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The risk of large carnivore mortality from anthropogenic sources is increased in areas where frequent human-carnivore encounters are high. Translocation is a potential tool for reducing these conflicts and re-establishing wild populations. Determining proper translocation sites for tigers is important for securing their future. In this research, we quantitatively evaluated the habitat suitability of a potential tiger translocation area on the Kampar Peninsula, a large peatland landscape in Sumatra. This landscape is essential for the conservation of the local tiger population, but its role as a tiger habitat has rarely been investigated. We conducted this research in a region with mosaicked land-use types covering an area of 7,045.89 km2. We applied species ecological niche factor analysis (ENFA) to model habitat suitability using species presence and ecogeographical variables as the bases. The model predicted that approximately 60% of the study area is tiger-suitable habitat with varying suitability levels. The tiger habitat characteristics in the study region are dissimilar to the global tiger habitat characteristics, and the high specialization value obtained indicates that tigers inhabit very narrow niches. Considering the low density of tigers in peatlands, we estimate that the carrying capacity of the whole Kampar landscape is approximately 13 tigers. Therefore, to conserve a viable tiger population, it is necessary to maintain connectivity between the Kampar peatlands and the Kerumutan landscape situated to the south of the Kampar Peninsula. [ABSTRACT FROM AUTHOR]

Species with different ecological niches will likely exhibit distinct responses to a changing environment. Differences in the magnitude of niche specialization may also indicate which species may be more vulnerable to environmental change, as many life‐history characteristics are known to affect climate change vulnerability. We characterized the niche space of three sympatric high‐elevation ground‐dwelling squirrels, yellow‐bellied marmot (Marmota flaviventer), Belding's ground squirrel (Urocitellus beldingi), and golden‐mantled ground squirrel (Callospermophilus lateralis), in the alpine and upper subalpine regions of the Sierra Nevada in California. We used 5879 observations of individual squirrels, collected from 4 years (2009–2012) of transect survey data, to quantify which ecogeographical variable types (climate, topography, or landcover) were most important in defining the niche of each species. We conducted Ecological Niche Factor Analysis to quantify the niche and generate indices of "marginality" (magnitude of selection) and "specialization" (narrowness of niche space). All three species demonstrated differential use of niche space when compared to the available niche space. Moreover, the relative importance of the variables shaping the niche differed among these species. For example, the presence of meadows was important in defining the niche for U. beldingi and M. flaviventer, but the presence of conifers was important to C. lateralis. Precipitation was important in defining the niche for all three species, positively so for U. beldingi, and negatively for the other two species. The niche breadth of these three species was also positively associated with geographic range size. Mammals in high‐elevation mountain systems often are perceived as vulnerable to climate shifts, but our results underscore the importance of also including non‐climate‐based factors in defining the niche. The overall magnitude of niche selection for all three species was driven by a combination of topographic, climatic, and landcover factors; thus, efforts to forecast areas where these species can persist in the future need to evaluate from more than just a climatic perspective. [ABSTRACT FROM AUTHOR]

Maps of potential biodiversity are prominent tools for regional conservation planning because they allow to quantify the diversity of species that potentially inhabit different habitats. These maps are constructed from modeling species ecological niches based on the association between the geographical localities where species were detected and the environmental variables at those localities. Previous researches addressed the development of MPB for administrative regions using regional species distributions data to modeling ecological niches, which may lead to flawed predictions on potential biodiversity. Our aim is to assess the consequences of failing to include all available records on full species distribution to develop MPB. As a study case, we produced two MPBs for an administrative region of Argentina using RSD and FSD data sets of 14 species of insects and performed Environmental Niche Factor Analysis to model their ecological niches. Our results evidenced that both MPB were not spatially congruent in their predictions on potential biodiversity, because the ecological niches represented by RSD and FSD data were different in their position and volume. We found that the MPB based on RSD data may underpredict the potential biodiversity of distinct habitats at the landscape level, and that the use of this map may underestimate areas with different conservation potential within an administrative region. These results suggest that the choice of the extent of geographic records used to construct the MPB strongly conditions the quality and credibility of these maps. [ABSTRACT FROM AUTHOR]

Background. Ecological niche and the habitat suitability modeling is becoming an increasingly important tool for finding the relationship of organisms with their habitat and refining data on their distribution. This work demonstrates some of the possibilities of such modeling for small mammals in stationary captures. Materials and methods. The work was carried out in the Central Forest Nature Reserve. The data from the captures of bank and red voles on the trap line for 2010–2014 were taken as the presence points, and 9 environmental variables were used as predictors. The modeling was carried out using a comprehensive approach, within the framework of which ecological niches of voles were modeled using ecological niche factor analysis, as well as habitat suitability maps using it and analyses by Mahalanobis distances. Results. The bank vole showed a low marginality index (0,56) and a relatively high tolerance index (0,68). The environmental conditions used by the species were slightly different from the average available conditions. Its suitable habitats were associated with relief elevations and watershed surfaces. The red vole had a high marginality index (1,39) and a low tolerance index (0,37). It is confined to a narrow range of preferred habitats: boreal spruce forests on elevated watersheds. Habitats suitable for voles are segregated, but not completely, showing partial overlap in the area of boreal spruce forests at elevations. Schoener's D-index value of niche overlap was 0.79. Conclusions. The ecological niches of the two forest vole species differed, which is associated with the peculiarities of habitat confinement. A significant overlap of areas of suitable habitats of the two species may be associated with incomplete mapping of the ecological relationships of the bank vole due to the insufficient representativeness of the trap line.

Modeling the distribution patterns of species is a generally efficient tool to assess their ecological characteristics. In this study, we compared ecological niche factor analysis (ENFA) and maximum entropy (Maxent) techniques to predict the most suitable distribution range of Rana macrocnemis. The Maxent model predicted potential suitable habitats for R. macrocnemis with high success rates (AUC Training data = 0.877 ± 0.039). According to the map constructed, three important variables had high contribution to species presence: temperature (50.4%), land cover (24.6%) and elevation (14.4%) variables. The ENFA results were relatively similar to Maxent jackknife analysis. The results implied that R. macrocnemis prefers grassland and needle leaf deciduous forest with high elevations, and low temperature. [ABSTRACT FROM AUTHOR]

In several European estuaries, the introduced Manila clam ( Ruditapes philippinarum ) has become a widespread and predominating species supplanting the native carpet shell clam ( Ruditapes decussatus ) whereas in other estuaries such as the Bay of Santander (Gulf of Biscay) this pattern has not been detected. Using this estuary as a case study, the potential coexistence/predominance patterns between these two species were explored with the objective of providing insight into the capacity of expansion of R. philippinarum . Firstly, the Ecological Niche Factor Analysis (ENFA) was applied to determine the niches of both species, using seven contemporary environmental variables, i.e. salinity, water depth, current velocity, and sediment sand, gravel, silt and organic matter content. Secondly, ENFA-derived habitat-suitability (HS) maps were simultaneously treated, using geospatial techniques and following HS index-based criteria, to determine the potential distribution patterns. Both species models performed well according to the cross-validation evaluation method. The environmental variables that most determined the presence of both clams were depth, current velocity and salinity. ENFA factors showed that R. philippinarum habitat differs more from the mean environmental conditions over the estuary (i.e. higher marginality) and has less narrow requirements (i.e. lower specialization). R. philippinarum dominated areas, determined by relatively lower current velocities and percentages of sand, higher organic matter contents and slightly shallower depths, were very reduced (i.e. 2.0% of the bay surface) compared to coexistence (47%) and R. decussatus predominance areas (7.4%). These results suggest that HS may regulate the expansion of R. philippinarum . ENFA, together with geospatial analysis of HS index, seems to be a valuable approach to explore the expansion potential of estuarine invasive or introduced species and thus support conservation decisions regarding native species. [ABSTRACT FROM AUTHOR]

Management actions are essential for mitigating the potentially harmful changes in biodiversity, ecosystem function and crop/forest productivity caused by invasive species. Species distribution models, if reliable, could be used to design effective management strategies. Although several modelling methods well suited for studying invasive species have been developed for presence-only data, often the size of available data sets for modelling is small and results are not validated with test samples. Moreover, the impact of such methods in practical applications has been overlooked. Here, we evaluated the reliability of the modelling approach based on ecological-niche factor analysis ( ENFA) implemented in Biomapper software when applied to environmental weed data in the Azores. Presence-only data sets of two top invasive woody species ( Pittosporum undulatum and Acacia melanoxylon) were used. The continuous Boyce curve was used for validation, calculated either in Biomapper (cross-validation) or based on test samples. The species' most habitable areas that should be regarded as management targets were thus estimated from modelling and validation. By imposing size restrictions on the presence-only data sets used in modelling and validation, other habitable areas were defined and compared. The ENFA proved to be a suitable method for modelling environmental weed distributions, regardless of the presence-only dataset size. Moreover, the cross-validation of Biomapper was reliable, although its results should be interpreted with caution as they could potentially lead to statistically different management target areas. [ABSTRACT FROM AUTHOR]

Aim Small range size often increases a species' susceptibility to decline. A narrow ecological niche is one factor that may cause species to inhabit a small range. We investigated whether specialized niches have made South African amphibians more vulnerable to range contractions. Location South Africa. Methods The South African Frog Atlas Project is a comprehensive dataset that combines a recent biological survey with historical species distribution data. It provided an opportunity to quantitatively compare range sizes, niche breadth and range size changes for amphibian species. An ecological niche factor analysis supplied comparative measures of climate and habitat niche breadth for each species. Niche breadth was related to range size changes using linear regressions. Ranges of species with narrow habitat niches were spatially compared to areas of high land transformation. Results Small range size was a significant predictor of range contractions for South African amphibians ( R2 = 0.35). Furthermore, species with narrow habitat ( R2 = 0.25) and climate ( R2 = 0.21) niches had experienced more severe range contractions than species with broader niches. Among only endemic species, climate specialization ( R2 = 0.27) became a better predictor of range size change than habitat specialization ( R2 = 0.21). Habitat specialists were concentrated within two areas of endemism that also had higher than average ( P < 0.0001) levels of land transformation. Main conclusions Small range size increased species' likelihood of experiencing range contractions. Narrow niche breadth was also a significant predictor of range contractions, indicating that specialization may contribute to higher decline risk in small-range species. The role of climate specialization in predicting range contractions among endemics emphasizes the potential impacts of climate change. The spatial synchrony of contracting habitat specialists in highly transformed areas of endemism suggests that conservation efforts should target specialist species and the ecosystems where many such species occur. [ABSTRACT FROM AUTHOR]

Abstract: Invasive alien species are considered to be one of the most important causes of extinction and decline of wild native species. The raccoon (Procyon lotor) is native to North and Central America but at present it also occurs in several European and Asian countries. In 1991, the raccoon was recorded for the first time in Iran from Lavandevil Wildlife Refuge. In order to examine how a variation in the extent of the study area influences habitat selection of the raccoon, we ran models at two different scales at Lavandevil Wildlife Refuge and the Gilan Province. We used the Ecological Niche Factor Analysis (ENFA) to describe the invasive raccoons' realized niche and to identify areas exposed to the invasion of the raccoon in northern Iran. Our results showed that the spatial distribution of the raccoon is heavily influenced by natural variables, landscape variables, and human-related variables at Lavandevil Wildlife Refuge scale and topography and vegetation variables at Gilan Province scale. This prediction indicates that the raccoon has a potential to become one of the most numerous mammals in northern Iran. [Copyright &y& Elsevier]

The Kashmir markhor, Capra falconeri cashmiriensis, is classified as endangered throughout its range because of habitat loss, unsustainable hunting and competition with domestic livestock. We investigated environmental factors influencing species distribution in Chitral Gol National Park (CGNP) based on the ‘presence-only’ dataset and predicted the potential distribution of markhor in order to compute a habitat suitability (HS) map using ecological niche factor analysis (ENFA). Kashmir markhor presence-only data was recorded for a period of four years during 2003–2007 from 487 point locations in summer, spring and winter. The geographical position of animals and the related topographic and habitat variables were used to accurately assess species occurrence within the study area and to predict its distribution. ENFA is used to describe distribution patterns and to identify key variables influencing the ecological niche of markhor. The ENFA model revealed that markhor occurred at a mean elevation of 2818 m with a mean slope of 33.4°. The species requirements seem different from the average habitat conditions available in the study area. Whereas the specialisation factor indicated some specific habitat requirements of markhor, it was found that they still occupied a wider ecological niche. The model suggested that markhor avoid higher elevations but showed a strong relationship with comparatively steep slopes. ENFA computed 25% of the area of CGNP under suitable and optimal conditions for the long-term existence of Kashmir markhor in CGNP. ENFA computed a HS map for markhor showing its widespread distribution within the study area. Steep slopes and a lower to medium elevation range were mostly preferred by markhor. [ABSTRACT FROM AUTHOR]

Jajroud Protected Area Complex is one of the main habitats of Alborz Red Sheep ( Ovis gmelini × O. vignei) in Iran. Being close to Tehran, this habitat has been reduced and fragmented due to the human constructions. This study was designed with the aim of identifying the summer and fall habitat patches and the suitability of the matrix by means of Ecological Niche Factor Analysis ( ENFA). Cost-distance function was then used to calculate the cost of moving among the patches and the corridors with the least cost was identified using Least-cost path analysis. Results showed that, in both seasons, the species inhabits a narrow niche and is very sensitive to habitat changes. Overall, a suitable habitat for this species is at an elevation of more than 1535 m, with a lower average temperature than average of the habitat, with suitable escape terrain, and away from villages. Military areas, based on their specific use, can have different effects on the habitat suitability. This species selects corridors which are close to escape terrain, with a slope of about 15 percent and low slope fluctuation. [ABSTRACT FROM AUTHOR]

Aim Globally, species distribution patterns in the deep sea are poorly resolved, with spatial coverage being sparse for most taxa and true absence data missing. Increasing human impacts on deep-sea ecosystems mean that reaching a better understanding of such patterns is becoming more urgent. Cold-water stony corals (Order Scleractinia) form structurally complex habitats (dense thickets or reefs) that can support a diversity of other associated fauna. Despite their widely accepted ecological importance, records of scleractinian corals on seamounts are patchy and simply not available for most of the global ocean. The objective of this paper is to model the global distribution of suitable habitat for stony corals on seamounts. Location Seamounts worldwide. Methods We compiled a database containing all accessible records of scleractinian corals on seamounts. Two modelling approaches developed for presence-only data were used to predict global habitat suitability for seamount scleractinians: maximum entropy modelling (Maxent) and environmental niche factor analysis (ENFA). We generated habitat-suitability maps and used a cross-validation process with a threshold-independent metric to evaluate the performance of the models. Results Both models performed well in cross-validation, although the Maxent method consistently outperformed ENFA. Highly suitable habitat for seamount stony corals was predicted to occur at most modelled depths in the North Atlantic, and in a circumglobal strip in the Southern Hemisphere between 20° and 50° S and shallower than around 1500 m. Seamount summits in most other regions appeared much less likely to provide suitable habitat, except for small near-surface patches. The patterns of habitat suitability largely reflect current biogeographical knowledge. Environmental variables positively associated with high predicted habitat suitability included the aragonite saturation state, and oxygen saturation and concentration. By contrast, low levels of dissolved inorganic carbon, nitrate, phosphate and silicate were associated with high predicted suitability. High correlation among variables made assessing individual drivers difficult. Main conclusions Our models predict environmental conditions likely to play a role in determining large-scale scleractinian coral distributions on seamounts, and provide a baseline scenario on a global scale. These results present a first-order hypothesis that can be tested by further sampling. Given the high vulnerability of cold-water corals to human impacts, such predictions are crucial tools in developing worldwide conservation and management strategies for seamount ecosystems. [ABSTRACT FROM AUTHOR]

Understanding the basis of habitat choice having important implications for explaining the distribution of organisms, as well as helping to differentiate between habitats of different quality for effective management. In this study, the effects of sex, age and reproductive status on habitat use patterns of cheetahs Acinonyx jubatus in the Serengeti plains were explored using Ecological Niche Factor Analysis (ENFA). Our results showed that gender and territoriality did not affect patterns of habitat use. However, females tended to be more specialized when they were young than when they were older, displaying a more restricted ecological niche. Likewise, older females without cubs were more specialized than the same adult females with young cubs. This result did not hold for younger females. Altogether, the ENFA approach allowed us to (1) use the large amount of incidental sighting data collected over 12 years on cheetah spatial distribution; (2) identify the importance of reproductive status and age on the relationship between animals and their habitat; (3) further demonstrate that ENFA is applicable in a wide range of situations, including for exploring individual variation in niche definition. [ABSTRACT FROM AUTHOR]

We propose here some refinements of the ecological-niche factor analysis (ENFA) to describe precisely one organism’s habitat selection. The ENFA is based on the concept of the ecological niche, and provides a measure of the realised niche within the available space from the computation of two parameters, the marginality and the specialization. By measuring the departure of the ecological niche from the average available habitat, the marginality identifies the preference of the individual, population, or species for specific conditions of the environment among the whole set of possibilities. The specialization appears as a consequence of the narrowness of the niche on some environmental variables. The ENFA is a factorial analysis that extracts one axis of marginality and several axes of specialization. We present here the use of biplots (i.e., the projection of both the pixels of the map and the environmental variables in the subspace extracted by the ENFA) as a way to identify the key-variables for management, assessing which habitat features are of prime importance and should be preserved or reinforced. With the help of this tool, we are now able to describe much more precisely the habitat selection of the organism under focus. In our application to the lynx in the Vosges mountains, based on sightings as well as other indices of lynx presence, we thus underlined a strong avoidance of agricultural areas by the lynx. We also highlighted the relative indifference of the lynx to the proximity of artificial areas and at the opposite, the sensitivity to the proximity of highways. The ENFA provides a suitable way to measure habitat use/selection under a large range of ecological contexts and should be used to define precisely the ecological niche and therefore identify the characteristics searched for by the organism under study. [Copyright &y& Elsevier]

We studied the geographical distribution and habitat suitability of an introduced ungulate, the aoudad ( Ammotragus lervia), that is currently expanding its range in south-eastern Iberian Peninsula. We assessed the niche of the species using Ecological Niche Factor Analysis (ENFA) on (1) environmental variables (climate and habitat type), and (2) potential aoudad landscape avoidance and human disturbance variables. We compared both niche descriptions to study the impact of human interference on niche selection of the species. ENFA models were calibrated using data on the population expanded from the original release location, in Sierra Espuña mountains, and validated using data from another free-ranging population, originated independently in the Alicante province. The habitat suitability model for the purely environmental niche predicts a potential distribution along a SW–NE axis in the study area, following the Cordillera Sub-Bética mountain range, being constrained by low winter precipitation, high altitude, high terrain slope, and the presence of forest. In addition to these ecological traits, roads and landscape use restricted the environmental range potentially available for the species. Since the aoudad is a potential competitor of native ungulates and a threat to endemic flora, prospects for its potential dispersion might be of great conservation value. [ABSTRACT FROM AUTHOR]

The objective of the present research was to compare Ecological Niche Factor Analysis (ENFA) and Artificial Neural Networks (ANN) to determine the optimum threshold of plant species (Thymus kotschyanus Boiss and Hohen. and Dactylis glomerata L.) in rangelands of Ardabil province. Systematic random sampling of vegetation was performed, and an overall 111 sites were considered and divided into two groups, namely sites with plant species and sites without plant species. Five plots of one square meter were placed in each site. The size of the plots was based on the magnitude of one or double the average area of the most common plant species. Plots were positioned along a 40-m transect (from the bottom of the slope to high altitudes with a distance of 10 m between the plots). Soil sampling was done in a depth of 0–30 cm (selected based on the activity of root plant species). Maps of environmental factors were prepared in ArcGIS 10.4.1 software. The sensitivity and specificity were considered to specify the optimum threshold. The optimal threshold between plant species, determined by modeling methods, showed that the highest accuracy belonged to ENFA model in T. kotschyanus habitat (with optimum threshold = 0.62 and sensitivity = 0.58) and ANN model in D. glomerata habitat (with optimum threshold = 0.37 and sensitivity = 0.02) had the lowest accuracy. • Investigated application of modeling techniques in rangelands of Iran. • Investigated optimum threshold of plant species. • Impact of the most important environmental factors on the habitat of species Thymus kotschyanus Boiss and Hohen. and Dactylis glomerata L. [ABSTRACT FROM AUTHOR]

• The aim is to model the pheno-climatic conditions suitable for masting in beech. • We exploited the concept of ecological niche, by using SPEI and masting years. • We analyzed the relationship between climate and remotely sensed phenology. • Reproduction and growth in beech act as two different climate-dependent responses. Masting is a complex mechanism which is mainly driven by a combination of internal plant resources and climatic conditions. While the driving role of climate in masting is being intensively studied, the interplay among climate, seed production, vegetation growth and phenology still needs further investigation. The objectives of this study were to identify the climatic determinants of different levels of seed production and of NDVI-based vegetation growth and phenology in European beech, and to evaluate if exists a trade-off between these two plant processes. To answer these questions, we used a 25-year-long dataset of beech seed production. We exploited the concept of ecological niche assuming that a mast year can be modeled like a species with variable preferences for different resources, which are the underlying annual climatic conditions; we performed an Ecological Niche Factor Analysis (ENFA), a presence-only modeling tool conventionally used in zoology and botany, and used seasonal (spring, summer, autumn) Standardized Precipitation-Evaporation Index (SPEI) observations, considering the current year (y−0), and up to one (y−1) and two (y−2) years before the masting event. For analyzing the role of vegetation growth and phenology, we used seasonal Normalized Difference Vegetation Index (NDVI) values and associated NDVI-based phenological metrics derived from Landsat imagery. Results indicated the driving role of climate for masting, especially in VHSP years. A moist summer and dry spring at y−2 and a dry summer at y−1 represented the main driving climatic conditions for masting; while a moist spring during the observation year represented the key condition for triggering higher intensities of seed production. Summer NDVI at y−0 and y−1 represented the variables discriminating best between masting and non-masting years and resulted as driven by opposite summer climatic conditions than seed production, thus indicating a trade-off between seed production and vegetation phenology. We concluded that reproduction and vegetation growth act as two different climate-dependent plant responses in beech, in a way that certain conditions through the years promote mast seeding and the opposite conditions favor vegetation growth. The understanding of climate-growth-masting relationships represents indispensable knowledge for providing a holistic view of masting mechanisms and developing adaptive forest management strategies in this species. [ABSTRACT FROM AUTHOR]

Background: Biting aquatic insects belonging to the order Hemiptera have been suggested as potential vectors of Mycobacterium ulcerans in endemic areas for Buruli ulcer (BU). If this is the case, these insects would be expected to co-exist with M. ulcerans in the same geographical areas. Here, we studied the geographical distribution of six aquatic Hemiptera families that are thought to be vectors of M. ulcerans and explored their potential geographical overlapping with communities reporting BU cases in endemic countries. Methods: We have developed ensemble ecological models of predicted distribution for six families of the Hemiptera (Naucoridae, Belostomatidae, Notonectidae, Nepidae, Corixidae and Gerridae) applying a robust modelling framework over a collection of recorded presences and a suite of environmental and topographical factors. Ecological niche factor analysis (ENFA) was first used to identify factors that best described the ecological niches for each hemipteran family. Finally, we explored the potential geographical co-occurrence of these insects and BU in two endemic countries, Cameroon and Ghana. Results: Species of the families Naucoridae and Belostomatidae, according to our models, are widely distributed across Africa, although absent from drier and hotter areas. The other two families of biting Hemiptera, the Notonectidae and Nepidae, would have a more restricted distribution, being more predominant in western and southern Africa. All these four families of biting water bugs are widely distributed across coastal areas of West Africa. They would thrive in areas where annual mean temperature varies between 15–22 °C, with moderate annual precipitation (i.e. 350–1000 mm/annual) and near to water courses. Species of all hemipteran families show preference for human-made environments such as agricultural landscapes and urbanized areas. Finally, our analysis suggests that M. ulcerans and species of these aquatic insects might coexist in the same ecological niches, although there would be variation in species diversity between BU endemic areas. Conclusions: Our findings predict the geographical co-existence of some species of aquatic hemipteran families and BU. Considering the existing biological evidence that points to some of these aquatic insects as potential phoretic vectors of M. ulcerans, its presence in BU endemic areas should be considered a risk factor. The ecological models here presented may be helpful to inform future environmental based models intended to delineate the potential geographical distribution of BU in the African region. [ABSTRACT FROM AUTHOR]