and glucose concentrations in the blood of nestling Pied Flycatchers Ficedula hypoleuca

Physiological tools can be used to identify the sources and consequences of stressors on animals. Understanding the influences of variation in habitat quality and anthropogenic disturbance on organism condition and health may improve future management and conservation. We present results concerning variation in haemoglobin and glucose concentrations in the blood of about 14-day-old nestling Pied Flycatchers Ficedula hypoleuca in central Poland over a 4-year period, 2011–2014, in a deciduous forest. The most important findings of the study are: (1) the concentration of haemoglobin and glucose of the nestlings from the same brood tended to be consistently similar, with much variation occurring among broods; (2) repeatability of haemoglobin concentration was higher than repeatability of glucose concentration; (3) mean levels of haemoglobin and glucose varied among years; (4) haemoglobin and glucose concentrations were negatively correlated; and (5) there was a positive relationship between haemoglobin levels and breeding success.

The links between river morphological variables and benthic invertebrate assemblages: comparison among three European ecoregions

Understanding the relationship between river natural and degraded habitats and river assemblages is crucial but yet insufficient for the desired sustainable river management. Our paper therefore compares the relation of river natural morphological features and their modification to benthic invertebrate assemblages among European ecoregions Alps, Pannonian lowland, and Dinaric western Balkan with varied natural characteristics. Morphological conditions were assessed using the habitat quality (RHQ) and modification (RHM) variables, according to Slovenian hydromorphological assessment method, and linked to benthic invertebrate assemblages using multivariate analyses. The overall results indicate markedly higher importance of RHQ variables in comparison with RHM variables for structuring benthic invertebrate assemblages, but reveal important differences among ecoregions. Predominant flow and predominant channel substrate were found among the most important RHQ variables across all ecoregions. Beside these, benthic invertebrate assemblages of the Alps were influenced most by bank variables, whereas of the Pannonian lowland by features linked directly to channel conditions. In Dinaric western Balkan a combination of bank and channel variables influenced the assemblages. Among habitat modification features artificial bank profiles appeared important across all ecoregions. However, in the Alps equal explanatory power was observed for variables water impoundment by weir/dam and bank modifications, whereas in the Pannonian lowland only for variable artificial bank material and even for none in Dinaric western Balkan. According to our findings it is important to consider habitat modification in river management, but more weight should be given to habitat quality features. Moreover, the differences among ecoregions emphasize the need for ecoregion-specific approach.

Spatially variable habitat quality contributes to within-population variation in reproductive success.

Variation in habitat quality is common across terrestrial, freshwater, and marine habitats. We investigated how habitat quality influenced the reproductive potential of mud crabs across 30 oyster reefs that were degraded to different extents. We further coupled this field survey with a laboratory experiment designed to mechanistically determine the relationship between resource consumption and reproductive performance. We show a >10-fold difference in average reproductive potential for crabs across reefs of different quality. Calculated consumption rates for crabs in each reef, based on a type II functional response, suggest that differences in reproductive performance may be attributed to resource limitation in poor quality reefs. This conclusion is supported by results of our laboratory experiment where crabs fed a higher quality diet of abundant animal tissue had greater reproductive performance. Our results demonstrate that spatial variation in habitat quality can be a considerable contributor to within-population individual variation in reproductive success (i.e., demographic heterogeneity). This finding has important implications for assessing population extinction risk.

Behavioral and physiological responses of American black bears to landscape features within an agricultural region

Human activities and variation in habitat quality and configuration have been shown to influence space use patterns in many species, but few studies have documented the physiological responses of free‐ranging animals to these factors. We combined remote biologger technology, capturing continuous heart rate values, with locational data from GPS collars to investigate the behavioral and physiological reactions of American black bears (Ursus americanus) to a landscape dominated by agriculture (52.5% areal cover). Our study occurred at the edge of the range of this species, with small, scattered patches of forest within a mosaic of crop fields and an extensive road network. However, only ~2–4% of the area contained crops that bears consumed (corn, sunflowers, oats). We used GPS locations to identify the habitat that bears occupied, and to estimate their rates of travel. Heart rates increased with movement rates, rising by over 30% from resting rate to their fastest travel speeds. We used a modeling approach to distinguish among factors that influenced heart rates independent of movement rates. Bears commonly crossed agricultural areas that provided no food or cover and their heart rates, elevated beyond what was expected from their movement rate, were indicative of a stress response. However, when bears entered agricultural areas composed of edible crops, many individuals showed reduced movement and slower heart rates, suggesting that bears foraging there felt at ease or crops allow bears to more easily forage due to their dense spatial arrangements. Unexpectedly, female bears elicited lower heart rates and lower levels of activity in the most fragmented patches of natural habitat, possibly a sign of human‐avoidance behavior or a reaction related to crossing roads. During fall, as bears prepared for hibernation, their heart rates declined two weeks before their movements slackened, evidence that metabolism slowed to enhance fat accumulation; they also shifted to a nocturnal activity pattern, likely to reduce exertion during the heat of the day. The use of a physiological monitor provided new insights on bear biology and ecology that would not have otherwise been apparent.

Dispersal evolution and resource matching in a spatially and temporally variable environment.

Metapopulations may consist of patches of different quality, and are often disturbed by extrinsic processes causing variation of patch quality. The persistence of such metapopulations then depends on the species' dispersal strategy. In a temporally constant environment, the evolution of dispersal rates follows the resource matching rule, i.e. at the evolutionarily stable dispersal strategy the number of competitors in each patch matches the resource availability in each patch. Here, we investigate how the distribution of individuals resulting from convergence stable dispersal strategies would match the distribution of resources in an environment which is temporally variable due to extrinsic disturbance. We develop an analytically tractable asexual model with two qualities of patches. We show that convergence stable dispersal rates are such that resource matching is predicted in expectation before habitat quality variation, and that the distribution of individuals undermatches resources after habitat quality variation. The overall flow of individuals between patches matches the overall flow of resources between patches resulting from environmental variation. We show that these conclusions can be generalized to organisms with sexual reproduction, and to a metapopulation with three qualities of patches when there is no mutational correlation between dispersal rates.

The effect of temperature and habitat quality on abundance of the Glanville fritillary on the Isle of Wight: implications for conservation management in a warming climate

Creating variation in microclimates through habitat management is often advocated as a way of ameliorating the impact of climate warming, although the effectiveness of microclimate management has rarely been studied. We compared temporal variation in habitat quality (the availability of suitably warm microclimates) and ambient air temperature on the abundance of a highly thermophilous species of butterfly, the Glanville fritillary Melitaea cinxia, at one site on the south coast of the Isle of Wight, UK, from 1997 to 2010. Ground temperatures beneath the various habitat successional stages were measured and compared, and the relationship between butterfly abundance and hostplant and weather variables was examined. Temporal variation in habitat quality was almost twice as strong as a predictor of butterfly abundance as ambient air temperature. We found no relationship between abundance and rainfall. Comparisons of ground temperatures beneath habitats showed that earlier successional stages were considerably warmer than later successional stages, and the distribution of Glanville fritillary larval ‘webs’ within plots was restricted to these warmer habitats. Hostplants selected for oviposition by gravid females were also considerably warmer than ambient temperature. The importance of habitat quality reinforces the notion that thermophilous insects would benefit from site management practices that create thermally diverse environments. Heterogeneous habitats provide refugia for species intolerant of climate change, as well as opportunities for range expansion.

Very high resolution Earth observation features for monitoring plant and animal community structure across multiple spatial scales in protected areas

Monitoring the status and future trends in biodiversity can be prohibitively expensive using ground-based surveys. Consequently, significant effort is being invested in the use of satellite remote sensing to represent aspects of the proximate mechanisms (e.g., resource availability) that can be related to biodiversity surrogates (BS) such as species community descriptors. We explored the potential of very high resolution (VHR) satellite Earth observation (EO) features as proxies for habitat structural attributes that influence spatial variation in habitat quality and biodiversity change. In a semi-natural grassland mosaic of conservation concern in southern Italy, we employed a hierarchical nested sampling strategy to collect field and VHR-EO data across three spatial extent levels (landscape, patch and plot). Species incidence and abundance data were collected at the plot level for plant, insect and bird functional groups. Spectral and textural VHR-EO image features were derived from a Worldview-2 image. Three window sizes (grains) were tested for analysis and computation of textural features, guided by the perception limits of different organisms. The modelled relationships between VHR-EO features and BS responses differed across scales, suggesting that landscape, patch and plot levels are respectively most appropriate when dealing with birds, plants and insects. This research demonstrates the potential of VHR-EO for biodiversity mapping and habitat modelling, and highlights the importance of identifying the appropriate scale of analysis for specific taxonomic groups of interest. Further, textural features are important in the modelling of functional group-specific indices which represent BS in high conservation value habitat types, and provide a more direct link to species interaction networks and ecosystem functioning, than provided by traditional taxonomic diversity indices.