Spatial and temporal scaling in habitat utilization by klipspringers (Oreotragus oreotragus) determined using giving‐up densities

An animal's pattern of habitat use can reveal how different parts of its environment vary in quality based on the costs (such as predation risk) and benefits (such as food intake) of using each habitat. We studied klipspringer habitat use in Augrabies Falls National Park, South Africa using giving‐up densities (GUDs; the amount of food remaining in a resource patch following exploitation) in experimental food patches. We tested hypotheses related to how salient habitat variables might influence klipspringers' perceptions of foraging costs. At small spatial scales (3–4 m), klipspringer GUDs did not vary with cover and open microhabitats, or with the four cardinal aspects (shading) around shrubs. Adding water adjacent to food patches did not influence GUDs, showing that water is not a limiting complementary resource to food. Generally, klipspringers do not appear to be physiologically constrained. There was no difference in GUDs between four daily time periods, or between summer and winter; however, a significant interaction effect of time‐of‐day with season resulted from GUDs during the midday time period in winter being significantly higher (perceived value lower) than during the same time period in summer. At moderate spatial scales (10–60 m), klipspringer GUDs increased with distance from rocks because of increased predation risk. Based on GUDs collected at the largest scale (two 4.41‐ha grids), klipspringers preferred foraging at greater distances from drainage lines and on pebble and cobble substrates. Overall, this study has shown the efficacy of measuring GUDs to determine klipspringers' habitat utilization while foraging.     

Habitat and patch use by hyraxes: there’s no place like home?

Models of central place foraging predict that animals should forage more thoroughly in resource patches located closer to the central place. Travel time, cost of transporting food back to the central place, and exposure to predators should all act to increase foraging costs with increasing distance from the refuge. We examined habitat and patch use in rock hyraxes ( Procavia capensis ) inhabiting a group of kopjes in a semiarid savanna, Augrabies Falls National Park, South Africa. We tested the prediction of more intense patch use closer to the central place by measuring giving-up densities (GUDs) in experimental resource patches set at four different distances from the kopje and in two microhabitats differing in cover. Surprisingly, hyraxes had their lowest GUDs at intermediate distances from the kopje. These unexpected results suggest that the sentinel behaviour of hyraxes alters the probability of detection of predators for animals foraging away from the kopje.     

The effects of habitat manipulation on population distribution and foraging behavior in meadow voles

Individuals, free to choose between different habitat patches, should settle among them such that fitness is equalized. Alternatives to this ideal free distribution result into fitness differences among the patches. The concordance between fitnesses and foraging costs among inhabitants of different quality patches, demonstrated in recent studies, suggests that the mode of habitat selection and the resulting fitness patterns may have important implications to the resource use of a forager and to the survival of its prey. We studied how coarse scale selection between habitat patches of different quality and quitting harvest rate in these patches are related to each other and to fine scale patch use in meadow voles (Microtus pennsylvanicus). To demonstrate these relationships, we manipulated habitat patches within large field enclosures by mowing vegetative cover and adding supplemental food according to a 2×2 factorial design. We tracked vole population densities, collected giving‐up densities (GUDs, a measure of patch quitting harvest rate), and monitored the removal of seeds from lattice grids with 1.5 m intervals (an index of fine‐scale space use) in the manipulated habitat patches. Changes in habitat quality induced changes in habitat use at different spatial scales. In preferred habitats with intact cover, voles were despotic and GUDs were low, but increased with the addition of food. In contrast, voles in less‐preferred mowed habitats settled into an ideal free distribution, GUDs were high and uninfluenced by the addition of food. Seed removal was enhanced by the presence of cover but inhibited by supplemental food. Across all treatments, vole densities and GUDs were strongly correlated making it impossible to separate their effects on seed removal rates. However, this relationship broke down in unmowed habitats, where GUDs rather than vole density primarily influenced seed removal by voles. GUDs and seed removal correlated with predation on tree seedlings formerly planted into the enclosures, demonstrating the mechanisms between coarse‐scale habitat manipulations and community level consequences on a forager's prey.     

Variation of within-day foraging costs in the striped mouse (Rhabdomys pumilio)

Foraging behavior is influenced by spatial and temporal habitat heterogeniety. Here we report on within-day foraging and perceived risk of predation by the striped mouse (Rhabdomys pumilio) in a grassland savannah with wooded “islands” using giving-up densities (GUD, amount of food left behind in depletable food patches). Higher GUDs correspond to higher forging costs. GUDs were measured six times per day at 2-h intervals from paired stations along fern–grass habitat boundaries at 3 and 6 m distances from 10 wooded islands. R. pumilio's GUDs varied significantly over the course of the day with highest GUDs during the afternoon hours of 1–3 pm, and lowest between 7 and 9 am in the morning. The same pattern was consistent for both habitats (fern and grass) and distances from the wooded islands. GUDs decreased with distance from the woody islands in both fern and grass habitats and were significantly lower in the fern habitat. This activity pattern suggests that R. pumilio responds to a spectrum of spatially and temporally varying risks from a variety of predators including aerial predators that increase risk as they make use of mid-day thermals.     

Foraging costs and accessibility as determinants of giving-up densities in a swan-pondweed system

We measured the patch use behaviour of Bewick's swans (Cygnus columbianus bewickii) feeding on below ground tubers of fennel pondweed (Potamogeton pectinatus). We compared the swans’ attack rates, foraging costs and giving‐up densities (GUDs) in natural and experimental food patches that differed in water depth. Unlike most studies that attribute habitat‐specific differences in GUDs to predation risk, food quality or foraging substrate, we quantified the relative importance of energetic costs and accessibility. Accessibility is defined as the extent to which the animal's morphology restricts its harvest of all food items within a food patch. Patch use behaviours were measured at shallow (ca 0.4 m) and deep (ca 0.6 m) water depths on sandy sediments. In a laboratory foraging experiment, when harvesting food patches, the swan's attack rate (m³ s^?1) did not differ between depths. In deep water the energetic costs of surfacing, feeding and trampling were 1.13 to 1.21 times higher than in shallow water with a tendency to spend relatively more time trampling, the most expensive activity. Taking time allocation as measured in the field into account, foraging in deep water was 1.26 times as expensive as in shallow water. In the lake the GUD in shallow water was on average 12.9 g m^?2. If differences in energetic costs were the only factor determining differences in GUDs, then the deep water GUD should be 14.2 g m^?2. Instead, the mean GUD in deep water was 20.2 g m^?2, and therefore energetic costs explain just 18% of the difference in GUDs. At deep sites, 24% of tuber biomass was estimated to be out of reach, and we calculated a maximum accessible foraging depth of 0.86 m. This is close to the published 0.84 m based on body measurements. A laboratory experiment with food offered at a depth of 0.89 m confirmed that it was just out of reach. The agreement between calculated and observed maximum accessible foraging depths suggests that accessibility largely explains the remaining difference in GUDs with depth, and it confirms the existence of partial prey refuges in this system.     

Scales and costs of habitat selection in heterogeneous landscapes

Summary Two scales of habitat selection are likely to influence patterns of animal density in heterogeneous landscapes. At one scale, habitat selection is determined by the differential use of foraging locations within a home range. At a larger scale, habitat selection is determined by dispersal and the ability to relocate the home range. The limits of both scales must be known for accurate assessments of habitat selection and its role in effecting spatial patterns in abundance. Isodars, which specify the relationships between population density in two habitats such that the expected reproductive success of an individual is the same in both, allow us to distinguish the two scales of habitat selection because each scale has different costs. In a two-habitat environment, the cost of rejecting one of the habitats within a home range can be expressed as a devaluation of the other, because, for example, fine-grained foragers must travel through both. At the dispersal scale, the cost of accepting a new home range in a different habitat has the opposite effect of inflating the value of the original habitat to compensate for lost evolutionary potential associated with relocating the home range. These costs produce isodars at the foraging scale with a lower intercept and slope than those at the dispersal scale.Empirical data on deer mice occupying prairie and badland habitats in southern Alberta confirm the ability of isodar analysis to differentiate between foraging and dispersal scales. The data suggest a foraging range of approximately 60 m, and an effective dispersal distance near 140 m. The relatively short dispersal distance implies that recent theories may have over-emphasized the role of habitat selection on local population dynamics. But the exchange of individuals between habitats sharing irregular borders may be substantial. Dispersal distance may thus give a false impression of the inability of habitat selection to help regulate population density.     

The Ecology of fear: host foraging behavior varies with the spatio-temporal abundance of a dominant ectoparasite

Prey engage in myriad behaviors to avoid predation, and these indirect effects of predators on their prey are often measured by the amount of food abandoned by a forager (the "giving-up density", or GUD) in a given habitat. Recent evidence suggests that hosts may engage in comparable behaviors to avoid exposure to parasites. We investigated changes in local foraging and regional space use by mammal hosts for the lone star tick (Amblyomma americanum), using GUDs as an indicator of the perceived risk of parasitism. At eight study sites at the Tyson Research Center (Eureka, MO), we placed two feeding trays, one on the ground and one at 1.5 m height in a tree, in order to assess how the emergence of ground-dwelling ticks affected foraging by several mammal species both locally (between the two GUD stations) and regionally (among the eight sites, mean distance 1064 m apart). Though GUDs did not differ between the ground and tree GUD stations, we did find that greater amounts of food were "given-up" at sites with higher abundances of ticks. This increase in food abandonment suggests that hosts respond to the risk of parasitism and alter their space use accordingly, potentially affecting a cascade of other ecological interactions across large spatial scales.     

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.     

Assessing habitat quality of farm-dwelling house sparrows in different agricultural landscapes

Having historically been abundant throughout Europe, the house sparrow (Passer domesticus) has in recent decades suffered severe population declines in many urban and rural areas. The decline in rural environments is believed to be caused by agricultural intensification, which has resulted in landscape simplification. We used giving-up densities (GUDs) of house sparrows feeding in artificial food patches placed in farmlands of southern Sweden to determine habitat quality during the breeding season at two different spatial scales: the landscape and the patch scale. At the landscape scale, GUDs were lower on farms in homogeneous landscapes dominated by crop production compared to more heterogeneous landscapes with mixed farming or animal husbandry. At the patch level, feeding patches with a higher predation risk (caused by fitting a wall to the patch to obstruct vigilance) had higher GUDs. In addition, GUDs were positively related to population size, which strongly implies that GUDs reflect habitat quality. However, the increase followed different patterns in homogeneous and heterogeneous landscapes, indicating differing population limiting mechanisms in these two environments. We found no effect of the interaction between patch type and landscape type, suggesting that predation risk was similar in both landscape types. Thus, our study suggests that simplified landscapes constitute a poorer feeding environment for house sparrows during breeding, that the population-regulating mechanisms in the landscapes differ, but that predation risk is the same across the landscape types.     

Linking foraging decisions to residential yard bird composition

Urban bird communities have higher densities but lower diversity compared with wildlands. However, recent studies show that residential urban yards with native plantings have higher native bird diversity compared with yards with exotic vegetation. Here we tested whether landscape designs also affect bird foraging behavior. We estimated foraging decisions by measuring the giving-up densities (GUD; amount of food resources remaining when the final forager quits foraging on an artificial food patch, i.e seed trays) in residential yards in Phoenix, AZ, USA. We assessed how two yard designs (mesic: lush, exotic vegetation; xeric: drought-tolerant and native vegetation) differed in foraging costs. Further, we developed a statistical model to calculate GUDs for every species visiting the seed tray. Birds foraging in mesic yards depleted seed trays to a lower level (i.e. had lower GUDs) compared to birds foraging in xeric yards. After accounting for bird densities, the lower GUDs in mesic yards appeared largely driven by invasive and synanthropic species. Furthermore, behavioral responses of individual species were affected by yard design. Species visiting trays in both yard designs had lower GUDs in mesic yards. Differences in resource abundance (i.e., alternative resources more abundant and of higher quality in xeric yards) contributed to our results, while predation costs associated with foraging did not. By enhancing the GUD, a common method for assessing the costs associated with foraging, our statistical model provided insights into how individual species and bird densities influenced the GUD. These differences we found in foraging behavior were indicative of differences in habitat quality, and thus our study lends additional support for native landscapes to help reverse the loss of urban bird diversity.     

Large-scale forest composition influences northern goshawk nesting in Wisconsin

The northern goshawk (Accipiter gentilis atricapillus) is a woodland raptor that uses a variety of forest types for nesting across its breeding range, but strongly depends on older forests with large trees and open understories. Goshawks may select nesting locations by maximizing the convergence of nesting and foraging habitats. Insights into goshawk responses to heterogeneous landscapes can be gained by examining the location of active nest sites through time and at multiple spatial scales. We examined the landscape-scale forest conditions that influenced the probability of active goshawk nests in the United States Forest Service, Chequamegon-Nicolet National Forest (CNNF) in northern Wisconsin. We used goshawk nest survey and monitoring data from 1997 to 2006 to determine the probability of an active nest site over time in relation to forest composition and road density at 3 scales (200-m, 500-m, and 1,000-m radii). Goshawk nests were located primarily in upland hardwood (64%), conifer (23%), and older aspen–birch (≥26 yrs old; 11%) habitat cover types. We used Bayesian temporal autoregressive models of nest locations across multiple spatial scales to analyze these data. The probability of active goshawk nest occurrence increased with increasing conifer cover (1,000 m) and decreased with increasing cover of older aspen–birch and density of primary roads (500 m). In addition, lesser proportions of older aspen–birch at intermediate scales around goshawk nests had a stronger effect on the probability of a nest being active than conifer and primary roads. Thus, the ratio of conifer cover (within 1,000 m) to older aspen–birch cover (within 500 m) in landscapes surrounding nest sites was the key driver in predicting the probability of an active nest site. This finding can be used by forest managers to help sustain the active status of a goshawk nesting area through time (i.e., annually), and foster goshawk nesting activity in areas where active nesting is not currently occurring. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Do hyraxes benefit from human presence in Serengeti?

Understanding the factors affecting a species’ population size is crucial for conservation initiatives. Hyraxes are small, gregarious animals, predominantly found on kopjes (rock outcrops) and thus form metapopulation communities. In Tanzania, two species of hyraxes inhabit Serengeti National Park, the rock hyrax Procavia capensis johnstoni and bush hyrax Heterohyrax brucei. This study focuses on the factors that affect hyrax population size, including factors such as human presence, habitat type, kopje size and kopje height. We found that larger and taller kopjes tended to have more hyraxes than smaller ones, while kopjes in wooded grassland had more hyraxes than kopjes in grassland. Human presence often affects species negatively, but in the case of hyraxes, we found that kopjes with human presence had larger populations than kopjes without humans. We discuss possible explanations for this and suggest that human presence is related to fewer predators and higher food availability.     

Hierarchical Den Selection of Canada Lynx in Western Montana

Abstract We studied den selection of Canada lynx (Lynx canadensis; hereafter lynx) at multiple ecological scales based on 57 dens from 19 females located in western Montana, USA, between 1999 and 2006. We considered 3 spatial scales in this analysis, including den site (11-m-radius circle surrounding dens), den area (100-m-radius circle), and den environ (1-km radius surrounding dens). Lynx denned in preexisting sheltered spaces created by downed logs (62%), root-wads from wind-thrown trees (19%), boulder fields (10%), slash piles (6%), and live trees (4%). Lynx preferentially selected den sites with northeasterly aspects that averaged 248. Average distance between dens of 13 females monitored in consecutive years was 2,248 m, indicating low den site fidelity. Lynx exhibited habitat selection at all 3 spatial scales. Based on logistic regression, den sites differed from the surrounding den areas in having higher horizontal cover and log volume. Abundant woody debris from piled logs was the dominant habitat feature at den sites. Lynx generally denned in mature spruce-fir (Picea-Abies) forests with high horizontal cover and abundant coarse woody debris. Eighty percent of dens were in mature forest stands and 13% in mid-seral regenerating stands; young regenerating (5%) and thinned (either naturally sparse or mechanically thinned) stands with discontinuous canopies (2%) were seldom used. Female lynx selected den areas with greater spruce-fir tree basal area, higher horizontal cover, and larger-diameter trees compared to random locations within their home range. Lynx selected den environs in topographically concave or drainage-like areas, and farther from forest edges than random expectation. Maintaining mature and mid-seral regenerating spruce-fir forests with high horizontal cover and abundant woody debris would be most valuable for denning when located in drainages or in concave, drainage-like basins. Management actions that alter spruce-fir forests to a condition that is sparsely stocked (e.g., mechanically thinned) and with low canopy closure (<50%) would create forest conditions that are poorly suitable for lynx denning.     

Temporal variation in site fidelity: scale-dependent effects of forage abundance and predation risk in a non-migratory large herbivore

Large herbivores are typically confronted by considerable spatial and temporal variation in forage abundance and predation risk. Although animals can employ a range of behaviours to balance these limiting factors, scale-dependent movement patterns are expected to be an effective strategy to reduce predation risk and optimise foraging opportunities. We tested this prediction by quantifying site fidelity of global positioning system-collared, non-migratory female elk (Cervus canadensis manitobensis) across multiple nested temporal scales using a long-established elk–wolf (Canis lupus) system in Manitoba, Canada. Using a hierarchical analytical approach, we determined the combined effect of forage abundance and predation risk on variation in site fidelity within four seasons across four nested temporal scales: monthly, biweekly, weekly, daily. Site fidelity of female elk was positively related to forage-rich habitat across all seasons and most temporal scales. At the biweekly, weekly and daily scales, elk became increasingly attached to low forage habitat when risk was high (e.g. when wolves were close or pack sizes were large), which supports the notion that predator-avoidance movements lead to a trade-off between energetic requirements and safety. Unexpectedly, predation risk at the monthly scale increased fidelity, which may indicate that elk use multiple behavioural responses (e.g. movement, vigilance, and aggregation) simultaneously to dilute predation risk, especially at longer temporal scales. Our study clearly shows that forage abundance and predation risk are important scale-dependent determinants of variation in site fidelity of non-migratory female elk and that their combined effect is most apparent at short temporal scales. Insight into the scale-dependent behavioural responses of ungulate populations to limiting factors such as predation risk and forage variability is essential to infer the fitness costs incurred.     

Hazardous duty pay and the foraging cost of predation

We review the concepts and research associated with measuring fear and its consequences for foraging. When foraging, animals should and do demand hazardous duty pay. They assess a foraging cost of predation to compensate for the risk of predation or the risk of catastrophic injury. Similarly, in weighing foraging options, animals tradeoff food and safety. The foraging cost of predation can be modelled, and it can be quantitatively and qualitatively measured using risk titrations. Giving‐up densities (GUDs) in depletable food patches and the distribution of foragers across safe and risky feeding opportunities are two frequent experimental tools for titrating food and safety. A growing body of literature shows that: (i) the cost of predation can be big and comprise the forager's largest foraging cost, (ii) seemingly small changes in habitat or microhabitat characteristics can lead to large changes in the cost of predation, and (iii) a forager's cost of predation rises with risk of mortality, the forager's energy state and a decrease in its marginal value of energy. In titrating for the cost of predation, researchers have investigated spatial and temporal variation in risk, scale‐dependent variation in risk, and the role of predation risk in a forager's ecology. A risk titration from a feeding animal often provides a more accurate behavioural indicator of predation risk than direct observations of predator‐inflicted mortality. Titrating for fear responses in foragers has some well‐established applications and holds promise for novel methodologies, concepts and applications. Future directions for expanding conceptual and empirical tools include: what are the consequences of foraging costs arising from interference behaviours and other sources of catastrophic loss? Are there alternative routes by which organisms can respond to tradeoffs of food and safety? What does an animal's landscape of fear look like as a spatially explicit map, and how do various environmental factors affect it? Behavioural titrations will help to illuminate these issues and more.     

Opportunity costs influence food selection and giving‐up density of dabbling ducks

The interaction of animals with their food can yield insights into habitat characteristics, such as perceived predation risk and relative quality. We deployed experimental foraging patches in wetlands used by migrating dabbling ducks Anas spp. in the central Illinois River Valley to estimate variation in seed removal and giving‐up density (GUD; i.e. density of food remaining in patches following abandonment) with respect to seed density, seed size, seed depth in the substrate, substrate firmness, perceived predation risk, and an energetic profitability threshold (i.e. critical food density). Seed depth and the density of naturally‐occurring seeds outside of experimental plots affected seed removal and GUD in experimental patches more than perceived predation risk, seed density, seed size or substrate firmness. The greatest seed removal and lowest GUDs in experimental patches occurred when food resources in alternative foraging locations outside of plots (i.e. opportunity costs) appeared to be near or below a critical food density (i.e. 119–181 kg ha^–1). Giving‐up densities varied substantially from a critical food density across a range of food densities in alternative foraging locations suggesting that fixed GUDs should not be used as surrogates for critical food densities in energetic carrying capacity models. Foraging and resting rates in and near experimental foraging patches did not reflect patterns of seed removal and were poor predictors of GUD and foraging habitat quality. Our results demonstrated the usefulness of GUDs as indicators of habitat quality for subsurface, benthic foragers relative to other available foraging patches and suggested that food may be limited for dabbling ducks during spring migration in some years in the midwestern USA.     

Changes in spatial pattern of trees and snags during structural development in Picea mariana boreal forests

Questions : How do gap abundance and the spatial pattern of trees and snags change throughout stand development in Picea mariana forests? Does spatial pattern differ among site types and structural components of a forest? Location : Boreal forests dominated by Picea mariana, northern Quebec and Ontario, Canada. Methods : Data on the abundance, characteristics and spatial location of trees, snags and gaps were collected along 200 m transects at 91 sites along a chronosequence. Spatial analyses included 3TLQV, NLV and autocorrelation analysis. Non‐parametric analyses were used to analyse trends with time and differences among structural components and site types. Results : Gaps became more abundant, numerous and more evenly distributed with time. At distances of 1–4 m, tree cover, sapling density and snag density became more heterogeneous with time. Tree cover appeared to be more uniform for the 10–33 m interval, although this was not significant. Patch size and variance at 1 m were greater for overstorey than for understorey tree cover. Snags were less spatially variable than trees at 1 m, but more so at intermediate distances (4–8 m). Few significant differences were found among site types. Conclusions : During stand development in P. mariana forest, gaps formed by tree mortality are filled in slowly due to poor regeneration and growth, leading to greater gap abundance and clumping of trees and snags at fine scales. At broader scales, patchy regeneration is followed by homogenization of forest stands as trees become smaller with low productivity due to paludification.     

Habitat selection by the Superb Lyrebird (Menura novaehollandiae), an iconic ecosystem engineer in forests of south‐eastern Australia

Landscape heterogeneity, from both natural and anthropogenic causes, fundamentally influence the distribution of species. Conservation management requires an understanding of how species respond to heterogeneity at different spatial scales and whether differences may occur between demographic components of a species population. We examined the spatial pattern of activity of the superb lyrebird (Menura novaehollandiae), an iconic forest species of south‐eastern Australia, in the Dandenong Ranges National Park, Victoria. Specifically, we quantified at landscape and local scales, the factors that influence nest site location and foraging activity of lyrebirds. Compared with randomly located sites, nest sites were more likely to occur in wet forest or rainforest close to creek lines; where there were deep litter and complex vegetation in the mid (1.5–2 m) and high (>2 m) strata. Foraging by lyrebirds was more likely to occur in wet forest and rainforest, with increasing distance from creeks; at sites where low vegetative cover (<30 cm) was sparse and the ground layer open. Thus, lyrebirds respond to different cues for different activities (nest sites and foraging), using different resources in the landscape. These results highlight the importance of (i) knowing the range of resources, at both landscape and local scales, required by a species to ensure its persistence and (ii) adopting a landscape approach for conservation planning that incorporates the heterogeneity of the ecosystem, especially that provided by landscape components that may be limited in area but disproportionately valuable for providing habitat resources.     

Foraging in space and time structure an African small mammal community

We used live-trapping and foraging to test for the effect of habitat selection and diet on structuring a community of six small mammals and one bird within the Soutpansberg, South Africa. We established grids that straddled adjacent habitats: woodland, rocky hillside, and grassland. Trapping and foraging were used to estimate abundance, habitat use, and species-specific foraging costs. The species with the highest abundance and foraging activity in a habitat, activity time, or food was considered the most efficient and presumed to have a competitive advantage. All species exhibited distinct patterns of spatial and temporal habitat preference which provided the main mechanism of coexistence, followed by diet selection. The study species were organized into three assemblages (α diversity): grassland, Rhabdomys pumilio, Dendromus melanotis, and Mus minutoides.; woodland, Aethomys ineptus and Micaelamys namaquensis; and rock-dwelling, M. namaquensis and Elephantulus myurus. Francolinus natalensis foraged in open rocky areas and under wooded islands within the grassland. Species organization across the habitats suggested that feeding opportunities are available within all habitats; however, distinct habitat preferences resulted from differing foraging aptitudes and efficiencies of the competing species. At Lajuma, species distribution and coexistence are promoted through distinct habitat preferences that were shaped by competition and species-specific foraging costs. The combination of trapping and foraging provided a mechanistic approach that integrates behavior into community ecology by ‘asking’ the animal to reveal its perspective of the environment. Using spatial and temporal foraging decisions—as behavioral indicators—enables us to guide our understanding for across-taxa species coexistence.     

Sexual segregation of seasonal foraging habitats in a non-migratory marine mammal

Many animal species segregate by sex. Such segregation may be social in nature, or ecological, or both. Grey seals (Halichoerus grypus), like many large mammals, are sexually size dimorphic. In size dimorphic species, allometric differences in morphology, metabolic rate and reproductive costs are likely. Such differences may require the sexes to use different foraging strategies or different habitats. To investigate sexual segregation of habitat in grey seals, we used satellite tracks from 95 (male 46; female 49) adults breeding at Sable Island, Nova Scotia (44 degrees N, 60 degrees W) collected from 1995 to 2005. Location estimates were made from satellite fixes using a state-space movement model to estimate true locations and regularize them in time. Location estimates were used to calculate home range kernels of male and female habitat use each month. Month by sex kernel home ranges revealed striking differences and dynamics in habitat use between males and females on spatial scales broader than most terrestrial examples and at temporal and spatial resolutions rarely available for marine species. Differences were most pronounced just before (October-December) and immediately after breeding (February-March). During both periods, males primarily used areas along the continental shelf break, while females mainly used mid-shelf regions. Coupled with previously identified sex-specific seasonal patterns of energy storage, diving and diet, our findings suggest that males and females differ profoundly in their spatial foraging strategies. These differences may serve to maximize fitness by reducing intersexual competition during key foraging periods.