Seasonal matching of habitat quality and fitness in a migratory bird

When species occupy habitats that vary in quality, choice of habitat can be critical in determining individual fitness. In most migratory species, juveniles migrate independently of their parents and must therefore choose both breeding and winter habitats. Using a unique dataset of marked black-tailed godwits (Limosa limosa islandica) tracked throughout their migratory range, combined with analyses of stable carbon isotope ratios, we show that those individuals that occupy higher quality breeding sites also use higher quality winter sites. This seasonal matching can severely inflate inequalities in individual fitness. This population has expanded over the last century into poorer quality breeding and winter habitats and, across the whole population; individual birds tend to occupy either novel or traditional sites in both seasons. Winter and breeding season habitat selection are thus strongly linked throughout this population; these links have profound implications for a wide range of population and evolutionary processes. As adult godwits are highly philopatric, the initial choice of winter habitat by juveniles will be critical in determining future survival, timing of migration and breeding success.     

Breeding dispersal strategies following reproductive failure explain low apparent survival of immigrant Temminck's stints

In some animal populations, immigrants have lower survival than philopatric individuals. Costs of dispersal or low phenotypic quality of dispersers may explain the pattern. However, apparent adult survival estimates, which describe real survival combined with site fidelity cannot be separated from permanent emigration. Thus, heterogeneity in breeding dispersal propensities of immigrants and philopatrics can bias fitness correlates of dispersal. Differences in breeding dispersal propensities may be caused by different strategies in response to environmental cues inducing dispersal, such as reproductive success. In such cases, the reported differences between immigrants and philopatric individuals may not reflect true variation in survival. We studied whether dispersal status specific apparent adult survival is associated with reproductive success in a Temminck's stint Calidris temminckii population. We analysed two long term capture–recapture datasets characterised by low and high nest predation levels. Philopatric individuals had higher apparent adult survival than immigrants in both datasets and the difference was highlighted during the high nest predation period. By contrasting return rates between successful and unsuccessful breeders as a proxy for dispersal, we found that unsuccessful immigrants breeding for the first time dispersed more likely than successful immigrants, but such a pattern was not found among philopatric individuals. Our results support the hypothesis that immigrant and philopatric individuals have different breeding dispersal strategies following reproductive failure and that their apparent adult survival differences are at least partly explained by different breeding dispersal propensities. Our results also suggest that the recent decline of the study population reflects a multiple response to increased nest predation through decreased local recruitment and increased emigration.     

Philopatry and within-colony movements in Columbian ground squirrels

Philopatry and dispersal result in selection of habitat locations that may differ in resources and social environment and thus should influence fitness components like survival and reproduction. We examined short-distance movements of young and adult females from natal or previous nesting sites within a colony of Columbian ground squirrels (Urocitellus columbianus) in the Rocky Mountains of Alberta, Canada, over a 17-year period. Females of all ages were strongly philopatric, yet a few (10-15%) exhibited movements that took them to new home ranges. We tested three hypotheses to explain the pattern of female natal and breeding movements: (1) that movements of philopatric females promote proximity to close kin; (2) that range shifts favour close kin via bequeathal of territory and (3) that dispersers move to lower density areas where competition for resources is lower. Tests of these three hypotheses revealed that: (1) philopatry and movements of young and older philopatric females led to proximity to mothers and local presence of close kin; (2) breeding dispersal did not result in bequeathal of home range to daughters, but movements of philopatric females suggested that they shared space with close kin and (3) adult females moved to new ranges with lower local densities, though dispersing females also left ranges where local density was significantly lower than for philopatric females. Natal and breeding movements among years produced two opportunities for territorial females: close spatial proximity to close kin via short philopatric movements, and habitats with fewer competitors via longer dispersal movements.     

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio) that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.     

Reduced habitat quality increases intrinsic but not ecological costs of reproduction

Although the costs of reproduction are predicted to vary with the quality of the breeding habitat thereby affecting population dynamics and life‐history trade‐offs, empirical evidence for this pattern remains sparse and equivocal. Costs of reproduction can operate through immediate ecological mechanisms or through delayed intrinsic mechanisms. Ignoring these separate pathways might hinder the identification of costs and the understanding of their consequences. We experimentally investigated the survival costs of reproduction for adult little owls (Athene noctua) within a gradient of habitat quality. We supplemented food to nestlings, thereby relieving the parents’ effort for brood provisioning. We used radio‐tracking and Bayesian multistate modeling based on marked recapture and dead recovery to estimate survival rates of adult little owls across the year as a function of food supplementation and habitat characteristics. Food supplementation to nestlings during the breeding season increased parental survival not only during the breeding season but also during the rest of the year. Thus, the low survival of parents of unfed broods likely represents both, strong ecological and strong intrinsic costs of reproduction. However, while immediate ecological costs occurred also in high‐quality habitats, intrinsic costs carrying over to the post‐breeding period occurred only in low‐quality habitats. Our results suggest that immediate costs resulting from ecological mechanisms such as predation, are high also in territories of high habitat quality. Long‐term costs resulting from intrinsic trade‐offs, however, are only paid in low‐quality habitats. Consequently, differential effects of habitat quality on immediate ecological and delayed intrinsic mechanisms can mask the increase of costs of reproduction in low‐quality breeding habitats. Intrinsic costs may represent an underrated mechanism of habitat quality affecting adult survival rate thereby considerably accelerating population decline in degrading habitats. This study therefore highlights the need for a long‐term perspective to fully assess the costs of reproduction and the role of habitat quality in modifying these costs.     

Habitat-specific clutch size and cost of incubation in eiders reconsidered

The energetic incubation constraint hypothesis (EICH) for clutch size states that birds breeding in poor habitat may free up resources for future reproduction by laying a smaller clutch. The eider (Somateria mollissima) is considered a candidate for supporting this hypothesis. Clutch size is smaller in exposed nests, presumably because of faster heat loss and higher incubation cost, and, hence, smaller optimal clutch size. However, an alternative explanation is partial predation: the first egg(s) are left unattended and vulnerable to predation, which may disproportionately affect exposed nests, so clutch size may be underestimated. We experimentally investigated whether predation on first-laid eggs in eiders depends on nest cover. We then re-evaluated how nesting habitat affects clutch size and incubation costs based on long-term data, accounting for confounding effects between habitat and individual quality. We also experimentally assessed adult survival costs of nesting in sheltered nests. The risk of egg predation in experimental nests decreased with cover. Confounding between individual and habitat quality is unlikely, as clutch size was also smaller in open nests within individuals, and early and late breeders had similar nest cover characteristics. A trade-off between clutch and female safety may explain nest cover variation, as the risk of female capture by us, mimicking predation on adults, increased with nest cover. Nest habitat had no effect on female hatching weight or weight loss, while lower temperature during incubation had an unanticipated positive relationship with hatching weight. There were no indications of elevated costs of incubating larger clutches, while clutch size and colony size were positively correlated, a pattern not predicted by the ‘energetic incubation constraint’ hypothesis. Differential partial clutch predation thus offers the more parsimonious explanation for clutch size variation among habitats in eiders, highlighting the need for caution when analysing fecundity and associated life-history parameters when habitat-specific rates of clutch predation occur.     

Habitat-specific clutch size and cost of incubation in common eiders, Somateria mollissima

Common eiders, Somateria mollissima, breed on two types of island in the Northern Baltic: open, sparsely vegetated islands and wooded islands with dense mixed forests. On open islands 79.8% of the nests were on open cliffs, exposed to wind and rain whereas on wooded islands 91.7% of the nests were sheltered inside dense spruce and pine thickets. We found that clutch size on open islands was significantly smaller than on wooded islands. Females started breeding simultaneously in the two habitats and they were similar in body size as measured by the length of the radio-ulna. During incubation females on open islands lost weight at a faster rate than females on wooded islands (34 g/day and 19 g/day, respectively). Heat loss is faster on open than wooded islands and therefore we suggest that the faster weight loss of females on open islands result from thermodynamically adverse incubation conditions. Because the eider is an extreme capital breeder, energy used for egg production cannot be used for incubation. To sustain a higher incubation cost on open islands, the optimal clutch size is therefore lower than on wooded islands. Received: 27 January 1997 / Accepted: 14 March 1997     

Landscape and habitat affect frequency of artificial duck nest predation by native species,but not by an alien predator

Annual Finnish breeding duck surveys over the last 30 years show declining abundance among several species and greater declines on eutrophic waters than oligotrophic lakes. It has been suggested that habitat-related differences in the rate of increase in predation pressure is a potential explanation for contrasting duck population trajectories between habitats. We assessed potential duck nest predation risk and predator presence in various duck breeding habitats in Finland and Denmark by monitoring 333 artificial duck nests with wildlife cameras during 2017–2019. Predation rates differed between landscapes and habitats: nest predation rate and predator diversity were lowest in forested and highest in agricultural landscapes. Forest nests further from water bodies survived better than nests around shorelines of permanent lakes. Of the 16 different predator species detected, the most common were Eurasian magpie (Picapica), hooded crow (Corvus corone) and raccoon dog (Nyctereutes procyonoides). While predation by specific native predator species was typically associated with particular habitats and landscapes, the alien raccoon dog appeared to be a true habitat generalist, ubiquitous and common across all habitats and landscapes. Based on these results, the higher duck nest predation pressure along shorelines, especially in agricultural landscape lakes, due to increased diversity and abundance within the predator community, may contribute to the declining population trends of ducks.     

An ‘ecological trap’ for yellow warbler nest microhabitat selection

Contrary to assumptions of habitat selection theory, field studies frequently detect ‘ecological traps’, where animals prefer habitats conferring lower fitness than available alternatives. Evidence for traps includes cases where birds prefer breeding habitats associated with relatively high nest predation rates despite the importance of nest survival to avian fitness. Because birds select breeding habitat at multiple spatial scales, the processes underlying traps for birds are likely scale‐dependent. We studied a potential ecological trap for a population of yellow warblers Dendroica petechia while paying specific attention to spatial scale. We quantified nest microhabitat preference by comparing nest‐ versus random‐site microhabitat structure and related preferred microhabitat features with nest survival. Over a nine‐year study period and three study sites, we found a consistently negative relationship between preferred microhabitat patches and nest survival rates. Data from experimental nests described a similar relationship, corroborating the apparent positive relationship between preferred microhabitat and nest predation. As do other songbirds, yellow warblers select breeding habitat in at least two steps at two spatial scales; (1) they select territories at a coarser spatial scale and (2) nest microhabitats at a finer scale from within individual territories. By comparing nest versus random sites within territories, we showed that maladaptive nest microhabitat preferences arose during within‐territory nest site selection (step 2). Furthermore, nest predation rates varied at a fine enough scale to provide individual yellow warblers with lower‐predation alternatives to preferred microhabitats. Given these results, tradeoffs between nest survival and other fitness components are unlikely since fitness components other than nest survival are probably more relevant to territory‐scale habitat selection. Instead, exchanges of individuals among populations facing different predation regimes, the recent proliferation of the parasitic brown‐headed cowbird Molothrus ater, and/or anthropogenic changes to riparian vegetation structure are more likely explanations.     

Adult survival and reproductive rate are linked to habitat preference in territorial,year‐round resident Song Sparrows Melospiza melodia

Individual animal fitness can be strongly influenced by the ability to recognize habitat features which may be beneficial. Many studies focus on the effects of habitat on annual reproductive rate, even though adult survival is typically a greater influence on fitness and population growth in vertebrate species with intermediate to long lifespans. Understanding the effects of preferred habitat on individuals over the annual cycle is therefore necessary to predict its influences on individual fitness. This is particularly true in species that are resident and territorial year‐round in the temperate zone, which may face potential trade‐offs between habitat that maximizes reproduction and that which maximizes non‐breeding season (‘over‐winter’) survival. We used a 37‐year study of Song Sparrows Melospiza melodia residing territorially year‐round on a small island to examine what habitat features influenced adult over‐winter survival, how site‐specific variation in adult survival vs. annual reproductive rate influenced long‐term habitat preference, and if preferred sites on average conferred higher individual fitness. Habitat features such as area of shrub cover and exposure to intertidal coastline predicted adult over‐winter survival independent of individual age or sex, population size, or winter weather. Long‐term habitat preference (measured as occupation rate) was better predicted by site‐specific annual reproductive rate than by expected over‐winter survival, but preferred sites maximized fitness on average over the entire annual cycle,. Although adult over‐winter survival had a greater influence on population growth (λ) than did reproductive rate, the influence of reproductive rate on λ increased in preferred sites because site‐specific variation in reproductive rate was higher than variation in expected over‐winter survival. Because preferred habitats tended to have higher mean site‐specific reproductive and adult survival rates, territorial birds in this population do not appear to experience seasonal trade‐offs in preferred habitat but are predicted to incur substantial fitness costs of settling in less‐preferred sites.     

Direct and indirect effects of predation on mosquitofish behavior and survival

Predation can have strong direct and indirect effects on the behavior of prey. We investigated whether predation by chain pickerel (Esox niger) caused adult eastern mosquitofish (Gambusia holbrooki) to alter their habitat use and whether pickerel predation influenced survival of adult and neonate mosquitofish. The number of adult mosquitofish using the riskier of three habitats was lowest when two predators occupied the risky habitat, intermediate in the treatment with one predator, and highest when no predators occurred there. More mosquitofish neonates survived high predation treatments than treatments lacking pickerel. We conclude that pickerel predation causes adult mosquitofish to shift to refuge habitats. The pattern of neonate survival suggests that adult habitat use may create a refuge from cannibalism for neonate mosquitofish, resulting in higher neonate survival in treatments with more pickerel. Hence, pickerel predation has a direct effect on adult mosquitofish behavior and a strong indirect effect on neonate survival. Both interspecific and intraspecific predation can effect prey populations and can interact to produce important indirect effects.     

Snow evens fragmentation effects and food determines overwintering success in ground-dwelling voles

Climate instability strongly affects overwintering conditions in organisms living in a strongly seasonal environment and consequently their survival and population dynamics. Food, predation and density effects are also strong during winter, but the effect of fragmentation of ground vegetation on ground-dwelling small mammals is unknown. Here, we report the results of a winter experiment on the effects of habitat fragmentation and food on experimental overwintering populations of bank voles Myodes glareolus. The study was conducted in large outdoor enclosures containing one large, two medium-sized or four small habitat patches or the total enclosure area covered with protective tall-grass habitat. During the stable snow cover of midwinter, only food affected the overwintering success, body condition, trappability and earlier onset of breeding in bank voles. However, after the snow thaw in spring, habitat fragmentation gained importance again, and breeding activities increased the movements of voles in the most fragmented habitat. The use of an open, risky matrix area increased along the habitat fragmentation. Our experiment showed that long-lasting stable snow cover protects overwintering individuals in otherwise exposed and risky ground habitats. We conclude that a stable winter climate and snow cover should even out habitat fragmentation effects on small mammals. However, along prolonged snow-free early winter and in an earlier spring thaw, this means loss of protection by snow cover both in terms of thermoregulation and predation. Thus, habitat cover is important for the survival of small ground-dwelling boreal mammals also during the non-breeding season.     

Demography of fluctuating prairie vole populations: comparison of demographic variables among phases of fluctuations

We tested for differences in the proportion of reproductively active males and females, proportion of the population composed of young and immigrants, and monthly survival (total, adult, young) among phases (trough, increase, and decline) and among habitats (alfalfa, bluegrass, and tallgrass) of 30 population fluctuations ofMicrotus ochrogaster Wagner, 1842 over 25 years in east-central Illinois USA. Total population survival and survival of adults and young were greatest during the increase phase, among fluctuations, irrespective of habitat. The proportion of reproductively active adult males and females was lowest during the decline phase, an effect of lower reproduction during the winter. These results suggest that phase-specific changes in survival were the primary demographic factor driving population fluctuations ofM. ochrogaster in our study sites. We conclude that small-scale spatially different population fluctuations may be explained by the same mechanisms that explain fluctuations within a population.     

Nest-predation at the edge: an experimental study contrasting two types of edges in the dry Chaco, Paraguay

Forest fragmentation leads to the creation of isolated forest patches with subsequent impact on forest-interior flora and fauna. Forested corridors have been suggested to alleviate some of the impact by increasing the connectivity between remnant forest patches. However, both fragmentation and corridors increase the ratio of edge to core habitat. We studied nest predation of artificial nests at edges between I) contiguous forests and pastures and 2) forested corridors and pastures, in a forest-dominated landscape in the dry Chaco, Paraguay, The aim was lo determine if nest predation was higher near habitat edges compared to within forests and pastures, with special emphasis on edges at forested corridors. We found that predation rates were similar at edges and in interior habitats. Nest predation was higher for both ground and shrub nests in forested areas than in pastures, Predation rates were also higher for both ground and shrub nests at edges along forested corridors compared to edges neighbouring contiguous forests. Forested corridors connecting contiguous forests may thus act as an ecological sink for some species breeding here. Analysis of predator categories revealed that ground nests in pastures were relatively more depredated by mammals and less by birds, compared to both shrub nests in pastures and ground nests in forests.     

Diagnosing the environmental causes of the decline in Grey Partridge Perdix perdix survival in France

We studied Grey Partridge Perdix perdix mortality during breeding to identify the environmental causes of a long‐term decline in adult survival. We radiotagged and monitored daily from mid‐March to mid‐September 1009 females on ten contrasting study sites in 1995‐97. Simultaneously, we recorded habitat features and estimated the abundance of Hen and Marsh Harriers Circus cyaneus and C. aeruginosus Red Fox Vulpes vulpes and mustelids. We experimentally tested whether scavenging could have biased predation rates. We also examined, through the necropsy of 80 carcasses of Grey Partridge, whether disease, parasites or poisoning could have been ultimate causes of high predation rates. The survival rate of radiotagged females during spring and summer ranged from 0.25 to 0.65 across study areas. Mortality peaked in May, June and July when females were laying and incubating. The direct negative impact of farming practices was low (6%). Predation was the main proximate cause of female mortality during breeding (73%) and determined the survival rate, suggesting no compensation by other causes of mortality. Ground carnivores were responsible for 64% of predation cases, and raptors for 29%, but this proportion varied across study sites. Disease and poisoning did not appear to favour predation, and scavenging was not likely to have substantially overestimated predation rates. The predation rate on breeding females was positively correlated with the abundance of Hen and Marsh Harriers, suggesting an additional mortality in areas where harriers were abundant. The proportion of raptor predation was linearly related to harrier abundance. The predation rate was not correlated with the abundance of the Red Fox and mustelids. A potential density‐dependent effect on the predation rate was confounded by the abundance of harriers. We found no convincing relationship between the predation rate and habitat features, but we observed a positive relationship between the abundance of Hen and Marsh Harriers and the mean field size. This suggested that habitat characteristics may contribute to high predation rates through predator abundance or habitat‐dependent predation.     

How Does Chytrid Infection Vary Among Habitats? The Case of Litoria wilcoxii (Anura, Hylidae) in SE Queensland, Australia

Most analyses dealing with the geographical distribution of the chytrid fungus (Batrachochytrium dendrobatidis) have been performed on large geographical scales and data on more localized distribution of the chytrid within catchments are scarce. In this study, we compare the prevalence and intensity of infection of chytrid within and outside rainforest habitats at five independent catchments in southeast Queensland. In each catchment, we sampled adult Litoria wilcoxii along two transects on the same stream: one in forested areas, and the other in open nearby farmland. We analyzed swabs using quantitative PCR techniques. Male frogs were in higher densities in open habitats compared with the nearby forested areas. Infected male frogs were found in all catchments surveyed; however, prevalence of B. dendrobatidis in adult males was higher in the forested habitats than in the open habitats in four of the catchments. There was no significant difference in intensity of infection between forested and open habitats. For adult females and juveniles, sample sizes were not high enough for comparisons. Our results suggest that habitat influences chytrid prevalence and open areas may provide refuge from chytrid-induced population declines.     

Lagged effects of North Atlantic Oscillation on spittlebug Philaenus spumarius (Homoptera) abundance and survival

The North Atlantic Oscillation (NAO) is a large‐scale pattern of climate variability that has been shown to have important ecological effects on a wide spectrum of taxa. Studies on terrestrial invertebrates are, however, lacking. We studied climate‐connected causes of changes in population sizes in island populations of the spittlebug Philaenus spumarius (L.) (Homoptera). Three populations living in meadows on small Baltic Sea islands were investigated during the years 1970–2005 in Tvärminne archipelago, southern Finland. A separate analysis was done on the effects of NAO and local climate variables on spittlebug survival in 1969–1978, for which survival data existed for two islands. We studied survival at two stages of the life cycle: growth rate from females to next year's instars (probably mostly related to overwintering egg survival), and survival from third instar stage to adult. The latter is connected to mortality caused by desiccation of plants and spittle masses. Higher winter NAO values were consistently associated with smaller population sizes on all three islands. Local climate variables entering the most parsimonious autoregressive models of population abundance were April and May mean temperature, May precipitation, an index of May humidity, and mean temperature of the coldest month of the previous winter. High winter NAO values had a clear negative effect on late instar survival in 1969–1978. Even May–June humidity and mean temperature of the coldest month were associated with late instar survival. The climate variables studied (including NAO) had no effect on the growth rate from females to next year's instars. NAO probably affected the populations primarily in late spring. Cold and snowy winters contribute to later snow melt and greater spring humidity in the meadows. We show that winter NAO has a considerable lagged effect on April and May temperature; even this second lagged effect contributes to differences in humidity. The lagged effect of the winter NAO to spring temperatures covers a large area in northern Europe and has been relatively stationary for 100 years at least in the Baltic area.     

Habitat-mediated impact of alien mink predation on common frog densities in the outer archipelago of the Baltic Sea

Alien predators have been recognised as one possible cause for amphibian declines around the world, but little is known of habitat-mediated predation impacts especially on adult amphibians. We studied common frog Rana temporaria under American mink Mustela vison predation in the outer archipelago of the Baltic Sea, south-western Finland. Using egg batches as an index of breeding frog female numbers we compared frog numbers and densities between a large, long-term mink-removal area and a comparable control area. Frog numbers in the removal area were at least 2.7-fold higher than those in the control area. In the presence of mink, frog densities increased with the amount of vegetation cover on the islands, indicating that mink predation affected frog densities especially on less-vegetated islands. An opposite trend appeared to be true for frogs in the mink-removal area, where other predators like snakes could induce a decline of frog densities on more vegetated islands. Shrub or grass vegetation seems to provide frogs shelter against alien mink predation. Our result highlights the importance of landscape-level habitat management as a conservation tool for amphibian populations.     

Spatial explicit demography: The effects habitat patch isolation have on vole matrilines

Populations of many species are spatially structured in matrilines, and their dynamics may be determined by matriline specific demographic processes. We examined whether the isolation of habitat patches (i.e. interpatch distance) affected the demography of matrilines in 14 experimentally fragmented populations of the root vole. Matrilines inhabiting the most isolated patches decreased in size over the breeding season, while matrilines in less isolated patches increased. The survival rate of adult females was the main factor underlying the variation in growth rates among matrilines. Low survival when patches were isolated seemed to be due to long-distance interpatch movements exposing females to increased predation rate.
The differential success of matrilines in patchy populations with variable interpatch distances acted to decrease the matrilineal diversity at the population level. Furthermore, isolated patches may function as sinks. Thus spatially explicit landscape features may affect both population demography and genetics.     

Multiscale Habitat Use by Wolverines in British Columbia,Canada

ABSTRACT Wolverine (Gulo gulo) distribution in British Columbia, Canada, includes multiple-use lands where human use and resource extraction may influence habitat selection. We evaluated seasonal habitat use by resident adult wolverines using radiotelemetry locations from 2 multiple-use landscapes in British Columbia. Food, predation risk, and human disturbance hypotheses were considered in logistic regression analyses of used and random landscapes. Male wolverine habitat associations were most supported by the food hypothesis in both summer and winter. Moose (Alces alces) winter ranges, valley bottom forests, and avalanche terrain were positively associated with winter male wolverine use. Habitat use by male wolverines in winter was also negatively associated with helicopter skiing areas in the Columbia Mountains. Habitat associations of females were more complex; combinations of variables supporting food, predation risk, or human disturbance hypotheses were included in most supported models from both summer and winter in both study areas. Females were associated with alpine and avalanche environments where hoary marmot (Marmota caligata) and Columbia ground squirrel (Spermophilus columbianus) prey are found in summer. Roaded and recently logged areas were negatively associated with female wolverines in summer. In the Columbia Mountains, where winter recreation was widespread, females were negatively associated with helicopter and backcountry skiing. Moose winter ranges within rugged landscapes were positively associated with females during winter. Our analysis suggests wolverines were negatively responding to human disturbance within occupied habitat. The population consequences of these functional habitat relationships will require additional focused research. Our spatially explicit models can be used to support conservation planning for resource extraction and tourism industries operating in landscapes occupied by wolverines.