Scale for resource selection functions

Animal habitat selection is a process that functions at multiple, hierarchically. structured spatial scales. Thus multi-scale analyses should be the basis for inferences about factors driving the habitat selection process. Vertebrate herbivores forage selectively on the basis of phytochemistry, but few studies have investigated the influence of selective foraging (i.e., fine-scale habitat selection) on habitat selection at larger scales. We tested the hypothesis that phytochemistry is integral to the habitat selection process for vertebrate herbivores. We predicted that habitats selected at three spatial scales would be characterized by higher nutrient concentrations and lower concentrations of plant secondary metabolites (PSMs) than unused habitats. We used the Greater Sage-Grouse (Centrocercus urophasianus), an avian herbivore with a seasonally specialized diet of sagebrush, to test our hypothesis. Sage-Grouse selected a habitat type (black sagebrush, Artemisia nova) with lower PSM concentrations than the alternative (Wyoming big sagebrush, A. tridentata wyomingensis). Within black sagebrush habitat, Sage-Grouse selected patches and individual plants within those patches that were higher in nutrient concentrations and lower in PSM concentrations than those not used. Our results provide the first evidence for multi-scale habitat selection by an avian herbivore on the basis of phytochemistry, and they suggest that phytochemistry may be a fundamental driver of habitat selection for vertebrate herbivores.

Location‐only and use‐availability data: analysis methods converge

The Brownian bridge synoptic model of habitat selection and space use for animals using GPS telemetry data

Applications of logistic regression in a used–unused design in wildlife habitat studies often suffer from asymmetry of errors: used resource units (landscape locations) are known with certainty, whereas unused resource units might be observed to be used with greater sampling intensity. More appropriate might be to use logistic regression to estimate a resource selection function (RSF) tied to a use–availability design based on independent samples drawn from used and available resource units. We review the theoretical motivation for RSFs and show that sample “contamination” and the exponential form commonly assumed for the RSF are not concerns, contrary to recent statements by Keating and Cherry (2004; Use and interpretation of logistic regression in habitat-selection studies. Journal of Wildlife Management 68:774–789). To do this, we re-derive the use–availability likelihood and show that it can be maximized by logistic regression software. We then consider 2 case studies that illustrate our findings. For our first case study, we fit both RSFs and resource selection probability functions (RSPF) to point count data for 4 bird species with varying levels of occurrence among sample blocks. Drawing on our new derivation of the likelihood, we sample available resource units with replacement and assume overlapping distributions of used and available resource units. Irrespective of overlap, we observed approximate proportionality between predictions of a RSF and RSPF. For our second case study, we evaluate the classic use-availability design suggested by Manly et al. (2002), where availability is sampled without replacement, and we systematically introduce contamination to a sample of available units applied to RSFs for woodland caribou (Rangifer tarandus caribou). Although contamination appeared to reduce the magnitude of one RSF beta coefficient, change in magnitude exceeded sampling variation only when >20% of the available units were confirmed caribou use locations (i.e., contaminated). These empirically based simulations suggest that previously recommended sampling designs are robust to contamination. We conclude with a new validation method for evaluating predictive performance of a RSF and for assessing if the model deviates from being proportional to the probability of use of a resource unit.

BackgroundBiological control provided by natural enemies play an important role in integrated pest management. Generalist insect predators provide an important biological service in the regulation of agricultural insect pests. Our goal is to understand the explicit process of oviposition preference, habitat selection and feeding behavior of predators in farmland ecosystem consisting of multiple crops, which is central to devising and delivering an integrated pest management program.MethodologyThe hypotheses was that maize can serve as habitat for natural enemies and benefits predators to provide potential to enhance biological control for pest insects in cotton. This explicit process of a predatory beetle, Propylea japonica, in agricultural ecosystem composed of cotton and maize were examined by field investigation and stable carbon isotope analysis during 2008–2010.Principal FindingField investigation showed that P. japonica adults will search host plants for high prey abundance before laying eggs, indicating indirectly that P. japonica adults prefer to inhabit maize plants and travel to cotton plants to actively prey on aphids. The δ13C values of adult P. japonica in a dietary shift experiment found that individual beetles were shifting from a C3- to a C4-based diet of aphids reared on maize or cotton, respectively, and began to reflect the isotope ratio of their new C4 resources within one week. Approximately 80–100% of the diet of P. japonica adults in maize originated from a C3-based resource in June, July and August, while approximately 80% of the diet originated from a C4-based resource in September.Conclusion/SignificanceResults suggest that maize can serve as a habitat or refuge source for the predatory beetle, P. japonica, and benefits predators to provide potential to enhance biological control for insect pests in cotton.

Incorporating mortality into habitat selection to identify secure and risky habitats for savannah elephants

. In migrant birds, winter social systems reflect strategies of habitat use. The best-studied strategy is that of a fixed home range or territory. Alternative strategies to holding a territory, such as floating and flocking behaviors, suggest different processes of habitat selection. Whereas flocking, like territoriality, is a well-studied social strategy, solitary nonterritorial (floater) behavior is difficult to study and is thus poorly understood in terms of its causes, consequences, and implications for habitat selection. Floaters are individuals of a primarily stationary population which move over large areas compared to the average home range size. We review evidence of the causes, consequences, and frequency of winter floating behavior, focusing primarily on migrant songbirds. We also address the endocrine basis of alternative behavioral strategies by presenting results from aviary-based dominance trials with Hermit Thrushes (Catharus guttatus). Results from this study and others suggest that the adrenocortical response to social stress plays a key role in both the proximate and ultimate causes of floating behavior. Because winter floating behavior exists in many migrant songbird species, better understanding of winter floaters may be important for population modeling and conservation planning.

SummaryCharacterising the habitat use of released captive-bred birds is required to help optimise future avian reintroduction programmes. The critically endangered Double-spurred Francolin Francolinus bicalcaratus ayesha is endemic to north-west Morocco, where it inhabits forests of cork oak Quercus suber. To improve the viability of this threatened population, 300 captive-bred francolins were released into a game reserve, and post-release monitoring was conducted. This study aimed to identify habitat variables determining the habitat selection of the Double-spurred Francolin. Auditory detection was used during transect surveys of calling males to locate birds and their habitat occupation. Comparison of occupied and random plots showed that this bird is found mostly in flat topography with high cover of shrubs and dense cork oak trees, and close to the release site and water points. Conservation of Double-spurred Francolin depends on the choice of the release point within the cork oak forest, which should be in proximity to suitable cover of cork oak trees, shrubs and water points. Such choices would allow a rapid adaptation to prevailing conditions within release sites. Further multi-scale studies are needed to improve our understanding of the effects of ecological factors on the processes of habitat selection by this endemic subspecies.

ABSTRACTGrazing management recommendations often sacrifice the intrinsic heterogeneity of grasslands by prescribing uniform grazing distributions through smaller pastures, increased stocking densities, and reduced grazing periods. The lack of patch‐burn grazing in semi‐arid landscapes of the western Great Plains in North America requires alternative grazing management strategies to create and maintain heterogeneity of habitat structure (e.g., animal unit distribution, pasture configuration), but knowledge of their effects on grassland fauna is limited. The lesser prairie‐chicken (Tympanuchus pallidicinctus), an imperiled, grassland‐obligate, native to the southern Great Plains, is an excellent candidate for investigating effects of heterogeneity‐based grazing management strategies because it requires diverse microhabitats among life‐history stages in a semi‐arid landscape. We evaluated influences of heterogeneity‐based grazing management strategies on vegetation structure, habitat selection, and nest and adult survival of lesser prairie‐chickens in western Kansas, USA. We captured and monitored 116 female lesser prairie‐chickens marked with very high frequency (VHF) or global positioning system (GPS) transmitters and collected landscape‐scale vegetation and grazing data during 2013–2015. Vegetation structure heterogeneity increased at stocking densities ≤0.26 animal units/ha, where use by nonbreeding female lesser prairie‐chickens also increased. Probability of use for nonbreeding lesser prairie‐chickens peaked at values of cattle forage use values near 37% and steadily decreased with use ≥40%. Probability of use was positively affected by increasing pasture area. A quadratic relationship existed between growing season deferment and probability of use. We found that 70% of nests were located in grazing units in which grazing pressure was <0.8 animal unit months/ha. Daily nest survival was negatively correlated with grazing pressure. We found no relationship between adult survival and grazing management strategies. Conservation in grasslands expressing flora community composition appropriate for lesser prairie‐chickens can maintain appropriate habitat structure heterogeneity through the use of low to moderate stocking densities (<0.26 animal units/ha), greater pasture areas, and site‐appropriate deferment periods. Alternative grazing management strategies (e.g., rest‐rotation, season‐long rest) may be appropriate in grasslands requiring greater heterogeneity or during intensive drought. Grazing management favoring habitat heterogeneity instead of uniform grazing distributions will likely be more conducive for preserving lesser prairie‐chicken populations and grassland biodiversity. © 2021 The Wildlife Society.

Within species, individuals with different sexes, morphs and age classes often show spatial segregation. Both habitat selection and social processes have been proposed to explain intraspecific spatial segregation, but their relative importance is difficult to assess. We investigated spatial segregation between age classes in the cave salamander Hydromantes ( Speleomantes ) strinatii , and used a hypothetico‐deductive approach to evaluate whether social or ecological processes explain segregation pattern. We recorded the location and age class of salamanders along multiple caves; we measured multiple microhabitat features of different sectors of caves that may determine salamander distribution. We assessed age‐class segregation, and used generalized mixed models and an information‐theoretic framework, to test if segregation is explained by social processes or by differences in habitat selection. We found significant age‐class segregation, juveniles living in more external cave sectors than adults. Multiple environmental features varied along caves. Juveniles and adults showed contrasting habitat selection patterns: juveniles were associated with sectors having high invertebrate abundance, while adults were associated with scarce invertebrates and low temperature. When the effect of environmental features was taken into account, the relationship between juveniles and adults was non negative. This suggests that different habitat preferences, related to distinct risk‐taking strategies of age classes, can explain the spatial segregation. Juveniles require more food and select more external sectors, even if they may be risky. Conversely, adults may trade off food availability in favour of safe areas with stable micro‐climate.

Assessing habitat differentiation between coexisting species: The role of spatial scale

Evaluating relocation extent versus covariate resolution in habitat selection models across spatiotemporal scales

Changes in land use and landscape patterns constitute prominent contributors to the degradation of river water quality. The granularity of land use data resolution plays a pivotal role in delineating the spatial distribution of land use within a catchment area. Despite its significance, scant attention has been devoted to investigating the impact of land use data resolution on the interplay between catchment landscape patterns and river water quality. Employing the Yong'an River Basin in eastern China as a case study, this research leverages land use and water quality change data spanning from 1980 to 2020 to scrutinize the influence of watershed landscape patterns on changes in river water quality across varying land use resolutions (30m, 100m, 300m, 500m, 1000m). The findings reveal that alterations in the landscape pattern of grassland, urban land, rural residential land, and paddy fields significantly shape changes in river water quality within the study area. Moreover, the explanatory power of catchment landscape patterns for variations in river water quality varies under distinct data resolutions, with the highest interpretation rate observed at the 300m resolution (88.2%) and the lowest at the 1000m resolution (87.7%). The interpretation rate exhibits an initial ascent followed by a descent as data resolution decreases. Further analysis elucidates that data resolution influences the responsiveness of the landscape index to river water quality by impacting the fitting accuracy of said index. Notably, the 300m resolution exhibits superior fitting accuracy. The degree of grassland fragmentation and the concentration of construction land, along with the fragmentation and area of paddy fields, emerge as pivotal landscape factors influencing changes in river water quality within the study area. Hence, adopting an appropriate land use resolution can mitigate the impact of data redundancy and facilitate a more nuanced exploration of the driving forces behind variations in river water quality.

Foraging patches can be described as a nested hierarchy of aggregated resources, implying that study of foraging by wild animals should be directed across different spatial scales. However, almost all previous research on habitat selection by the giant panda has concentrated upon one scale. In this research, we carried out a field study to understand foraging patch selection by giant pandas in winter at both microhabitat and feeding site scales and, for the first time, attempted to understand how long it would stay at the feeding sites before moving on. The field survey was conducted from November 2002 to March 2003 at Fengtongzhai Nature Reserve (102 degrees 48'-103 degrees 00' E, 30 degrees 19'-30 degrees 47' N), Baoxing County of Sichuan Province, China, to collect data in both microhabitat and control plots. The microhabitat plots were located by fresh feces or foraging traces left by giant pandas, and the control plots were established to reflect the environment. Within each microhabitat plot, one 1x1 m2 plot was centralized at the center of each feeding site, in which numbers of old bamboos and old shoots, including eaten and uneaten, were counted, respectively. The results showed that winter microhabitats selected by this species were characteristic of gentle slopes and high old-shoot proportions and that the latter was even higher at feeding sites. Two selection processes, namely, from the environment to microhabitats and from the latter to feeding sites, were found during this species' foraging patch utilization. Giant pandas preferred to eat old shoots to old bamboo at feeding sites in winter and did not leave unless old-shoot density fell to lower than the average in the environment. Both microhabitats and feeding sites selected by giant pandas were characteristic of high old-shoot density, indicating that the preferred food item had a significant influence upon its foraging patch selection. The preference for gentle slopes by giant pandas was presumed to save energy in movement or reflect the need to sit and free its fore-limbs to grasp bamboo culms when feeding but also seemed to be correlated with an easier access to old shoots. The utilization of old shoots at feeding sites was assumed to help maximize energy or nutrient intake during their foraging. The difference between microhabitat plots and control plots and between microhabitats and feeding sites uncovered a continuous selection process from the environment via microhabitats to feeding sites. The utilization of old shoots at feeding sites was parallel to the marginal value theorem. The selection and abandonment of foraging patches by giant pandas was an optimal behavioral strategy adapted to their peculiar food with high cellulose and low protein. Our results uncovered the importance of multiple scales in habitat selection research. To further understand the process of habitat selection, future research should pay more attention to resolve the question of how to locate foraging patches under dense bamboo forests by the giant panda, which was traditionally considered to have poor eyesight, although our research has answered what type of habitats the giant panda prefers and when to leave.

Contemporary landscape change driven by socio-economic forces and advances in agricultural technology do not favor northern bobwhites (Colinus virginianus) in the Midwestern United States. The challenge of bobwhite conservation is to provide sufficient quantities of habitat with optimal configurations in proportions that satisfy needs throughout the year on private-owned working lands. We radio-tracked 58 coveys and 98 individual birds throughout the year in 2009-10 and 2010-11 on privately owned farmland in southwestern Ohio. We investigated temporal changes in usable space from use-availability data. Estimated proportions of usable space based on analyses of habitat selection across four study sites were 0.06-0.12 during the non-breeding season compared to 0.10-10.30 during the breeding season. We also modeled probabilities that radio-marked coveys or individual birds used points within individual cover types as a function of distance to other cover types. Locations of radio-marked coveys and individual birds within focal cover types were closer to other cover types compared to random points during breeding (mean = 44 m) and non-breeding (mean = 58 m) seasons. Probability of use within focal cover types declined with distance to other cover types, typically falling below 50% when distances exceeded 9-242 m. Locations of radio-marked coveys were concentrated near edges within used cover types, while locations of individual birds were more dispersed during the breeding season. Estimated proportions of usable space based on distances between locations of radio-marked bobwhites and nearest cover types were higher (0.30-0.53) than estimates based on habitat selection ratios, and were similar between non-breeding and breeding seasons. Potentially usable sites were not fully occupied in either season, but there was no relationship between crude covey densities and proportions of usable space estimated from habitat selection analyses during the breeding and non-breeding seasons across study sites and years (r2 < 0.166, P > 0.316). With distance to cover type estimates of usable space (years combined), two study sites with the highest proportions of usable space (0.43-0.53) also had the largest crude covey densities (0.0065-0.153 coveys/ha) compared to the other two sites with lower proportions of usable space (0.30-0.32) and smaller covey densities (0.004 – 0.006 coveys/ha). Habitat enhancement should focus on providing protective cover near food for coveys during the non-breeding season and protective cover near nesting and brood-rearing habitat during the breeding season. Conserving Midwestern bobwhite populations requires innovative practices that can be implemented on private lands as economic incentives change for farm operators. Improving protective cover along habitat edges can increase usable space by improving cover type juxtaposition (e.g. food near cover) while minimizing impact on farming practices.