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At least 55 records · Page 3Linked to original sources
USGS2014

Habitat structure and body size distributions: Cross-ecosystem comparison for taxa with determinate and indeterminate growth

Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with indeterminate growth has yet to be determined. We provide a cross-ecosystem comparison of bird (determinate growth) and fish (indeterminate growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size–density relationships (SSDRs) and individual size–density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi-modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat–size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross-scale patterns of habitat structure and size for species with determinate growth, such as birds. In contrast, for species with indeterminate growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual-level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.

Oikos↗
USGS2015

A plant toxin mediated mechanism for the lag in snowshoe hare population recovery following cyclic declines

A necessary condition for a snowshoe hare population to cycle is reduced reproduction after the population declines. But the cause of a cyclic snowshoe hare population's reduced reproduction during the low phase of the cycle, when predator density collapses, is not completely understood. We propose that moderate-severe browsing by snowshoe hares upon preferred winter-foods could increase the toxicity of some of the hare's best winter-foods during the following hare low, with the result being a decline in hare nutrition that could reduce hare reproduction. We used a combination of modeling and experiments to explore this hypothesis. Using the shrub birch Betula glandulosa as the plant of interest, the model predicted that browsing by hares during a hare cycle peak, by increasing the toxicity B. glandulosa twigs during the following hare low, could cause a hare population to cycle. The model's assumptions were verified with assays of dammarane triterpenes in segments of B. glandulosa twigs and captive hare feeding experiments conducted in Alaska during February and March 1986. The model's predictions were tested with estimates of hare density and measurements of B. glandulosa twig growth made at Kluane, Yukon from 1988–2008. The empirical tests supported the model's predictions. Thus, we have concluded that a browsing-caused increase in twig toxicity that occurs during the hare cycle's low phase could reduce hare reproduction during the low phase of the hare cycle.

Yukon↗
USGS2016

Local biotic adaptation of trees and shrubs to plant neighbors

Natural selection as a result of plant–plant interactions can lead to local biotic adaptation. This may occur where species frequently interact and compete intensely for resources limiting growth, survival, and reproduction. Selection is demonstrated by comparing a genotype interacting with con- or hetero-specific sympatric neighbor genotypes with a shared site-level history (derived from the same source location), to the same genotype interacting with foreign neighbor genotypes (from different sources). Better genotype performance in sympatric than allopatric neighborhoods provides evidence of local biotic adaptation. This pattern might be explained by selection to avoid competition by shifting resource niches (differentiation) or by interactions benefitting one or more members (facilitation). We tested for local biotic adaptation among two riparian trees, Populus fremontii and Salix gooddingii , and the shrub Salix exigua by transplanting replicated genotypes from multiple source locations to a 17 000 tree common garden with sympatric and allopatric treatments along the Colorado River in California. Three major patterns were observed: 1) across species, 62 of 88 genotypes grew faster with sympatric neighbors than allopatric neighbors; 2) these growth rates, on an individual tree basis, were 44, 15 and 33% higher in sympatric than allopatric treatments for P. fremontii, S. exigua and S. gooddingii , respectively, and; 3) survivorship was higher in sympatric treatments for P. fremontii and S. exigua . These results support the view that fitness of foundation species supporting diverse communities and dominating ecosystem processes is determined by adaptive interactions among multiple plant species with the outcome that performance depends on the genetic identity of plant neighbors. The occurrence of evolution in a plant-community context for trees and shrubs builds on ecological evolutionary research that has demonstrated co-evolution among herbaceous taxa, and evolution of native species during exotic plants invasion, and taken together, refutes the concept that plant communities are always random associations.

Arizona↗
USGS2016

Spatiotemporal patterns of duck nest density and predation risk: a multi-scale analysis of 18 years and more than 10,000 nests

Many avian species are behaviorally-plastic in selecting nest sites, and may shift to new locations or habitats following an unsuccessful breeding attempt. If there is predictable spatial variation in predation risk, the process of many individuals using prior experience to adaptively change nest sites may scale up to create shifting patterns of nest density at a population level. We used 18 years of waterfowl nesting data to assess whether there were areas of consistently high or low predation risk, and whether low-risk areas increased, and high-risk areas decreased in nest density the following year. We created kernel density maps of successful and unsuccessful nests in consecutive years and found no correlation in predation risk and no evidence for adaptive shifts, although nest density was correlated between years. We also examined between-year correlations in nest density and nest success at three smaller spatial scales: individual nesting fields (10–28 ha), 16-ha grid cells and 4-ha grid cells. Here, results were similar across all scales: we found no evidence for year-to-year correlation in nest success but found strong evidence that nest density was correlated between years, and areas of high nest success increased in nest density the following year. Prior research in this system has demonstrated that areas of high nest density have higher nest success, and taken together, our results suggest that ducks may adaptively select nest sites based on the local density of conspecifics, rather than the physical location of last year's nest. In unpredictable environments, current cues, such as the presence of active conspecific nests, may be especially useful in selecting nest sites. The cues birds use to select breeding locations and successfully avoid predators deserve continued attention, especially in systems of conservation concern.

Oikos↗
USGS2017

Animal movement in the absence of predation: environmental drivers of movement strategies in a partial migration system

Animal movement strategies including migration, dispersal, nomadism, and residency are shaped by broad-scale spatial-temporal structuring of the environment, including factors such as the degrees of spatial variation, seasonality and inter-annual predictability. Animal movement strategies, in turn, interact with the characteristics of individuals and the local distribution of resources to determine local patterns of resource selection with complex and poorly understood implications for animal fitness. Here we present a multi-scale investigation of animal movement strategies and resource selection. We consider the degree to which spatial variation, seasonality, and inter-annual predictability in resources drive migration patterns among different taxa and how movement strategies in turn shape local resource selection patterns. We focus on adult Galapagos giant tortoises Chelonoidis spp. as a model system since they display many movement strategies and evolved in the absence of predators of adults. Specifically, our analysis is based on 63 individuals among four taxa tracked on three islands over six years and almost 10 6 tortoise re-locations. Tortoises displayed a continuum of movement strategies from migration to sedentarism that were linked to the spatio-temporal scale and predictability of resource distributions. Movement strategies shaped patterns of resource selection. Specifically, migratory individuals displayed stronger selection toward areas where resources were more predictable among years than did non-migratory individuals, which indicates a selective advantage for migrants in seasonally structured, more predictable environments. Our analytical framework combines large-scale predictions for movement strategies, based on environmental structuring, with finer-scale analysis of space-use. Integrating different organizational levels of analysis provides a deeper understanding of the eco-evolutionary dynamics at play in the emergence and maintenance of migration and the critical role of resource predictability. Our results highlight that assessing the potential benefits of differential behavioral responses first requires an understanding of the interactions among movement strategies, resource selection and individual characteristics.

Oikos↗
USGS2017

Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments

Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore responses across widely varying precipitation conditions in an arid environment. Specifically, we assessed seasonal changes in diet breadth and forage selection of adult female desert bighorn sheep Ovis canadensis mexicana in relation to potential nutritional limitations in forage N, moisture and energy content (as proxied by dry matter digestibility, DMD). Succulents were consistently high in moisture but low in N and grasses were low in N and moisture until the wet period. Nitrogen and moisture content of shrubs and forbs varied among seasons and climatic periods, whereas trees had consistently high N and moderate moisture levels. Shrubs, trees and succulents composed most of the seasonal sheep diets but had little variation in DMD. Across all seasons during drought and during summer with average precipitation, forages selected by sheep were higher in N and moisture than that of available forage. Differences in DMD between sheep diets and available forage were minor. Diet breadth was lowest during drought and increased with precipitation, reflecting a reliance on few key forage species during drought. Overall, forage selection was more strongly associated with N and moisture content than energy content. Our study demonstrates that unlike north-temperate ungulates which are generally reported to be energy-limited, N and moisture may be more nutritionally limiting for desert ungulates than digestible energy.

Arizona↗
USGS2017

Is biotic resistance enhanced by natural variation in diversity?

Theories linking diversity to ecosystem function have been challenged by the widespread observation of more exotic species in more diverse native communities. Few studies have addressed the underlying processes by dissecting how biotic resistance to new invaders may be shaped by the same environmental influences that determine diversity and other community properties. In grasslands with heterogeneous soils, we added invaders and removed competitors to analyze the causes of invasion resistance. Abiotic resistance was measured using invader success in the absence of the resident community. Biotic resistance was measured as the reduction in invader success in the presence of the resident community. Invaders were most successful where biotic resistance was lowest and abiotic resistance was highest, confirming the dominant role of biotic resistance. Contrary to theory, though, biotic resistance was highest where both species richness and functional diversity were lowest. In the multivariate framework of a structural equation model, biotic resistance was independent of community diversity, and was highest where fertile soils led to high community biomass. Seed predation slightly augmented biotic resistance without qualitatively changing the results. Soil-related genotypic variation in the invader also did not affect the results. We conclude that in natural systems, diversity may be correlated with invasibility and yet have little effect on biotic resistance to invasion. More generally, the environmental causes of variation in diversity should be considered when examining the potential functional consequences of diversity.

Oikos↗
USGS2018

Entrapped carrion increases indirect plant resistance and intra‐guild predation on a sticky tarweed

Many plants employ indirect defenses against herbivores; often plants provide a shelter or nutritional resource to predators, increasing predator abundance, and lessening herbivory to the plant. Often, predators on the same plant represent different life stages and different species. In these situations intraguild predation (IGP) may occur and may decrease the efficacy of that defense. Recently, several sticky plants have been found to increase indirect defense by provisioning predatory insects with entrapped insects (hereafter: carrion). We conducted observational studies and feeding trials with herbivores and predators on two sticky, insect‐entrapping asters, Hemizonia congesta and Madia elegans , to construct food webs for these species and determine the prevalence of IGP in these carrion‐provisioning systems. In both systems, intraguild predation was the most common interaction observed. To determine whether IGP was driven by resource abundance, whether it reduced efficacy of this indirect defense and whether stickiness or predator attraction was induced by damage, we performed field manipulations on H. congesta . Carrion supplementation led to an increase in predator abundance and IGP. IGP was asymmetric within the predator guild: assassin bugs and spiders preyed on small stilt bugs but not vice versa. Despite increased IGP, carrion provisions decreased the abundance of the two most common herbivores (a weevil and a mealybug). Overall seed set was driven by plant size, but number of seeds produced per fruit significantly increased with increasing carrion, likely because of the reduction in the density of a seed‐feeding weevil. Observationally and experimentally, we found that carrion‐mediated indirect defense of tarweeds led to much intraguild predation, though predators effectively reduced herbivore abundance despite the increase in IGP.

Oikos↗
USGS2018

Fear of feces? Trade-offs between disease risk and foraging drive animal activity around raccoon latrines

Fear of predation alters prey behavior, which can indirectly alter entire landscapes. A parasite-induced ecology of fear might also exist if animals avoid parasite-contaminated resources when infection costs outweigh foraging benefits. To investigate whether animals avoid parasite contaminated sites, and if such avoidance balances disease costs and foraging gains, we monitored animal behavior at raccoon latrines – sites that concentrate both seeds and pathogenic parasite eggs. Using wildlife cameras, we documented over 40 potentially susceptible vertebrate species in latrines and adjacent habitat. Latrine contact rates reflected background activity, diet preferences and disease risk. Disease-tolerant raccoons and rats displayed significant site attraction, while susceptible birds and small mammals avoided these high-risk sites. This suggests that parasites, like predators, might create a landscape of fear for vulnerable hosts. Such non-consumptive parasite effects could alter disease transmission, population dynamics, and even ecosystem structure.

California↗
USGS2018

Spatially explicit patterns in a dryland's soil respiration and relationships with climate, whole plant photosynthesis and soil fertility

Arid and semiarid ecosystems play a significant role in regulating global carbon cycling, yet our understanding of the controls over the dominant pathways of dryland CO 2 exchange remains poor. Substantial amounts of dryland soil are not covered by vascular plants and this patchiness in cover has important implications for spatial patterns and controls of carbon cycling. Spatial variation in soil respiration has been attributed to variation in soil moisture, temperature, nutrients and rhizodeposition, while seasonal patterns have been attributed to changes in moisture, temperature and photosynthetic inputs belowground. To characterize how controls over respiration vary spatially and temporally in a dryland ecosystem and to concurrently explore multiple potential controls, we estimated whole plant net photosynthesis (A net ) and soil respiration at four distances from the plant base, as well as corresponding fine root biomass and soil carbon and nitrogen pools, four times during a growing season. To determine if the controls vary between different plant functional types for Colorado Plateau species, measurements were made on the C 4 shrub, Atriplex confertifolia , and C 3 grass, Achnatherum hymenoides . Soil respiration declined throughout the growing season and diminished with distance from the plant base, though variations in both were much smaller than expected. The strongest relationship was between soil respiration and soil moisture. Soil respiration was correlated with whole plant A net , although the relationship varied between species and distance from plant base. In the especially dry year of this study we did not observe any consistent correlations between soil respiration and soil carbon or nitrogen pools. Our findings suggest that abiotic factors, especially soil moisture, strongly regulate the response of soil respiration to biotic factors and soil carbon and nitrogen pools in dryland communities and, at least in dry years, may override expected spatial and seasonal patterns.

Oikos↗
USGS2018

Green‐wave surfing increases fat gain in a migratory ungulate

Each spring, migratory herbivores around the world track or ‘surf’ green waves of newly emergent vegetation to distant summer or wet‐season ranges. This foraging tactic may help explain the great abundance of migratory herbivores on many seasonal landscapes. However, the underlying fitness benefits of this life‐history strategy remain poorly understood. A fundamental prediction of the green‐wave hypothesis is that migratory herbivores obtain fitness benefits from surfing waves of newly emergent vegetation more closely than their resident counterparts. Here we evaluate whether this behavior increases body‐fat levels – a critically important correlate of reproduction and survival for most ungulates – in elk Cervus elaphus of the Greater Yellowstone Ecosystem. Using satellite imagery and GPS tracking data, we found evidence that migrants (n = 23) indeed surfed the green wave, occupying sites 12.7 days closer to peak green‐up than residents (n = 16). Importantly, individual variation in surfing may help account for up to 6 kg of variation in autumn body‐fat levels. Our findings point to a pathway for anthropogenic changes to the green wave (e.g. climate change) or migrants’ ability to surf it (e.g. development) to impact migratory populations. To explore this possibility, we evaluated potential population‐level consequences of constrained surfing with a heuristic model. If green‐wave surfing deteriorates by 5–15 days from observed, our model predicts up to a 20% decrease in pregnancy rates, a 2.5% decrease in population growth, and a 30% decrease in abundance over 50 years. By linking green‐wave surfing to fitness and illustrating potential effects on population growth, our study provides new insights into the evolution of migratory behavior and the prospects for the persistence of migratory ungulate populations in a changing world.

Wyoming↗
USGS2020

Asymmetric benefits of a heterospecific breeding association vary with habitat, conspecific abundance and breeding stage

Heterospecific breeding associations may benefit individuals by mitigating predation risk but may also create costs if they increase competition for resources or are more easily detectable by predators. Our understanding of the interactions among hetero‐ and conspecifics is often lacking in mixed species colonies. Here, we test how the presence of hetero‐ and conspecifics influence nest and chick survival for two listed (under the U.S. Endangered Species Act) migratory species breeding on the Missouri River, USA. We monitored 2507 piping plover Charadrius melodus nests and 3245 chicks as well as 1060 least tern Sternula antillarum nests and 1374 chicks on Lake Sakakawea, the Garrison River Reach and the Gavins Point Reach for varying years between 2007 and 2016. Piping plover nest and chick survival improved with the presence and abundance of least terns, but least terns only benefited from piping plover presence for certain study areas and breeding stages. Piping plover nest survival was also improved by the presence and abundance of conspecifics on the Garrison River Reach and was negatively influenced by conspecific presence on Lake Sakakawea. Least tern chick survival improved with the presence of other least terns only on the Gavins Point Reach. Ultimately, the heterospecific breeding association between plovers and terns is mutualistic but asymmetric and is moderated by habitat, abundance of conspecifics and breeding stage. Our results highlight that spatiotemporal variation in the interactions among individuals breeding in groups precludes simple generalizations and suggests that management focused on one species may restrict benefits to that focal species if nest site requirements for heterospecifics are not also included.

Nebraska, North Dakota, South Dakota↗
USGS2020

A latent process model approach to improve the utility of indicator species

The state of an ecosystem is governed by dynamic biotic and abiotic processes, which can only be partially observed. Costs associated with measuring each component limit the feasibility of comprehensive assessments of target ecosystems. Instead, indicator species are recommended as a surrogate index. While this is an attractive concept, indicator species have rarely proven to be an effective tool for monitoring ecosystems and informing management decisions. One deficiency in the existing theoretical development of indicator species may be overcome with the incorporation of latent (i.e. unobservable) states. Advancements in quantitative ecological models allow for latent‐state models to be tested empirically, facilitating the robust evaluation and practical use of indicator species for ecosystem science and management. Here, we extend the existing conceptual models of indicator species to include a direct relationship between an indicator species, ecosystem change drivers and latent processes and variables. Our approach includes explicit consideration of important estimation uncertainty and narrows the range of values a latent variable may take by relating it to measurable attribute(s) of an indicator species. We demonstrate the utility of this approach by relating a commonly cited indicator species, the red‐backed salamander Plethodon cinereus , to a typical latent process of interest – ecosystem health.

Oikos↗
USGS2021

Retreat, detour or advance? Understanding the movements of birds confronting the Gulf of Mexico

During migration, birds must locate stopover habitats that provide sufficient resources to rest and refuel while en route to the breeding or non-breeding area. Long-distance migrants invariably encounter inhospitable geographic features, the edges of which are often characterized by habitat limited in food and safety. In response, they often depart in directions inconsistent with reaching their destination, presumably searching for better habitat. We used automated radio telemetry to track 442 individuals of five species to investigate the behavior of migratory birds as they departed edge habitat along the northern Gulf of Mexico coast during autumn from 2008 to 2014. Most migrants (75%) retreated inland or detoured around rather than advanced across the Gulf, but this depended on bird species and fat-based energy stores. Most individuals in lean condition or of smaller bodied species tended to retreat or detour, rather than advance, when departing from the coast. Twenty-one percent of all birds that departed the coast in 2013–2014 were redetected over 45 km inland, providing a unique opportunity to compare stopover duration, departure times and travel speeds between migrants that retreat away from the coast and those that continue to advance toward their destination. Individuals that retreated the coast and were redetected inland spent ~1 day on the coast before retreating inland, where they spent 11 days before resuming migration. Further when those same individuals retreated from the coast, they departed around evening civil twilight, whereas those that advanced from inland habitats departed after evening civil twilight. Travel speeds were slower for individuals retreating inland compared to those advancing towards the coast from inland habitats. The differences between retreating and advancing individuals suggest how an individual's drive to feed or fly influences behavior. Our study illustrates how the sum of individual decisions can shape habitat use, landscape-scale movements and migration strategies.

Alabama↗
USGS2022

Local diversity in phenological responses of migratory lake sturgeon to warm winters

Rich intraspecific diversity in traits that shape responses to environmental conditions implies that effects of climate change will differ within species or even populations. Nevertheless, few studies investigate how different groups within species respond to climatic fluctuations, and most risk assessments rely upon species-wide generalizations. We studied effects of among-year variation in air temperature on the spring migratory phenology of a metapopulation of lake sturgeon Acipenser fulvescens within waters connecting Lake Huron and Lake Erie of the Laurentian Great Lakes. Sturgeon here express multiple migratory phenotypes that all spawn in either the St. Clair River or Detroit River but differ in their use after spawning of more than 86 000 km 2 of accessible lake and river habitat. Acoustic tracking over nine years (2012–2020) revealed mixed phenological responses to late-winter air temperatures, with three migratory groups arriving at rivers earlier during warm years and one whose arrival was consistent across years regardless of temperature. Notably, two groups that spawn in the same river but overwinter in different lakes entered the river with greater synchrony during warm years because one advanced its phenology while the other did not. The results indicated warm weather could alter the dynamics of the metapopulation and broader community, and exemplify the complexity hidden beneath broadscale generalizations of species' response to climate change.

Michigan, Ontario↗
USGS2022

Geomorphology shapes relationships between animal communities and ecosystem function in large rivers

Understanding how the Earth's surface (i.e. ‘nature's stage') influences connections between biodiversity and ecosystem function (BEF) is a central objective in ecology. Despite recent calls to examine these connections at multiple trophic levels and at more complex and realistic scales, little is known about how landscape structure shapes BEF relationships among animal communities in nature. We coupled high-resolution habitat mapping with extensive field sampling to quantify connections among the geophysical habitat templet, invertebrate assemblages and secondary production in two large North American riverscapes. Patterns of sediment size governed invertebrate assemblage structure, with particularly strong effects on composition, richness and taxonomic and functional diversity. These relationships propagated to drive positive relationships between biodiversity and secondary production that were modified by scale, context-dependencies and anthropogenic modification. Finally, leveraging spatially-explicit descriptions of geophysical and biological properties, we uncovered distinct and nested spatial scales of biodiversity and secondary production, and suggest that multiple geophysical processes simultaneously influence these patterns at different scales. Together, our findings advance our understanding of relationships between the physical templet and patterns of BEF, and help to predict how perturbations to the Earth's surface may propagate to influence biodiversity and energy flux through food webs.

Oikos↗
USGS2023

Timing of reproduction underlies fitness tradeoffs for a salmonid fish

Life history diversity is generated and maintained in part by density-dependent fitness tradeoffs that inhibit a single trait value from reaching fixation. While central to our understanding of evolution, demonstrating density dependence in the strength of fitness tradeoffs is difficult in natural systems. The timing of reproduction is a key life history trait that determines access to breeding habitat and exposure of offspring to competitive interactions and environmental conditions. Understanding the processes underlying diversity in reproductive timing will aid efforts to increase adaptive capacity under global environmental change. Here, we used detailed field studies, genetic parentage assignment, and simulation modeling to evaluate the fitness tradeoffs associated with the timing of reproduction for Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri in groundwater-dominated tributaries to the upper Snake River, Wyoming, USA. We conducted our study across two years to understand how the strength of tradeoffs changes with population density. We found that early breeders experienced reduced reproductive success relative to later breeders due to the negative impact of nest superimposition (where later breeders construct nests overlapping those constructed previously) on embryo survival. However, as the risk of superimposition declined in the low-density year and early breeders experienced fewer losses, reproductive success became more similar among individuals breeding at different times. Further, in the spring following the critical period for growth and survival, offspring of early breeders had experienced longer growing seasons, attained larger body sizes, and were equally abundant relative to those of later breeders, suggesting that fitness losses due to superimposition may be offset by size-dependent competitive ability and overwinter survival. Our results illustrate a mechanism underlying diversity in the timing of reproduction for salmonids. This type of life history diversity will help to ensure the resilience and stability of salmonid populations attempting to adapt to changing local stressors associated with global climate change.

Oikos↗
USGS2024

Intraguild interactions and abiotic conditions mediate occupancy of mammalian carnivores: Co-occurrence of coyotes–fishers–martens

The widespread eradication of large carnivores and subsequent expansion of top mesopredators has the potential to impact species and community interactions with ecosystem-wide implications. An example of these trophic dynamics is the widespread establishment of coyotes following extirpation of wolves and mountain lions in eastern North America. Here, we examined occupancy of three carnivores in northern New York considering both environmental/habitat factors and interspecific interactions. We estimated the co-occurrence of coyotes, fishers, and martens from a landscape-scale winter camera trap survey repeated annually for three years. Martens occurred independently of both coyotes and fishers, while fishers and coyotes displayed positive intraguild interactions that were constant across the landscape. Both marten and fisher first-order occupancy were driven by a combination of biotic and abiotic factors, with both species displaying positive associations with forest cover but antithetical responses to average snow depth. The integral and antithetical role of snow depth in driving the occurrence of martens (positive) and fishers (negative) in the landscape indicates that future climatic warming could reduce the availability of current spatial refuges for martens created by severe winter conditions. Climate-driven alterations to established competitive interactions and co-existence patterns between marten and fisher have critical implications for the species survival and conservation. We provide correlational evidence consistent with the potential for positive top–down effects of dominant mesocarnivores on subordinate species, with fisher occupancy increasing conditional on the presence of coyotes across the landscape. These findings align with the hypothesis that under certain conditions, coyotes may facilitate certain subordinate carnivores. The evidence produced here is consistent with hypotheses on the dynamic nature of trophic niches. We demonstrate the need to consider the interplay between climate, habitat, and interspecific interactions to understand wildlife occupancy patterns and inform wildlife management in a rapidly changing world.

New York↗