High-use movement pathways and habitat selection by ungulates

The cumulative movements of large mammals are expressed in many areas as semi-permanent wildlife trails. The mapping of semi-permanent trail networks offers a direct approach to assess habitat selection of high-use movement routes at relatively fine spatial scales across a landscape. Here we examine an ungulate trail network in north-central Utah created and maintained by the repeated movements of mule deer (Odocoileus hemionus) and elk (Cervus elaphus). In a resource selection analysis using multivariable spatial regression analysis, we show that at a spatial scale of 70 m open and low cover and distance to water are important predictors of movement pathway density. We also demonstrate at a scale of 10 m that elk and deer movement pathways are less steep than adjacent terrain. The mapping of trail networks should be a particularly useful technique for examining functional connectivity among resource patches across a landscape and identifying important high-use movement routes.     

Density-dependent habitat selection and partitioning between two sympatric ungulates

Theory on density-dependent habitat selection predicts that as population density of a species increases, use of higher quality (primary) habitat by individuals declines while use of lower quality (secondary) habitat rises. Habitat partitioning is often considered the primary mechanism for coexistence between similar species, but how this process evolves with changes in population density remains to be empirically tested for free-ranging ungulates. We used resource-selection functions to quantify density effects on landscape-scale habitat selection of two sympatric species of ungulates [moose (Alces alces) and elk (Cervus canadensis manitobensis)] in Riding Mountain National Park, Manitoba, Canada (2000–2011). The density of elk was actively reduced from 1.2 to 0.4 elk km^?2 through increased hunting effort during the period of study, while moose density decreased without additional human influence from 1.6–0.7 moose km^?2. Patterns of habitat selection during winter by both species changed in accordance to expectations from density-dependent habitat-selection theory. At low intraspecific density, moose and elk did not partition habitat, as both species selected strongly for mixed forest (primary habitat providing both food and cover), but did so in different areas segregated across an elevational gradient. As intraspecific density increased, selection for primary habitat by both species decreased, while selection for secondary, lower quality habitat such as agricultural fields (for elk) and built-up areas (for moose) increased. We show that habitat-selection strategies during winter for moose and elk, and subsequent effects on habitat partitioning, depend heavily on the position in state space (density) of both species.     

A model for habitat selection and species distribution derived from central place foraging theory

We have developed a habitat selection model based on central place foraging theory. An individual’s decision to include a patch in its habitat depends on the marginal fitness contribution of that patch, which is characterized by its quality and distance to the central place. The essence of the model we have developed is a fitness isocline which is a function of patch quality and travel time to the patch. It has two parameters: the maximum travel distance to a patch of infinite quality and a coefficient that appropriately scales quality by travel time. Patches falling below the isocline will have positive marginal fitness values and should be included in the habitat. The maximum travel distance depends on the availability and quality of patches, as well as on the forager’s life history, whereas the scaling parameter mostly depends on life history properties. Using the model, we derived a landscape quality metric (which can be thought of as a connectivity measure) that sums the values of available habitat in the landscape around a central place. We then fitted the two parameters to foraging data on breeding white storks (Ciconia ciconia) and estimated landscape quality, which correlated strongly with reproductive success. Landscape quality was then calculated for a larger region where re-introduction of the species is currently going on in order to demonstrate how this model can also be regarded as a species distribution model. In conclusion, we have built a general habitat selection model for central place foragers and a novel way of estimating landscape quality based on a behaviorally scaled connectivity metric.     

Evaluating habitat selection models to predict critical habitat for mountain goats in northwest British Columbia

Anthropogenic activity imposes increasing pressure on wildlife populations globally; these pressures can affect habitat suitability and function, modify wildlife space use, and influence population viability. Native mountain goat (Oreamnos americanus) populations can be negatively affected by anthropogenic disturbance and modify their space use in response to land development and recreational activity. From 2018 to 2020, we studied space use of mountain goats northeast of Smithers, British Columbia, Canada, an area that is subject to increasing anthropogenic development and yearlong recreational activities. We aimed to generate models that would improve our ability to identify habitat for mountain goats relative to existing survey data and established ungulate winter ranges. Using resource selection function (RSF) analyses generated from global positioning system (GPS) collar data, we identified influential habitat covariates and compared these covariates and RSF values to existing habitat models. Additionally, we compared the extent to which our models were congruent with existing resource selection probability functions, were congruent with aerial survey data, and overlapped existing ungulate winter ranges previously derived from predictive models inside and outside of the study area. Overall, our models noted higher RSF values among GPS data relative to aerial survey data for winter months, while results for summer habitats were comparable. In extending our RSFs outside of the study area and evaluating the overlap with ungulate winter ranges in adjacent areas, values were similar, albeit lower, as is expected given that the models were developed elsewhere. Ultimately, these models, combined with existing methods, improve the accuracy and reliability of identified, important areas of habitat for mountain goats. We recommend that the RSF models generated here be used in conjunction with aerial survey data and existing methods to delineate ungulate winter ranges for mountain goats in similar eco-regions in British Columbia. The models developed here support existing methods that have been used to delineate or validate ungulate winter ranges for mountain goats in British Columbia and help facilitate mitigation measures to support the continued use of important winter habitat and significant landscape features that play a role in ensuring population viability and resilience through time.     

Spatial scale and the cost of density-dependent habitat selection

Summary Habitat selection costs depend upon the scale of habitat. At the fine-grained microhabitat scale, cost is linked to optimal foraging, and habitat selection should be abandoned even though fitness is greater in one microhabitat than in another. At the coarse-grained macrohabitat scale, cost is linked to emigration, and habitat selection should often be maintained even though fitness may be less in the preferred macrohabitat than in others. Macrohabitat selection cost is easily incorporated into habitat selection theory and can be tested by linear regression techniques on isodars (lines of every point at which the fitness of individuals in one habitat equals that of individuals in another). The results of one recent survey of white-footed mice living in different macrohabitats are consistent with the predictions of emigration cost.     

Determining habitat quality for species that demonstrate dynamic habitat selection

Determining habitat quality for wildlife populations requires relating a species' habitat to its survival and reproduction. Within a season, species occurrence and density can be disconnected from measures of habitat quality when resources are highly seasonal, unpredictable over time, and patchy. Here we establish an explicit link among dynamic selection of changing resources, spatio‐temporal species distributions, and fitness for predictive abundance and occurrence models that are used for short‐term water management and long‐term restoration planning. We used the wading bird distribution and evaluation models (WADEM) that estimate (1) daily changes in selection across resource gradients, (2) landscape abundance of flocks and individuals, (3) conspecific foraging aggregation, and (4) resource unit occurrence (at fixed 400 m cells) to quantify habitat quality and its consequences on reproduction for wetland indicator species. We linked maximum annual numbers of nests detected across the study area and nesting success of Great Egrets (Ardea alba), White Ibises (Eudocimus albus), and Wood Storks (Mycteria americana) over a 20‐year period to estimated daily dynamics of food resources produced by WADEM over a 7490 km² area. For all species, increases in predicted species abundance in March and high abundance in April were strongly linked to breeding responses. Great Egret nesting effort and success were higher when birds also showed greater conspecific foraging aggregation. Synthesis and applications: This study provides the first empirical evidence that dynamic habitat selection processes and distributions of wading birds over environmental gradients are linked with reproductive measures over periods of decades. Further, predictor variables at a variety of temporal (daily‐multiannual) resolutions and spatial (400 m to regional) scales effectively explained variation in ecological processes that change habitat quality. The process used here allows managers to develop short‐ and long‐term conservation strategies that (1) consider flexible behavioral patterns and (2) are robust to environmental variation over time.     

Spatial heterogeneity in habitat selection: Nest site selection by greater prairie-chickens

Ecological relationships of animals and their environments are known to vary spatially and temporally across scales. However, common approaches for evaluating resource selection by animals assume that the processes of habitat selection are stationary across space. The assumption that habitat selection is spatially homogeneous may lead to biased inference and ineffective management. We present the first application of geographically weighted logistic regression to habitat selection by a wildlife species. As a case study, we examined nest site selection by greater prairie-chickens at 3 sites with different ecological conditions in Kansas to assess whether the relative importance of habitat features varied across space. We found that 1) nest sites were associated with habitat conditions at multiple spatial scales, 2) habitat associations across spatial scales were correlated, and 3) the influence of habitat conditions on nest site selection was spatially explicit. Post hoc analyses revealed that much of the spatial variability in habitat selection processes was explained at a regional scale. Moreover, habitat features at local spatial scales were more strongly associated with nest site selection in unfragmented grasslands managed intensively for cattle production than they were in fragmented grasslands within a matrix of farmland. Female prairie-chickens exhibited spatial variability in nest site selection at multiple spatial scales, suggesting plasticity in habitat selection behavior. Our results highlight the importance of accounting for spatial heterogeneity when evaluating the ecological effects of habitat components. © 2013 The Wildlife Society.     

Variation in habitat use of coexisting rodent species in a tropical dry deciduous forest

Use of habitat is a critical component related to structure of small-mammal communities, with partitioning occurring primarily along dimensions of microhabitat, although use of microhabitat often does not explain fully use at a macrohabitat level. Through grid studies of small mammals in coastal Colima, Mexico (during January 2003–2005), we appraised influence of available habitat, species richness, abundance, and cumulative abundance of other small mammals on variation in habitat used by species. We evaluated 14 habitat variables (reflecting ground cover, slope, canopy, and vegetation density on vertical and horizontal axes) and developed a composite variable (principal component 1) reflecting general openness of habitat through which we addressed habitat use. For the four most common mammalian species (Sigmodon mascotensis, Heteromys pictus, Baiomys musculus, and Oryzomys couesi), two measures of variation in habitat used were employed to estimate niche breadth, one of which assessed variation in habitat use relative to variation present on a grid. Sigmodon mascotensis and B. musculus preferred areas that were more open, and H. pictus and O. couesi occupied less-open areas; breadth of habitat use did not differ interspecifically. Habitat use was more variable on grids with more variability in habitat, although not greater than chance expectations. Findings do not lend support to the resource-breadth hypothesis as an explanation for population densities of species at a local level or the habitat-heterogeneity hypothesis as a predictor of species richness. Variation in habitat used by S. mascotensis did not proportionally increase when diverse habitat was available but was greater when the species was more abundant. For H. pictus, when cumulative abundance of other small mammals was greater, breadth of habitat used was greater. Intraspecific density-dependent habitat selection may result in S. mascotensis selecting a greater variety of habitats, while greater interspecific abundance is related to a greater range in use of habitats by H. pictus. Baiomys musculus used a higher proportion of habitat relative to that available when more species were present on a grid. Variation in habitat used by O. couesi was unrelated to any factor examined. Overall, the four species responded in notably different ways with respect to availability of habitat, abundance, and presence of other species.     

Spatial and host-plant partitioning between coexisting Bemisia tabaci cryptic species in Tunisia

The whitefly Bemisia tabaci is a species complex including at least 24 morphologically indistinguishable species among which the Mediterranean (Med) and Middle East-Asia Minor I (MEAMI) species containing the biotypes commonly known as Q and B, respectively. These B and Q biotypes (hereafter referred to as MEAMI and Med species) are the most invasive agricultural pests of the B. tabaci complex worldwide. The spread of MEAMI and more recently of Med species into regions already invaded by other B. tabaci populations has been frequently seen to lead to their displacement by Med species. In Tunisia, in contrast to usual observations in the Mediterranean basin, Med and MEAMI species have been seen to co-occur in the main crop producing regions. Based on fine population genetics and field spatial distribution analyses, we found that the co-existence of these two interacting species was based on habitat partitioning including spatial and host-plant partitioning. Although they co-occurred at larger spatial scales, they excluded one another at sample scale. We observed neither spatial overlapping nor hybridization between MEAMI and Med B. tabaci. Vegetable crops were the main hosts for MEAMI specimens while 99.1% of the B. tabaci collected on the ornamental, Lantana camara, were Med specimens. Different patterns of genetic diversity were observed between the two species, as well as among Med specimens sampled on the ornamental versus vegetables, with the highest genetic diversity found in Med B. tabaci sampled on L. camara. These findings lead us to focus our discussion on the role played by lantana, human pressure, and competition, in the spatial and genetic patterns observed in the whitefly B. tabaci.     

Reconciling social interaction with habitat selection in territorial species

The concept of habitat selection as the primary force in clustered distributions has been challenged by behavioral studies of conspecific attraction. This has lead to two conflicting explanations for settlement behavior, which we have integrated into one model. This model creates a range of fitness outcomes for different settlement strategies, encompassing the four combinations of positive and negative effects of the habitat selection and social interaction. It expands the ideal free distribution models (negative intra-specific interactions and positive habitat selection), to consider alternative situations where (1) beneficial social interaction increases fitness for clustered pairs in poor quality habitat, (2) neither habitat selection nor conspecific attraction can improve fitness, and (3) where both are beneficial and do not interfere with each other. The model does this by establishing an intrinsic fitness, where the effects of both habitat selection (h) and conspecific attractions (c) are neutral (h = c = 1) and do not influence settlement. Clustered distributions occur when h · c > 1 because the fitness in clusters is greater than intrinsic fitness. Dispersed distributions occur when h · c < 1 and fitness is lower than the intrinsic. The benefit of the model is that it allows conspecific attraction to be considered a positive force in fitness without rejecting the proven concept of ideal free distribution.     

华北山地典型天然次生林群落的树种空间分布格局及其关联性

关帝山华北落叶松、云杉、杨桦天然次生林植被类型是华北高海拔地带代表性的森林类型。以该地区上述3种典型的天然次生林群落为例,运用点格局分析中的单变量O-ring统计方法,分析各群落主要树种的种群空间分布格局;用双变量O-ring统计方法,分析各群落中树种间的空间关联性;并对同一树种在不同森林群落类型中种群空间分布格局和种间关联性的变化进行比较,以探讨华北山地次生林群落空间格局形成和种群维持与动态机制。研究结果表明,(1)各种群在相对小的尺度上聚集分布特征明显,随尺度增加树木种群的聚集性减弱并逐渐表现出随机分布的格局特征;(2)同一树种在不同森林群落类型中空间分布格局差异很大。红桦、白桦和山杨在阔叶林中呈明显的小尺度聚集分布格局,而在针叶林群落呈随机分布。在阔叶次生林中混生的小龄级华北落叶松呈现聚集性空间分布格局。在华北落叶松为优势树种的针叶林中,大龄级的华北落叶松表现出小尺度上均匀分布和较大尺度上随机分布的格局特征;(3)各群落中树种间的空间关联性主要表现在小尺度范围,随尺度加大空间关联性逐渐不明显;(4)在阔叶树占优势的次生林,小龄级华北落叶松与桦木的分布有较明显的空间正关联性,而在华北落叶松为优势树种的针叶林,桦与华北落叶松并未表现明显的空间关联性。种群分布格局和种群间的空间关联性随群落结构、空间尺度和龄级结构不同而有较大变化。     

Experiments on habitat selection in voles: Implications for the inverse distribution of two common European species

Summary Several pairs of species of microtine rodents show inverse distributions or abundance. Here I determine if the inverse abundance relationship of the bank vole Clethrionomys glareolus (a forest species) and the field vole Microtus agrestis (an open field species) could be explained by habitat selection. Habitat selection was examined by choice experiments with combinations of soil and vegetation types, and with separate habitat factors. The effects of early experience and social behaviour were also studied, e.g. in a large outdoor enclosure. M. agrestis showed a stronger dependence on shelter (e.g. easily excavated soil or thick grassy vegetation) than C. glareolus, while the presence of preferred food did not affect habitat selection for either species. In both species, laboratory-bred specimens showed considerably fewer preferences. Habitat selection in subadult C. glareolus was influenced by social clumping, while territorial behaviour made more even distributions in M. agrestis.The less rigid habitat selection and weaker territorial behaviour observed in the forest species (Clethrionomys) compared with a species from temporary habitats (Microtus) is not consistent with present concepts of r- and K-selection.     

Testing habitat copying in breeding habitat selection in a species adapted to variable environments

The habitat copying hypothesis states that animals use the reproductive performance of conspecifics to evaluate habitat quality and choose their future breeding site. We used data from Audouin's Gull Larus audouinii (1992–2003), a species adapted to unpredictable environments, to analyse subcolony (as patch) choice within a colony (small spatial scale). We also assessed the suitability of alternative hypotheses to the habitat copying hypothesis. The probability of subcolonies being reoccupied annually increased with their size (as number of nests), which suggests the existence of group adherence effects. Subcolony growth rate was related to its average reproductive success (or patch reproductive success) in the previous year: the higher the reproductive success in a colony, the higher the probability of growth the following year. However, this last result was obtained without considering the effect of colony size on the response variable because colony size is related to it. Therefore, results suggest at the population level that in this system habitat copying might either be one of the strategies used by the species in selecting its breeding habitat, or one of the possible strategies operating alone. The other strategies are group adherence mechanisms, and also the effect of conspecific attraction. At the individual level we failed to find evidence of habitat copying and only the previous success of an individual affected its fidelity to a subcolony. The importance of the lack of environmental predictability in the system is discussed, as predictability is a prerequisite of habitat copying.     

Spatial and temporal dynamics of habitat selection across canopy gradients generates patterns of species richness and composition in aquatic beetles

Abstract 1. Colonisation is a critical ecological process influencing both population and community level dynamics by connecting spatially discrete habitat patches. How communities respond to both natural and anthropogenic disturbances, furthermore, requires a basic understanding of how any environmental change modifies colonisation rates. For example, disturbance‐induced shifts in the quantity of forest cover surrounding aquatic habitats have been associated with the distribution and abundance of numerous aquatic taxa. However, the mechanisms generating these broad and repeatable field patterns are unclear. 2. Such patterns of diversity could result from differential spatial mortality post colonisation, or from colonisation alone if species select sites non‐randomly along canopy coverage gradients. We examined the colonisation/oviposition dynamics of aquatic beetles in experimental ponds placed under both open and closed forest canopies. 3. Canopy coverage imposed a substantial behavioural filter on the colonisation and reproduction of aquatic beetles representing multiple trophic levels, and resulted in significantly higher abundance, richness, and oviposition activity in open canopy ponds. These patterns strengthened overtime; although early in the experiment, the most abundant beetle had similar abundance in open and closed ponds. However, its abundance subsequently declined and then most other species heavily colonised open canopy ponds. 4. The primary response of many aquatic species to disturbances that generate canopy coverage gradients surrounding aquatic ecosystems is behavioural. The magnitude of the colonisation responses reported here rivals, if not exceeds, those produced by predators, suggesting that aquatic landscapes are behaviourally assessed and partitioned across multiple environmental gradients. The community level structure produced solely by selective colonisation, is predicted to strongly modify how patch area and isolation affect colonisation rates and the degree to which communities are linked by the flux of individuals and species.     

Spatial patterns of coexistence of competing species in patchy habitat

The single-species spatially realistic patch occupancy metapopulation model is, in this study, extended to a metacommunity of many competing species. Competition is assumed to reduce the local carrying capacity (effective patch area), which in turn increases local extinction rates and reduces colonization rates because of smaller population sizes. Each species is described by three parameters: pre-competitive abundance (equilibrium incidence of patch occupancy, which reflects the rate of colonization in relation to extinction rate), the spatial range of migration, and competitive ability. The model ignores spatio–temporal correlations caused by interspecific interactions, because in metacommunities of unequal competitors inhabiting heterogeneous landscapes, correlations in the occurrence of species are driven more by patch heterogeneity than by competition. The model allows the calculation of multispecies equilibria in patchy habitats without simulations. In general, the number of coexisting species in the metacommunity increases with decreasing strength of competition, increasing rate of colonization, and decreasing range of migration. Habitat heterogeneity in the form of spatial variation in patch areas tends to facilitate coexistence. Poor competitors may coexist with superior competitors in the patch network if the former have higher colonization rates (competition–colonization trade-off). When migration distances are short, competition leads to spatial pattern formation: Species tend to have restricted spatial distributions in the network, but contrary to intuitive expectations, often the distributions of many species are nested. Having more dispersive species enhances both local and global diversity, whereas more local migration decreases local but increases global diversity.     

Multi-scale habitat selection affects offspring survival in a precocial species

In theory, habitat preferences should be adaptive. Accordingly, fitness is often assumed to be greater in preferred habitats; however, this assumption is rarely tested and, when it is, the results are often equivocal. Habitat preferences may not directly convey fitness advantages if animals are constrained by tradeoffs with other selective pressures like predation or food availability. We address unresolved questions about the survival consequences of habitat choices made during brood-rearing in a precocial species with exclusive maternal care (mallard Anas platyrhynchos, n = 582 radio-marked females on 27 sites over 8 years). We directly linked duckling survival with habitat selection patterns at two spatial scales using logistic regression and model selection techniques. At the landscape scale (55–80 km²), females that demonstrated stronger selection of areas with more cover type 4 wetlands and greater total cover type 3 wetland area (wetlands with large expanses of open water surrounded by either a narrow or wide peripheral band of vegetation, respectively) had lower duckling survival rates than did females that demonstrated weaker selection of these habitats. At finer scales (0.32–7.16 km²), females selected brood-rearing areas with a greater proportion of wetland habitat with no consequences for duckling survival. However, females that avoided woody perennial habitats composed of trees and shrubs fledged more ducklings. The relationship between habitat selection and survival depended on both spatial scale and habitats considered. Females did not consistently select brood-rearing habitats that conferred the greatest benefits, an unexpected finding, although one that has also been reported in other recent studies of breeding birds.     

Habitat change and the scale of habitat selection: shifting gradients used by coexisting Arctic rodents

The conservation and understanding of biodiversity requires development and testing of models that illustrate how climate change and other anthropogenic effects alter habitat and its selection at different spatial scales. Models of fitness along a habitat gradient illustrate the connection between fine‐scale variation in fitness and the selection of habitat as discontinuous patches in the landscape. According to these models, climate change can increase fitness values of static habitats, shift the fitness value of habitat patches along underlying gradients of habitat quality, or alter both fitness and habitat quality. It should be possible to differentiate amongst these scenarios by associating differences in the abundance and distribution of species with metrics of habitat that document the gradient while controlling for changes in density at larger scales of analysis. Comparisons of habitat selection by two species of lemmings, over an interval of 15 years, are consistent with the theory. The pattern of habitat selection at the scale of wet versus dry tundra habitats changed through time. The change in habitat selection was reflected by different, but nevertheless density‐dependent, patterns of association with the structure and composition of habitat. Abundant collared lemmings abandoned stations where altered habitat characteristics caused a shift to new locations along the wet‐to‐dry gradient. The confirmation of scale‐dependent theory provides new insights into how one might begin to forecast future habitat selection under different scenarios of climate and habitat change.     

Experiments on habitat selection of Heterophyes species in different definitive hosts

Heterophyes heterophyes, H. aequalis and H. dispar showed distinct zonation in the small intestine of different definitive hosts. The flukes were found in their appropriate zone within four to six hours after infection. It appeared that their position shifted posteriorly during their life and that the shift proceeded more rapidly in unsuitable hosts. Histological sections revealed that the flukes are not deeply embedded in the host's mucosa.     

Spatial patterns and interspecific relations analysis help to better understand species distribution patterns in a Mediterranean high mountain grassland

The aim of this study is to investigate distribution patterns of species occurring at definite spatial scales and to address the main ecological factors that structure a Mediterranean high mountain grassland community. Following the protocols of the GLORIA long-term study, four summits were sampled during the year 2006 and 2007 in Sierra de Guadarrama (Spain). The data recorded on two of those summits were analysed for spatial pattern of species, interspecific associations and environmental relationships were determined from the recorded data. This was done by multivariate analyses (ordinations), SADIE analyses (distance indices) and Pearson χ² test, respectively. Results showed that chamaephyte species were more abundant in less disturbed situations whilst caespitose hemicryptophyte species and mosses were more abundant in disturbed ones. High mountain species were more abundant in less disturbed situations. Higher spatial heterogeneity was detected on northern and eastern slopes, which could be related to the increased environmental severity of northern exposures and to the greater intensity of the disturbances on eastern exposures. The frequent aggregated distribution of a few species may be related to facilitation processes due to their frequent participation in positive interactions. Finally we observed that positive pairwise associations of species were more frequent than negative associations. The relevance of the studied relationships lied in a better understanding of those threats on high mountain biodiversity induced by climate warming.