Robert K Swihart

Robert K Swihart
Purdue University | Purdue · Department of Forestry and Natural Resources

PhD

About

226
Publications
29,828
Reads
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9,422
Citations

Publications

Publications (226)
Article
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Context Maximum clique analysis (MCA) can approximate landscape carrying capacity (Nk) for populations of territorial wildlife. However, MCA has not been widely adopted for wildlife applications, mainly due to computational constraints and software wildlife biologists may find difficult to use. Moreover, MCA does not incorporate uncertainty into es...
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Wildlife agencies in North America desire to incorporate broader public interests into decision-making so they can realize the principle of governing wildlife in the public trust. Public satisfaction is a key component of good governance but evaluating satisfaction with wildlife management focuses on traditional user experiences rather than percept...
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Understanding habitat selection of top predators is critical to predict their impacts on ecological communities and interactions with humans, particularly in recovering populations. We analyzed habitat selection in a recovering population of bobcats ( Lynx rufus ) in south-central Indiana using a Random Forest model. We predicted that bobcats would...
Article
Effective wildlife management often relies on estimates of animal density, and cue counting is a viable estimation strategy. A key component of density estimation from dung, a form of cue counting, is estimation of the persistence time, t^ $\hat{t}$, of dung piles. However, differences between observers on what constitutes a dung pile may alter sub...
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Timber harvesting can have strong effects on terrestrial salamanders, which are critical components of forest ecosystems and indicators of environmental change. Effects of harvest methods such as clearcutting have been studied in the short term, but few studies have examined salamander trends throughout the decade following timber harvest. The effe...
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Habitat fragmentation and degradation have led to a proliferation of small and isolated populations that are vulnerable to genetic erosion. Reduction in habitat and concomitant declines in population connectivity can expediate the collapse of species that exist as natural metapopulations. In recent years, Allegheny woodrats (Neotoma magister) have...
Article
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The populations of many species of raptors that forage in agroecosystems have declined as agriculture has intensified. Cover crops are a recent trend in areas of intensive row-crop agriculture in the Midwestern United States that could positively affect raptors by increasing the abundance and distribution of raptor prey. We assessed the habitat use...
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Camera trapping is an effective non-invasive method for collecting data on wildlife species to address questions of ecological and conservation interest. We reviewed 2,167 camera trap (CT) articles from 1994 to 2020. Through the lens of technological diffusion, we assessed trends in: (1) CT adoption measured by published research output, (2) topic,...
Article
Volunteer corn arising from unharvested kernels in fields is a common problem that reduces yield of crops like soybean in intensive rotational agricultural systems. Over the last decade, farmers in the Midwestern United States have increased use of cover crops to improve soil health and suppress weeds in corn‐soybean rotational agriculture. We asse...
Article
Across the Midwestern United States, farmers have increasingly used winter cover crops in corn–soybean rotations to improve soil health. Although this practice has many benefits, it also can provide habitat for potential pest species, such as voles (Microtus pennsylvanicus and M. ochrogaster). Voles have been reported by farmers to damage soybean p...
Article
Bobcat (Lynx rufus) populations have increased in the midwestern U.S. since the 1980s after substantial declines and local extirpations into the mid-1900s. We monitored 38 radio-collared bobcats (25 males, 13 females) from 1998 to 2006 in a recovering population in south-central Indiana to investigate survival and mortality causes. Annual survival...
Article
Increased use of cover crops to promote soil health in high-intensity row-crop agroecosystems has resulted in more frequent reports of damage to soybean (Glycine max) commodity crops by voles (Microtus). Meadow (M. pennsylvanicus) and prairie voles (M. ochrogaster) may use overhead cover and forage provided by cover crops and browse soybean seedlin...
Article
Cover crops are an increasingly common conservation practice in intensive row‐crop agriculture of the Midwestern United States and can improve wildlife habitat. However, they also benefit agricultural pest species such as voles (Microtus ), which have damaged cover‐cropped soybean fields in Indiana. We tested the feasibility of attracting raptors,...
Article
Use of cover crops in intensive row-crop agriculture has dramatically increased over the last decade. Cover crops provide vegetative cover and forage that may support more diverse and abundant rodent communities than those found in conventional row-crop agroecosystems. However, increasing vole populations can lead to depredation of the soybean (Gly...
Article
Understanding how habitat loss and fragmentation impact genetic variation is a major goal in landscape genetics, but to date, most studies have focused solely on the correlation between intervening matrix and genetic differentiation at a single spatial scale. Several caveats exist in these study designs, among them is the inability to include measu...
Article
Delineation of management units for harvested wildlife should strive to maximize homogeneity within each unit subject to constraints imposed by geography and heterogeneity in factors related to human‐caused changes in vital rates. Prior efforts to delineate management units for white‐tailed deer (Odocoileus virginianus) used regression to identify...
Article
The mechanism underlying detection of seed dormancy by scatter‐hoarding rodents is unclear, although previous work suggests that the pericarp plays an important role in signaling dormancy status. Eastern gray squirrels (Sciurus carolinensis) consume early germinating seeds as they are more likely to perish immediately, whereas dormant seeds tend to...
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Wildlife species differ in their resistance to landscape modifications including habitat loss and fragmentation. We hypothesized that niche breadth is positively related to both (1) overall species occurrence and (2) species response to landscape modification, because species with a wide range of diet and/or habitat preferences should be able to co...
Article
Many small mammal populations respond quickly to timber harvest aimed at oak (Quercus) regeneration, which alters microhabitat. We used mark-release–recapture data collected 6–8 years postharvest from the Hardwood Ecosystem Experiment in southern Indiana, United States, to model density and apparent survival of eastern chipmunks (Tamias striatus) a...
Article
In eastern North America, oak (Quercus) regeneration failure has spurred management using silvicultural approaches better aligned with the autecology of oaks. In particular, shelterwood harvests can create favorable intermediate light conditions for oak establishment, and prescribed fire is predicted (by the oak‐fire hypothesis) to favor oak regene...
Article
Ecological complexity may improve ecosystem function, stability and adaptability to natural and anthropogenic disturbances. Intraspecific trophic variation can represent a significant component of total community variation and can influence food web structure and function. Thus, understanding how trophic niches are partitioned between intraspecific...
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1. Habitat loss and fragmentation often leads to defaunation of large-bodied mammals , and their loss could trigger release from top-down control or food resource competition for small mammal seed dispersers, which in turn may affect the effectiveness of seed dispersal by altering the number of dispersed seeds or the manner in which they are disper...
Article
Scatter-hoarding rodents such as tree squirrels selectively cache seeds for subsequent use in widely-spaced caches placed below the ground surface. This behavior has important implications for seed dispersal, seedling establishment, and tree regeneration. Hoarders manage these caches by recovering and eating some seeds, and moving and re-caching ot...
Article
Declining populations of forest songbirds in the eastern U.S. have emphasized a need for scientists and managers to understand habitat selection by birds in remnant patches of contiguous forest. Past work has identified effects of landscape-scale covariates on bird occurrence and abundance; however, less is known about the effects of local-scale fo...
Article
Measures of scholarly performance have proliferated, without corresponding efforts to standardize comparisons among faculty. An exception was a recent use of regression to model sources of variation in scholarly performance by fisheries and wildlife faculty. We applied this model-based method to data for 404 forestry and forest products faculty fro...
Article
Ecologists often focus on summarized composition when assessing complex, multivariate phenotypes such as fatty acids. Increasing complexity in fatty acid composition may offer benefits to individuals that may not be recognized by assessing mean fatty acid identity. We quantified fatty acid identity and complexity in the egg and muscle of spawning f...
Article
The influence of forest fragmentation and associated habitat edges differentially affects forest-dependent organisms, particularly when certain species are able to use resources from surrounding matrix habitats. The white-footed mouse is a forest habitat generalist and is known to disperse among adjoining farmland habitats, including agricultural m...
Article
The Worm-eating Warbler (Helmitheros vermivorum) is typically described as a mature forest species requiring moderate to steep slopes and dense understory vegetation for breeding. However, nesting microhabitat characteristics vary regionally. Given the extensive variation in landscape topography, forest composition, and habitat structure across the...
Article
ABSTRAC Submandibular venipuncture is a common technique used to harvest whole blood from laboratory‐strain mice, but its effectiveness on wild‐caught Peromyscus spp. has not been formally tested. We used submandibular venipuncture to collect repeated blood samples from 30 wild‐caught deer mice (Peromyscus maniculatus) and white‐footed mice (P. leu...
Article
Seeds of many hardwood trees are dispersed by scatter-hoarding rodents, and this process is often mediated by the traits of seeds. Although numerous studies have linked seed traits to seed preference by rodents, little is known about how rodents forage for seeds when multiple desirable and undesirable seed traits are available simultaneously. Here,...
Article
Prairie deer mice (Peromyscus maniculatus bairdii) are permanent residents of row-crop fields in the Midwestern United Sates, and may provide ecosystem services by regulating weed seed and waste grain populations. Seed predation is especially critical in the months of highest seed availability following crop harvest, and is dictated by population d...
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Comparatively little is known about hantavirus prevalence within rodent populations from the Midwestern US, where two species of native mice, the prairie deer mouse (Peromyscus maniculatus bairdii) and the white-footed mouse (Peromyscus leucopus noveboracensis), are dominant members of rodent communities. We sampled both species in central Indiana...
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Native seed predators, such as mice (Peromyscus spp.) and ground beetles (Carabidae), consume weed seeds and waste grain within agricultural fields and thus provide a potentially important service to farmers. Most previous investigations of agricultural seed predation services have focused on within-field factors that affect rates of seed removal a...
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Early tree life history and demography are driven by interactions with the environment such as seed predation, herbivory, light availability, and drought. For oak (Quercus) in the eastern United States, these interactions may contribute to oak regeneration failure. Numerous studies have examined the impact of individual factors (like seed predation...
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Edge habitats create environmental gradients that affect plant community composition and herbivore behavior. Silvicultural disturbance creates edge habitat with direct (via changes in light) and indirect (via changes in herbivore behavior) consequences for the growth and survival of tree seedlings, and thus, the composition of the future forest sta...
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In tropical America, regeneration of big- leaf mahogany, Swietenia macrophylla King, the most important commercial tree species, is problematic because of its fruiting and dispersal characteristics, very low tolerance of shade and response to logging. In Quintana Roo, Mexico, abandoned slash-and-burn crop elds are excellent candidates for seedling...
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Oak (Quercus) is a dominant component of the overstory in the Central Hardwood Forest region, but is currently failing to regenerate throughout much of its range. Loss of oak as a canopy dominant species would be devastating to the numerous species of wildlife that rely on acorns as a food resource. Intolerance to shade, competitive interactions, a...
Article
O ak (Quercus) is a dominant component of the overstory in the Central Hardwood Fores region but is currently failing to regenerate throughout much of its range. Loss of oak as a canopy dominan species would be devastating to the numerous species of wildlife that rely on acorns as a foo resource Intolerance to shade, competitive interactions, and h...
Article
Seed predation and rodent foraging behaviors depend on frequency of available seeds and seed traits. However, the interaction of frequency of seed availability and seed traits adds a new level of complexity to granivore–seed dynamics. We conducted experiments with eastern gray squirrels (Sciurus carolinensis) designed to elucidate the frequency × t...
Article
Many declining populations of the imperiled Allegheny woodrat (Neotoma magister) function as nonequilibrium metapopulations in which rates of subpopulation extirpation exceed recolonization. Quantifying and maximizing survival rates thus becomes critical for the conservation of these spatially structured populations. We used encounter histories of...
Article
Timber harvests that aim to promote oak (Quercus) regeneration may have indirect impacts on seedling recruitment by altering trophic interactions between oak and animals. For example, changes in habitat structure following harvest may alter the conditionally mutualistic relationship between oak and small mammal granivores like the gray squirrel (Sc...
Article
Allee effects increasingly are recognized as influential determinants of population dynamics, especially in disturbed landscapes. We developed a predator–prey metapopulation model to study the impact of an Allee effect on predator–prey. The model incorporates habitat destruction and predators with imperfect information about prey distribution. Crit...
Article
Consumption of weed seeds and waste grains by seed predators is an important ecosystem service that helps to regulate weed and volunteer crop populations in many agricultural systems. The prairie deer mouse is found in a variety of sparsely vegetated habitats throughout the central United States and is the dominant vertebrate seed predator in row-c...
Data
Table S1. Resistance values of each resistance surface for chipmunks and white footed mice. Table S2. Results from within study cell analyses of Mantel tests and spatial autocorrelations in chipmunks and white‐footed mice. Table S3. Parameter estimates for reduced models for each resistance surface (IBD, IBB, MortL, MortH, MoveL, MoveH) that quan...
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Conversion of formerly continuous native habitats into highly fragmented landscapes can lead to numerous negative demographic and genetic impacts on native taxa that ultimately reduce population viability. In response to concerns over biodiversity loss, numerous investigators have proposed that traits such as body size and ecological specialization...
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Research productivity and impact are often considered in professional evaluations of academics, and performance metrics based on publications and citations increasingly are used in such evaluations. To promote evidence-based and informed use of these metrics, we collected publication and citation data for 437 tenure-track faculty members at 33 rese...
Data
Manual and R (3.0.2) code to perform comparisons and analyses with additional faculty members. (PDF)
Data
Sample database of “new” individuals for inclusion in analysis after re-fitting of models with S1 Code. (CSV)
Data
Average annual normalized citations per article for JCR categories and associated fisheries and wildlife sub-disciplines as grouped in Table 2. Normalization was accomplished by dividing values by the corresponding citations per article for mathematics. (DOCX)
Data
Correlations of standardized deviance residuals from 8 models for faculty in fisheries and wildlife. (DOCX)
Data
Database of 437 faculty used for model-based benchmarking of fisheries and wildlife. (CSV)
Article
Full-text available
Publication- and citation-based metrics are commonly used to summarize the productivity and impact of individuals, institutions, and journals. We examined factors hypothesized to explain variation in 5 author-based performance metrics among 437 fisheries and wildlife faculty from 33 research-extensive universities in the United States. Regression a...
Article
Environmental DNA (eDNA) is DNA that has been isolated from field samples, and it is increasingly used to infer the presence or absence of particular species in an ecosystem. However, the combination of sampling procedures and subsequent molecular amplification of eDNA can lead to spurious results. As such, it is imperative that eDNA studies includ...
Article
Full-text available
In tropical America, regeneration of big leaf mahogany, Swietenia macrophylla King, the most important commercial tree species, is problematic because of its fruiting and dispersal characteristics, very low tolerance of shade and response to logging. In Quintana Roo, Mexico, abandoned slash-and-burn cropfields are excellent candidates for seedling...
Article
A mechanistic understanding of seed movement and survival is important both for the development of theoretical models of plant population dynamics, spatial spread, and community assembly, and for the conservation and management of plant communities under global change. While models of wind-borne seed dispersal have advanced rapidly over the past tw...
Article
Range-wide declines of the Allegheny woodrat (Neotoma magister) have been attributed, in part, to reductions in mast associated with extirpation of American chestnut (Castanea dentata) and transition to oak (Quercus)-dominated forests prone to periodic mast failure. Chestnuts produce mast more consistently than oaks; hence, efforts to restore a bli...
Article
Restoration of the functionally extirpated American chestnut (Castanea dentata) to landscapes of the eastern United States is planned with the successful propagation of a blight-resistant hybrid tree. Predicting the response of rodent seed consumers to this novel source of mast will be critical to restoration success, as rodents are important seed...
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The evolution of specific seed traits in scatter-hoarded tree species often has been attributed to granivore foraging behavior. However, the degree to which foraging investments and seed traits correlate with phylogenetic relationships among trees remains unexplored. We presented seeds of 23 different hardwood tree species (families Betulaceae, Fag...
Article
Responses of resident owls to changes in forest structure associated with forest management in the Central Hardwood Forest Region of the United States have not been widely studied. We estimated the winter occupancy of Barred Owls (Strix varia) and Eastern Screech-Owls (Megascops asio) in forests with varying levels of timber harvest in southern Ind...
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Baylisascaris procyonis is a common gastrointestinal parasite of raccoons (Procyon lotor) and is a zoonotic helminth with the potential to cause severe or fatal infection. Raccoons thrive in human-dominated landscapes, and the fecal-oral transmission pathway and lack of effective treatment make B. procyonis a serious threat to public health. The di...
Article
The successful development of early stages of blight-resistant hybrid stock has increased hopes for restoration of American chestnut (Castanea dentata) to eastern North American forests. However, these forests have undergone substantial ecological change in the century since the functional extirpation of American chestnut, and it remains unknown to...
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Recent field trials on blight-resistant hybrids (BC3F3) of American chestnut (Castanea dentata) and Chinese chestnut (C. mollissima) have intensified planning for widespread restoration of Castanea to eastern U.S. forests. Restoration will likely rely on natural seed dispersal from sites planted with chestnut; however, we do not know how dispersal...
Article
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Human-altered environments often challenge native species with a complex spatial distribution of resources. Hostile landscape features can inhibit animal movement (i.e., genetic exchange), while other landscape attributes facilitate gene flow. The genetic attributes of organisms inhabiting such complex environments can reveal the legacy of their mo...
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Medicinal baits are distributed to manage zoonotic diseases, including raccoon (Procyon lotor) rabies, but efficient distribution strategies are needed for suburban environments. We developed an automated dispenser that transfers fishmeal polymer baits at user-specified intervals from a magazine to a receptacle fitted with a filter that exploits ra...
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We tested whether community structure of insect seed predators is influenced by spatiotemporal variation in mast availability on host-tree species. Specifically, mast production and acorn weevil (Curculio L., 1758) occupancy were estimated annually from 2006 to 2008 for individual host trees in a sample of 74 northern red oaks (Quercus rubra L.), 1...