Evaluating least-cost model predictions with empirical dispersal data: a case-study using radiotracking data of hedgehogs Eri



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Evaluating least-cost model predictions with empirical dispersal data: A case-study using radiotracking data of hedgehogs (Erinaceus europaeus) By: Driezen, Kassandra; Adriaensen, Frank; Rondinini, Carlo; Doncaster, C. Patrick; Matthysen, Erik. Ecological Modelling, Dec2007, Vol. 209 Issue 2-4, p314-322, 9p Abstract: Habitat fragmentation and habitat loss are widely recognized as major threats to biodiversity on a regional as well as on a global scale. To restrict its effects, ecological networks such as the trans-European network NATURA2000 are being developed based on the assumption that structural connections between habitat fragments lead to increased exchange through dispersal and a higher viability of (meta)populations. However, there is a great need for techniques that translate these networks and/or structural characteristics of landscapes into functional connectivity for specific organisms. Least-cost analysis has the capacities to fulfill these needs, but has never been validated against actual observations of dispersal paths. Here we present a method to validate the results of a least-cost analysis by comparing realized movement paths of hedgehogs in unfamiliar areas, obtained by radiotracking, with statistics on landscape-wide distribution of cost values. The degree of correspondence between empirical dispersal paths and the output of a least-cost analysis can be visualized and quantified, and least-cost scenarios can be statistically compared. We show that hedgehogs moved along paths with significantly lower cost values than the average landscape, implying that they took better than random routes, but performance was relatively poor. We attribute this to the relatively generalistic habitat use of the model species and the rather homogeneous landscapes. We conclude that this approach can be useful for further validation of the least-cost model and allows a direct comparison of model performance among different taxa and/or landscapes.
Assessing the conservation status of the tiger Panthera tigris at priority sites in Peninsular Malaysia. By: Lynam, Antony J.; Laidlaw, Ruth; Bennett, Elizabeth L.; Noordin, Wan Shaharuddin Wan; Elagupillay, Sivananthan. Oryx, Oct2007, Vol. 41 Issue 4, p454-462, 9p, 3 charts, 1 diagram Abstract: Wildlife managers require status and distribution information for informed decisions. Recognizing the tiger's globally threatened status and potential as an umbrella species for protection of forested landscapes, camera trap surveys for tigers and other large mammals have been conducted since 1997 in Peninsular Malaysia with the aim of assessing the population status of tigers in the Peninsula. Results from surveys at nine sites between December 1997 and December 1999 are reported here. Tigers were confirmed from six sites in the Main Range and Greater Taman Negara landscape, with multiple locations inside putative priority tiger areas. Although the data were collected 8 years ago, they are supplemented with more recent information, including tiger-human conflict investigations during 2000-2005 that indicate tiger persistence at these sites. Tiger density estimates were 0.51-1.95 tigers per 100 km2. With results from other surveys, this suggests a national population of up to several hundred tigers. A thorough survey, with sufficient resources, should be carried out in the future to derive a more reliable tiger population estimate for Malaysia. Key threats are habitat loss and fragmentation, hunting of prey, commercial trade in tiger parts, and harassment and displacement. Recommendations for the recovery of tigers in Peninsular Malaysia are provided.
Landscape genetics of Physalaemus cuvieri in Brazilian Cerrado: Correspondence between population structure and patterns of human occupation and habitat loss By: Telles, Mariana Pires de Campos; Diniz-Filho, José Alexandre Felizola; Bastos, Rogério Pereira; Soares, Thannya Nascimento; Guimarães, Lorena Dall‘Ara; Lima, Leôncio Pedrosa. Biological Conservation, Sep2007, Vol. 139 Issue 1/2, p37-46, 10p Abstract: It is now widely recognized that knowledge on population genetic structure is important to evaluate population viability and persistence or to establish conservation priorities. In this context, species that are locally abundant or widely distributed can be informative on how broad scale processes of habitat loss and fragmentation, as those caused by intensive human occupation, affect population genetic structure. In this paper, we analyzed population genetic structure of Physalaemus cuvieri (Amphibia: Leptodactylidae) in the core of the Cerrado biome, in the Goiás State, Central Brazil, using RAPD molecular markers. Local populations are genetically different according to RAPD markers, and an analysis of molecular variation (AMOVA) revealed a significant interpopulational variance component around 10%. However, these population differentiation patterns are not strongly structured in geographic space, and a Mantel spatial correlogram indicated only a slight significant spatial structure at short geographic distances. These patterns are expected by the ecological and life-history knowledge of the species, leading to a relatively low magnitude of population differentiation coupled with short distance spatial patterns. Moreover, even these weak patterns showed a signature of effects of human occupation and habitat loss on genetic differentiation at regional scale, with discontinuities to gene flow in two particular regions of the State with more intense habitat loss and older human settlement.
Terrain use by an expanding brown bear population in relation to age, recreational resorts and human settlements By: Nellemann, Christian; Støen, Ole-Gunnar; Kindberg, Jonas; Swenson, Jon E.; Vistnes, Ingunn; Ericsson, Göran; Katajisto, Jonna; Kaltenborn, Bjørn Petter; Martin, Jodie; Ordiz, Andrés. Biological Conservation, Aug2007, Vol. 138 Issue 1/2, p157-165, 9p Abstract: Brown bears (Ursus arctos) are threatened by habitat loss, habitat fragmentation by infrastructure and human settlements, and have been hunted to local extinction in large areas of their former range. We analyzed the habitat use during the non denning period of 106 radio-collared bears in an expanding bear population in Sweden in relation to resorts and towns, terrain ruggedness, sex and age of bears. Bear use increased substantially with increasing distance to towns and resorts for comparable habitat and terrain types, also for independent scat surveys using DNA-analyses. More than 74% of all female bear locations were in the 29% of the terrain classified as “rugged” and located >10km from any town or resort, whereas similar habitat closer to towns or resorts was avoided. Bears closer to larger settlements and resorts (<10km) were on average 27–51% younger than in areas beyond (mean 4.4±0.4 versus 8.9±0.8 years for males and 4.4±0.4 versus 6.0±0.2 years for females). Sub-adult bears (<4years) comprised up to 52% of all bear use within 10km from resorts and settlements, likely representing exploratory dispersing individuals. These areas, however, contained only 8% of the old males (>7years), the remaining 92% located beyond 10km from major resorts and settlements. Recreational resorts are developing rapidly, typically near national parks, and may thus limit expansion or fragment existing bear habitats. Together with active conservation, safeguarding undeveloped corridors of forest and rugged terrain may be important for successful recolonization of the brown bear into its original range

Human and domestic animal populations as a potential threat to wild carnivore conservation in a fragmented landscape from the Eastern Brazilian Amazon By: Whiteman, Christina Wippich; Matushima, Eliana Reiko; Cavalcanti Confalonieri, Ulisses Eugênio; Palha, Maria das Dores Correia; da Silva, Alanna do Socorro Lima; Monteiro, Vanessa Conceição. Biological Conservation, Aug2007, Vol. 138 Issue 1/2, p290-296, 7p Abstract: Hydroelectric projects are one of the well known factors responsible for habitat loss and fragmentation in the Amazon. The Tucuruí Lake Protected Area (Tucuruí Lake APA), in the state of Pará, Brazil, Eastern Brazilian Amazon, is under the influence of the Tucuruí dam. Zones of wildlife protection (ZWPs), where no human activities should be allowed, were created inside this protected area. However, human populations and their domestic animals still reside within the ZWPs. Domestic carnivores have been implicated in wild carnivore population declines, particularly in Africa, as a consequence of disease transmission, especially involving the canine distemper virus. This study examined the seroprevalence of antibodies to this pathogen in domestic dogs from the ZWPs and its immediate surroundings at the Tucuruí Lake Protected Area, and revealed 27% seropositivity. Wild carnivore species such as the jaguar (Panthera onca), puma (Puma concolor), ocelot (Leopardus pardalis), coati (Nasua nasua), among others, inhabit the ZWPs and information provided by the local community indicates their close contact with the human and domestic dog populations. Such evidence supports the concern that relates the presence of the domestic dogs to disease transmission and conservation risks for wild carnivores in the ZWPs of the Tucuruí Lake APA.
Landscape modification and habitat fragmentation: a synthesis. By: Fischer, Joern; Lindenmayer, David B.. Global Ecology & Biogeography, May2007, Vol. 16 Issue 3, p265-280, 16p, 3 charts, 5 diagrams Abstract: Landscape modification and habitat fragmentation are key drivers of global species loss. Their effects may be understood by focusing on: (1) individual species and the processes threatening them, and (2) human-perceived landscape patterns and their correlation with species and assemblages. Individual species may decline as a result of interacting exogenous and endogenous threats, including habitat loss, habitat degradation, habitat isolation, changes in the biology, behaviour, and interactions of species, as well as additional, stochastic threats. Human-perceived landscape patterns that are frequently correlated with species assemblages include the amount and structure of native vegetation, the prevalence of anthropogenic edges, the degree of landscape connectivity, and the structure and heterogeneity of modified areas. Extinction cascades are particularly likely to occur in landscapes with low native vegetation cover, low landscape connectivity, degraded native vegetation and intensive land use in modified areas, especially if keystone species or entire functional groups of species are lost. This review (1) demonstrates that species-oriented and pattern-oriented approaches to understanding the ecology of modified landscapes are highly complementary, (2) clarifies the links between a wide range of interconnected themes, and (3) provides clear and consistent terminology. Tangible research and management priorities are outlined that are likely to benefit the conservation of native species in modified landscapes around the world. [ABSTRACT FROM AUTHOR]; DOI: 10.1111/j.1466-8238
Not rare, but threatened: the endemic Madagascar flying fox Pteropus rufus in a fragmented landscape. By: Jenkins, Richard K. B.; Andriafidison, Daudet; Razafimanahaka, H. Julie; Rabearivelo, Andriamanana; Razafindrakoto, Noromampiandra; Ratsimandresy, Zo; Andrianandrasana, Rabe H.; Razafimahatratra, Emilienne; Racey, Paul A.. Oryx, Apr2007, Vol. 41 Issue 2, p263-271, 9p Abstract: The endemic Madagascar flying fox Pteropus rufus is threatened by habitat loss at roost sites and hunting for bushmeat. There is no conservation plan for this species, even though it is categorized on the IUCN Red List as Vulnerable and plays an important role as a seed disperser. In the Mangoro valley of central eastern Madagascar we monitored roost occupancy and abundance of P. rufus on 15 occasions at six sites over a 12-month period and conducted a detailed assessment of eight roosts during July 2004. There was considerable monthly variation in bat abundance and only two sites contained bats during every visit. Three sites were occupied only between September and March and may act as maternity or nursery roosts. Evidence of hunting was found at three roosts, and fire and forest clearance are ubiquitous threats. Two roosts were in Eucalyptus plantations and six were in small (2.2 - 28.7 ha) isolated fragments of degraded, mid elevation dense humid forest. All roosts were outside protected areas but were within 20 km of relatively intact forest. Faecal analysis revealed a diet of native forest tree species, cultivated fruits and Eucalyptus flowers. P. rufus in the Mangoro valley, and elsewhere in Madagascar, appears to survive in human-impacted environments by the inclusion of exotic plants in its diet and the ability to move between roosts. We provide conservation recommendations for P. rufus at both local and national levels. [ABSTRACT FROM AUTHOR]; DOI: 10.1017/S0030605307001883
Effect of Human Disturbance on Bee Communities in a Forested Ecosystem. By: WINFREE, RACHAEL; GRISWOLD, TERRY; KREMEN, CLAIRE. Conservation Biology, Feb2007, Vol. 21 Issue 1, p213-223, 11p, 3 charts, 6 graphs, 1bw Abstract (English): It is important for conservation biologists to understand how well species persist in human-dominated ecosystems because protected areas constitute a small fraction of the Earth's surface and because anthropogenic habitats may offer more opportunities for conservation than has been previously thought. We investigated how an important functional group, pollinators (bees; Hymenoptera: Apiformes), are affected by human land use at the landscape and local scales in southern New Jersey (U.S.A.). We established 40 sites that differed in surrounding landscape cover or local habitat type and collected 2551 bees of 130 species. The natural habitat in this ecosystem is a forested, ericaceous heath. Bee abundance and species richness within forest habitat decreased, not increased, with increasing forest cover in the surrounding landscape. Similarly, bee abundance was greater in agricultural fields and suburban and urban developments than in extensive forests, and the same trend was found for species richness. Particular species groups that might be expected to show greater sensitivity to habitat loss, such as floral specialists and bees of small or large body size, did not show strong positive associations with forest habitat. Nevertheless, 18 of the 130 bee species studied were positively associated with extensive forest. One of these species is a narrow endemic that was last seen in 1939. Our results suggest that at least in this system, moderate anthropogenic land use may be compatible with the conservation of many, but not all, bee species. [ABSTRACT FROM AUTHOR]; DOI: 10.1111/j.1523-1739.2006.00574.x; (AN 23922664)
The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: A case study of koalas in Queensland, Australia. By: McAlpine, Clive A.; Rhodes, Jonathan R.; Callaghan, John G.; Bowen, Michiala E.; Lunney, Daniel; Mitchell, David L.; Pullar, David V.; Possingham, Hugh P.. Biological Conservation, Oct2006, Vol. 132 Issue 2, p153-165, 13p Abstract: Abstract: The loss and fragmentation of forest habitats by human land use are recognised as important factors influencing the decline of forest-dependent fauna. Mammal species that are dependent upon forest habitats are particularly sensitive to habitat loss and fragmentation because they have highly specific habitat requirements, and in many cases have limited ability to move through and utilise the land use matrix. We addressed this problem using a case study of the koala (Phascolarctos cinereus) surveyed in a fragmented rural–urban landscape in southeast Queensland, Australia. We applied a logistic modelling and hierarchical partitioning analysis to determine the importance of forest area and its configuration relative to site (local) and patch-level habitat variables. After taking into account spatial autocorrelation and the year of survey, we found koala occurrence increased with the area of all forest habitats, habitat patch size and the proportion of primary Eucalyptus tree species; and decreased with mean nearest neighbour distance between forest patches, the density of forest patches, and the density of sealed roads. The difference between the effect of habitat area and configuration was not as strong as theory predicts, with the configuration of remnant forest becoming increasingly important as the area of forest habitat declines. We conclude that the area of forest, its configuration across the landscape, as well as the land use matrix, are important determinants of koala occurrence, and that habitat configuration should not be overlooked in the conservation of forest-dependent mammals, such as the koala. We highlight the implications of these findings for koala conservation.

Sacred Cows and Sympathetic Squirrels: The Importance of Biological Diversity to Human Health. By: Dobson, Andy; Cattadori, Isabella; Holt, Robert D.; Ostfeld, Richard S.; Keesing, Felicia; Krichbaum, Kristle; Rohr, Jason R.; Perkins, Sarah E.; Hudson, Peter J.. PLoS Medicine, Jun2006, Vol. 3 Issue 5, pe231-0718, 5p, 3c; Abstract: The article discusses the importance of biological diversity to human health. A description of how disease risk is influenced by biological diversity is presented. The role of host species in reducing the transmission of virulent zoonotic pathogens to people is explained. Human processes that contribute to the loss of biological diversity are cited. They include habitat loss and fragmentation, and overexploitation of populations for food or other economic uses.; DOI: 10.1371/journal.pmed.0030231; (AN 23454842)


The roles of landscape context, niche breadth, and range boundaries in predicting species responses to habitat alteration. By: Swihart, Robert K.; Lusk, Jeffrey J.; Duchamp, Joseph E.; Rizkalla, Carol E.; Moore, Jeffrey E.. Diversity & Distributions, May2006, Vol. 12 Issue 3, p277-287, 11p Abstract: Extant species in human-dominated landscapes differ in their sensitivity to habitat loss and fragmentation, although extinctions induced by environmental alteration reduce variation and result in a surviving subset of species with some degree of ‘resistance’. Here, we test the degree to which variable responses to habitat alteration are (1) essentially an inherent property of a taxon subject to constraints imposed by its geographical range, as suggested by Swihart et al. (2003), (2) a function of the landscape in which a species occurs, or (3) a function of spatial trends occurring on large scales. We used data collected on 33 vertebrate species during 2001–04 across the upper Wabash River basin, Indiana, in 35 square ‘landscapes’, each 23 km2 in size. Six species of forest rodent, six species of grassland rodents, seven species of bats, eight species of aquatic turtles, and six species of amphibians were sampled at 504, 212, 590, 228, and 625 patches, respectively. The fraction of patches of primary habitat (e.g. forests for tree squirrels, wetlands for aquatic turtles) occupied by a target species was used as a response variable. On a basin-wide scale, 47% of variation in proportional occupancy among species could be explained by taxon-specific variables; occupancy rates were related positively to niche breadth and negatively to the proximity of a geographical range boundary. After controlling for species effects, landscape-level occupancy rates varied significantly for 16 of 33 species, with variation partitioned among landscape variables alone (mean = 11% of variation), spatial trend variables alone (26%), and both variable sets jointly (8%). Among landscape variables, percentage forest cover positively affected occupancy rates of three bat species and a tree squirrel. Variation in occupancy rates among landscapes was consistent with large-scale spatial trends for 13 species...
Confounding factors in the detection of species responses to habitat fragmentation. By: Ewers, Robert M.; Didham, Raphael K.. Biological Reviews, Feb2006, Vol. 81 Issue 1, p117-142, 26p, 2 diagrams, 4 graphs Abstract: Habitat loss has pervasive and disruptive impacts on biodiversity in habitat remnants. The magnitude of the ecological impacts of habitat loss can be exacerbated by the spatial arrangement -- or fragmentation -- of remaining habitat. Fragmentation per se is a landscape-level phenomenon in which species that survive in habitat remnants are confronted with a modified environment of reduced area, increased isolation and novel ecological boundaries. The implications of this for individual organisms are many and varied, because species with differing life history strategies are differentially affected by habitat fragmentation. Here, we review the extensive literature on species responses to habitat fragmentation, and detail the numerous ways in which confounding factors have either masked the detection, or prevented the manifestation, of predicted fragmentation effects. Large numbers of empirical studies continue to document changes in species richness with decreasing habitat area, with positive, negative and no relationships regularly reported. The debate surrounding such widely contrasting results is beginning to be resolved by findings that the expected positive species-area relationship can be masked by matrix-derived spatial subsidies of resources to fragment-dwelling species and by the invasion of matrix-dwelling species into habitat edges. Significant advances have been made recently in our understanding of how species interactions are altered at habitat edges as a result of these changes. Interestingly, changes in biotic and abiotic parameters at edges also make ecological processes more variable than in habitat interiors. Individuals are more likely to encounter habitat edges in fragments with convoluted shapes, leading to increased turnover and variability in population size than in fragments that are compact in shape. Habitat isolation in both space and time disrupts species distribution patterns, with consequent effects on metapopulation dynamics and the...

Morphological consequences of range fragmentation and population decline on the endangered Iberian lynx ( Lynx pardinus). By: Pertoldi, C.; García-Perea, R.; Godoy, J. A.; Delibes, M.; Loeschcke, V.. Journal of Zoology, Jan2006, Vol. 268 Issue 1, p73-86, 14p, 4 charts, 2 diagrams Abstract: The Iberian lynx Lynx pardinus is one of the world's most endangered felids and is vulnerable to


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