Habitat selection at multiple spatial scales by foraging Glossy Black‐cockatoos

Abstract: Habitat selection among vertebrates entails decision making at a number of spatial scales. An understanding of factors influencing decisions at each of these scales is required for the effective management of wildlife populations. This study investigates the foraging ecology of a population of Glossy Black‐cockatoos in central New South Wales. We took advantage of the characteristic feeding sign produced by Glossy Black‐cockatoos to examine factors influencing habitat selection at multiple spatial scales. Birds preferred to forage at sites where food was abundant and avoided open sites where the predation risk may be greater. Their two food species, Allocasuarina diminuta and Allocasuarina gymnanthera, differed in profitability (kernel intake rate as measured by the ratio of seed weight to total seed and cone weight), as did trees within a species. Both species were utilized extensively, although foraging intensity was greater at sites where the more profitable species was present. In order to maximize their food intake, birds selected individual trees on the basis of cone abundance and profitability. Cones produced in the previous year were preferred.     

Habitat selection by a large herbivore at multiple spatial and temporal scales is primarily governed by food resources

Habitat selection can be considered as a hierarchical process in which animals satisfy their habitat requirements at different ecological scales. Theory predicts that spatial and temporal scales should co‐vary in most ecological processes and that the most limiting factors should drive habitat selection at coarse ecological scales, but be less influential at finer scales. Using detailed location data on roe deer Capreolus capreolus inhabiting the Bavarian Forest National Park, Germany, we investigated habitat selection at several spatial and temporal scales. We tested 1) whether time‐varying patterns were governed by factors reported as having the largest effects on fitness, 2) whether the trade‐off between forage and predation risks differed among spatial and temporal scales and 3) if spatial and temporal scales are positively associated. We analysed the variation in habitat selection within the landscape and within home ranges at monthly intervals, with respect to land‐cover type and proxys of food and cover over seasonal and diurnal temporal scales. The fine‐scale temporal variation follows a nycthemeral cycle linked to diurnal variation in human disturbance. The large‐scale variation matches seasonal plant phenology, suggesting food resources being a greater limiting factor than lynx predation risk. The trade‐off between selection for food and cover was similar on seasonal and diurnal scale. Habitat selection at the different scales may be the consequence of the temporal variation and predictability of the limiting factors as much as its association with fitness. The landscape of fear might have less importance at the studied scale of habitat selection than generally accepted because of the predator hunting strategy. Finally, seasonal variation in habitat selection was similar at the large and small spatial scales, which may arise because of the marked philopatry of roe deer. The difference is supposed to be greater for wider ranging herbivores.     

Habitat selection by helminths: a hypothesis

How do liver worms find the liver? Why are heartworms always found in the heart? Attempts to answer these questions have invariably yielded inconclusive results. A major problem has been the use of models or hypotheses derived from studies of free-living organisms. The parasite's environment is distinct from free-living environments in several fundamental ways and these differences will impact on the evolution of parasite behaviours. In this article, Michael Sukhdeo outlines a hypothesis for habitat selection behavior of helminths that is based on the specific environmental conditions within the host.     

Winter foraging by muskoxen: a hierarchical approach to patch residence time and cratering behaviour

We examined the temporal and spatial patterns of feeding behaviours of muskoxen during winter in the High Arctic. Pawing motions (to uncover forages beneath snow cover) were strongly aggregated into temporal bouts. Similarly, feeding stations (areas exploitable without motion of the forelegs) were aggregated into spatial patches. Muskoxen responded to greater snow accumulation at feeding sites by increasing the rates of pawing, rates of pawing bouts, number of pawing strokes per bout, and station residence times. Patch residence times showed little relationship to snow or forage abundance because, as muskoxen increased station residence times, they decreased the number of stations per patch. Muskoxen displaced one another from feeding stations more frequently as snow thickness and group size increased. Time spent at feeding stations was positively correlated to travel costs, in accordance with the marginal value model of patch residence. The model was not supported, however, at the scale of the feeding patch. The results indicate that behavioural responses of muskoxen to foraging conditions differ across scales.     

Habitat selection and foraging success by an endangered Mediterranean cyprinid: implications for habitat restoration

Hydrobiologia - Habitat loss and degradation are causing collapses in freshwater fish in the Mediterranean region, where habitat restoration actions are still hampered by poor understanding of fish...     

Habitat selection as a hierarchical spatial process: the green woodpecker at the northern edge of its distribution range

Habitat selection can be envisaged as a hierarchical spatial process, from choice of home range to choice of dietary item. The green woodpecker (Picus viridis) is described as being closely bound to cultivated land and deciduous forests, mainly due to its summer diet composed of ants (Hymenoptera: Formicidae) found on meadows and pastures. To explore possible responses of this woodpecker to recent changes in land use practice, we studied home ranges, feeding habitats and food selection of a marginal population (four radio-marked males and five females) in a 30,000-ha conifer-dominated landscape at the northern edge of its distribution range in south-central Scandinavia. We asked: (1) Is the green woodpecker confined to areas with cultivated land and deciduous forest? (2) If so, are important food items (ants) particularly abundant or exclusively found there? (3) Can clearcuts and young plantations substitute for cultivated land as feeding habitat? Home ranges (mean=100 ha) were invariably confined to the parts of the landscape that contained cultivated land (<1% of the total area). In summer, birds preferred to feed in cultivated land, presumably due to a higher overall biomass of ants compared to forest habitats. They avoided clearcuts, but preyed extensively upon soil-dwelling ants in young conifer stands (16–30 years old). We failed to find preferences for particular ant groups (Lasius niger and L. flavus) associated with cultivated land. The principal summer food was Serviformica, an ant group that was equally abundant in cultivated land and forest habitat. A positive correlation between ant body mass and a preference index suggests that the birds selected the larger ant species independent of habitat type. In winter, birds fed exclusively on mound-building Formica rufa-ants in closed-canopy, older forest stands. Our results indicate that the green woodpecker successfully utilizes young conifer plantations as feeding habitat. At a larger scale, we hypothesize that green woodpecker populations fail to establish in managed forest tracts, not because of food shortage, but because the landscapes lack cultivated land serving as a key stimulus encouraging individuals to settle.     

Habitat selection and aggression as determinants of spatial segregation among damselfish on a coral reef

Adults of many closely related coral reef fish species are segregated along gradients of depth or habitat structure. Both habitat selection by new settlers and subsequent competitive interactions can potentially produce such patterns, but their relative importance is unclear. This study examines the potential roles of habitat selection and aggression in determining the spatial distribution of adults and juveniles of four highly aggressive damselfishes at Lizard Island, northern Great Barrier Reef. Dischistodus perspicillatus, D. prosopotaenia, D. melanotus, and D. pseudochrysopoecilus maintain almost non-overlapping distributions across reef zones, with adults of one species dominating each reef zone. Juveniles exhibit slightly broader distributional patterns suggesting that subsequent interactions reduce overlap among species. Although habitat choice experiments in aquaria suggest that associations between juveniles and substrata types in the field are partly due to habitat selection, large overlaps in the use of substrata by the different species were also found, suggesting that substratum selection alone is insufficient in explaining the discrete spatial distributions of adults. The strength of aggressive interactions among all four species was tested by a "bottle" experiment, in which an adult or juvenile of each species was placed in the territories of adult fish on the reef. The greatest levels of interspecific aggression were directed against adults and juveniles of neighbouring species. The highest levels of aggression were associated with species exhibiting the greatest levels of overlap in resource use. Evidently both habitat selection and interspecific aggression combine to determine the adult distributions of these species.     

Habitat selection as a source of biological diversity

Summary Question: What are the conditions required for natural selection to produce phenotypes specially adapted to the various habitats available in nature? Model: Assume there are two habitat types and one or two phenotypes of the same or different species. The phenotypes do not recognize any spatial differences among patches of the same habitat type. Possible evolutionary winners can do better in one habitat only by relinquishing some ability in the other. Results: If only one phenotype is present, it will be an intermediate (unless one of the two habitat types is so rare and unproductive that its effects can be ignored by natural selection). Even if two phenotypes are introduced, natural selection should generally restore monomorphism if habitat selection is not ever favored (e.g. if search costs are high). But if search costs and environmental variation are zero, dimorphism can be expected. And if they are small, then although monomorphism is stable, its basin of attraction is small, and invasion by a second form (such as a sibling species) can provide the discontinuous jump needed to put the system in the other basin of attraction. Once there, dimorphic extremism coevolves. Each successful morph is as specialized as possible on one of the habitats. Competition between the morphs is eliminated. Environmental variation may constrict the basin, but once a point is captured by it, the system approaches dimorphic extremism anyway. In general, whatever promotes the behavior of habitat selection also promotes the evolution of extreme morphologies and physiologies.     

Habitat selection and foraging behaviour of breeding Eurasian Woodcock Scolopax rusticola: a comparison between contrasting landscapes

Diet, feeding behaviour and habitat selection of breeding Eurasian Woodcock Scolopax rusticola were studied by radiotracking birds from March to July in two contrasting situations: a 171-ha lowland plantation of Sycamore Acer pseudoplatanus , Beech Fagus sylvaticus and pine Pinus sylvestris / P. nigra in Derbyshire, central England, and an area of c . 900 ha of fragmented, naturally regenerating birch Betula pendula / B. pubescens woodland and hill margin in an upland glen in Angus, northeast Scotland. Earthworms were the most important diet component of adults and chicks in terms of biomass at both sites (50–80%), the rest comprising mainly spiders, harvestmen and beetles. In spring both sexes flew c . 1 km after dusk to feed on fields at night, with up to 94% of nocturnal radiolocations on fields in March, dropping to 18% in July. This behaviour probably reflected seasonal changes in the relative availability of earthworms in fields and woodland. Diurnal home range sizes were similar at both sites and the mean size of 30-day ranges was 62 ± 20 ha (± se), although Woodcock changed locations regularly and areas used for feeding on a daily basis were typically smaller than 1 ha. In the lowland plantation, Sycamore with Dog's Mercury Mercurialis perennis ground cover was highly used relative to availability. In the upland margin study area, the same held for dense sapling-stage birch. These habitats appear to represent a compromise between food availability and protection from avian predators. Recently documented changes in the structure of British woods during the last 30 years, suggestive of reduced management and increased grazing/browsing, are likely to have been detrimental to breeding Woodcock.     

Accuracy of resource selection functions across spatial scales

Resource selection functions (RSFs) can be used to map suitable habitat of a species based on predicted probability of use. The spatial scale may affect accuracy of such predictions. To provide guidance as to which spatial extent or grain is appropriate and most accurate for animals, we used the concept of hierarchical selection orders to dictate extent and grain. We conducted a meta-analysis from 123 RSF studies of 886 species to identify differences in prediction success that might be expected for five selection orders. Many studies do not constrain spatial extent to the grain of the next broader selection order in the hierarchy, mixing scaling effects. Thus, we also compared accuracy of single- vs. multiple-grain RSFs developed at the unconstrained extent of an entire study area. Results suggested that the geographical range of a species was the easiest to predict of the selection orders. At smaller scales within the geographical range, use of a site was easier to predict when environmental variables were measured at a grain equivalent to the home-range size or a microhabitat feature required for reproduction or resting. Selection of patches within home ranges and locations of populations was often more difficult to predict. Multiple-grain RSFs were more predictive than single-grain RSFs when the entire study area was considered available. Models with variables measured at both small and large (> 100 ha) grains were usually most predictive, even for many species with small home ranges. Multiple-grain models may be particularly important for species with moderate dispersal abilities in habitat fragments surrounded by an unsuitable matrix. We recommend studies should no longer address only one grain to map animal species distributions.     

Habitat selection in spatially heterogeneous environments: a test of foraging behaviour in the clonal submerged macrophyte Vallisneria spiralis

1. To test whether clonal macrophytes can select favourable habitats in heterogeneous environments, clonal fragments of the stoloniferous submerged macrophyte Vallisneria spiralis were subjected to conditions in which light intensity and substratum nutrients were patchily distributed. The allocation of biomass accumulation and ramet production of clones to the different patches was examined. 2. The proportion of both biomass and ramet number of clones allocated to rich patches was significantly higher than in poor patches. The greatest values of both clone and leaf biomass were produced in the heterogeneous light treatment, in which clones originally grew from light‐rich to light‐poor patches, while clones produced the most offspring ramets in the treatments with heterogeneous substratum nutrients. Similarly, root biomass had the highest values in nutrient‐rich patches when clones grew from nutrient‐rich to nutrient‐poor patches. 3. The quality of patches in which parent ramets established significantly influenced the foraging pattern. When previously established in rich patches, a higher proportion of biomass was allocated to rich patches, whereas a higher proportion of ramet number was allocated to rich patches when previously established in poor patches. 4. Results demonstrate that the clonal macrophyte V. spiralis can exhibit foraging in submerged heterogeneous environments: when established under resource‐rich conditions V. spiralis remained in favourable patches, whereas if established in adverse conditions it could escape by allocating more ramets to favourable patches.     

Habitat selection by the Spiny-tailed lizard (Uromastyx aegyptia): A view from spatial analysis

Many factors affect the habitat selection for animal species, which in turn may greatly affect their distribution in different ecosystems. Understanding the processes that affect habitat selection is also critical for guiding and managing conservation initiatives. Our study aimed to assess the habitat selection by free-ranging Spiny-tailed lizard (Uromastyx aegyptia) by analyzing a geospatial data connecting its burrow parameters to different habitat characteristics within selected sites in Hail region, Saudi Arabia. We examined evidence and patterns of significant spatial clustering for (366) active burrows by linking their parameters (burrow entrance size, burrow entrance width and burrow entrance height), their reference geographical locations and, two habitat characteristics defined by soil type and vegetation cover. The objective of the analysis was to increase the understanding on the burrows aggregation process in the space and, to describe its possible relation to other spatial habitat configurations. Analysis of distances based on the Nearest Neighbor Index (NNI) and hotspots detection in Nearest neighbor hierarchical clustering (Nnh) suggested twelve (12) spatial clusters located within the study area. In addition, a spatial ordinary least square (OLS) and Poisson regression models revealed significant effects of soil type and vegetation cover on burrow parameters (OLS, p < 0.05; Poisson, p < 0.001), which indicate a strong association between burrows parameters and habitats characteristics. Findings from the study also suggest that other factors such as elevations, highways, and human settlement concentration spots could possibly play a major role in defining burrow spatial aggregation and furthermore have a significant impact on habitat selection.     

Habitat use and foraging behaviour of urban merlins (Falco columbarius) in winter

Habitat use and foraging behaviour of resident merlins (Falco columbarius) wintering in Saskatoon, Canada, were studied over a five-year period. Birds were trapped through the winter and selected individuals fitted with radio transmitters to monitor continously their location, movements and activities from roost departure until re-entry. Merlins maintained individual home ranges in winter, with extensive overlap between neighbouring birds in some cases. Yearling home ranges were not significantly different in size from those of adults. The winter home ranges of adults were closely associated with their previous nest site. Both adults and yearlings made significantly greater use of Residential habitat in the city than expected based on the area available in their home ranges. However, while adults remained largely in the two oldest habitat types, yearlings were also found in more recently built areas of the city. Home ranges held within the city were sometimes combined with foraging areas in the adjacent countryside. The use of foraging areas in farmyards and cattle feedlots outside of the city was most notable in adults, although some yearlings apparently learned this strategy in their first year. Merlins also used Commercial-Industrial habitat for hunting at levels much higher than expected from its availability in their home ranges. Diets in summer and winter had a high degree of overlap; house sparrows (Passer domesticus) and bohemian waxwings (Bombycilla garrulus) made up a large proportion of the diet during both seasons. Hunting activity peaked at 09:00 and 16:00 h, reflecting the replenishment of energy stores lost over-night, and the storage of energy in preparation for the next over-night fast.     

Habitat selection by a threatened desert amphibian

Habitat degradation and fragmentation are major drivers of amphibian declines. The loss of environmental features that allow for movement between water sources may be particularly detrimental for amphibians in arid environments. Climate changes will increase the importance of microhabitats to amphibians. Enhancing areas to facilitate movement may be a necessary conservation strategy for many animal species that depend on wetlands, including federally threatened Chiricahua leopard frogs (Lithobates chiricahuensis). Habitat preferences of this frog species are not well understood. We sought to better understand fine‐scale habitat selection, to inform conservation of Chiricahua leopard frogs. We conducted our study on the Ladder Ranch, a privately owned working bison ranch in New Mexico, USA that supports a large proportion of the remaining Chiricahua leopard frogs in the state. We attached radio transmitters to 44 frogs during summer 2014. We located each frog daily for up to 8 weeks (median = 30 days). We assessed fine‐scale habitat selection by comparing characteristics at each frog location and a random location 5 m away using conditional logistic regression. Frogs preferred features that likely reduce desiccation, even after accounting for the presence of water. Frogs selected areas with more low‐lying cover, especially aquatic vegetation and woody debris, a tree overstory, and a mud substrate. We recommend managing potential movement corridors for Chiricahua leopard frogs by ensuring the presence of muddy creek bottoms, woody debris, riparian overstory, low‐lying ground cover, and pools. Microclimates created by these features seem especially valuable given warming temperatures and modified precipitation regimes, resulting in decreased surface water, soil moisture, and vegetation cover. Retaining or creating preferred habitat features and microclimates in areas between water sources may increase connectivity among isolated populations of Chiricahua leopard frogs and could improve persistence and recovery of other water‐obligate species in arid landscapes.     

Optimal foraging as the criteria of prey selection by two centrarchid fishes

The nature of prey selection by two centrarchids (white crappie and bluegill) is presented as a model incorporating optimal foraging strategies. The visual field of the foraging fish as represented by the reactive distance is analysed in detail to estimate the number of prey encounters per search bout. The predicted reactive distances are compared with experimental data. The energetic cost associated with fish foraging behaviour is calculated based on the sequence of events that takes place for each prey consumed. Comparisons of the relative abundance of prey species and size categories in the stomach to the lake environment indicated that both white crappie and bluegill (length < 100 mm) strongly select prey utilising an energy optimization strategy. In most cases, the fish exclusively selected large Daphnia ignoring evasive prey types (Cyclops, Diaptomids) and small cladocera. This selectivity is the result of fish actively avoiding prey with high evasion capabilities even though they appear to be high in energetic content and having translated this into optimal selectivity through capture success rates. The energy consideration and visual system, apart from the forager's ability to capture prey, are the major determinants of prey selectivity for large-sized bluegill and white crappie still at planktivorous stages.