Shrub encroachment is altering the structure and species composition of natural communities across the globe. However, little research has focused on how shrub encroachment influences wetland vertebrates, including small mammals. We sought to determine how vegetative structure and shrub cover influenced the occurrence of a threatened semiaquatic mammalian subspecies, the Sanibel Island rice rat (Oryzomys palustris sanibeli). We evaluated the influence of vegetation and metrics of inundation on probability of occurrence and localized seasonal colonization and extinction rates of the Sanibel Island rice rat over a 3-year period. We found Sanibel Island rice rats on 18 (33.3%) of our 54 sites. Their occurrence was positively associated with greater sand cordgrass (Spartina bakeri) cover and increased elevation, but negatively associated with greater shrub cover. Their probability of localized colonization was negatively associated with greater shrub cover. Localized extinction probabilities for Sanibel Island rice rats were positively associated with increased rainfall totals in the preceding 3 months and greater shrub cover. Using aerial photography from across the Sanibel Island rice rat’s range, we found 5.5-fold greater shrub cover in 2015 than in 1944. We suggest that increases in shrub cover and reduced cordgrass cover may be driving the decline of this once ubiquitous endemic species and that the encroachment of freshwater wetlands requires greater attention due to its potential to imperil wetland-dependent wildlife.

ABSTRACTSemi‐aquatic mammals are dependent upon streams and riparian areas, which are a product of the landscapes they drain. Both local stream morphology and surrounding land use are likely to have important influences on current occupancy of semi‐aquatic mammals and potentially affect future geographic distributions. We identified aspects of the riparian system and stream structure at multiple scales that relate to the presence of river otter (Lontra canadensis) and mink (Neovison vison) to better understand how changing landscapes affect occupancy dynamics of these semi‐aquatic mammals and to facilitate future monitoring and management. We estimated multi‐season occupancy using 103 sites sampled over 6 seasonal sampling periods in southern Illinois, USA (44,526 km2) during 2012–2014. We hypothesized river otter and mink occupancy were related to multiple aspects of landscape and local habitat attributes including land cover, water availability, human disturbance, and stream characteristics. Occupancy of river otter was predicted by large stream size, less developed area near the stream site, and proximity to areas with reintroduced or remnant populations of river otter. Mink were more likely to occupy sites with small streams and decreased water availability near the site. However, top models for both species had low weights and high uncertainty for multiple variables. Habitat‐based models may not be the best predictors of occupancy for these carnivores because they are more likely to respond to prey diversity or availability, but landscape changes that decrease natural water availability and increase human disturbance to the stream at the local scale are likely to negatively affect river otter. © 2019 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Predation is one of the main barriers that exotic species may face in newly colonized areas and may help stop or control the potential negative impacts of invasive species in the environment. We evaluated if the consumption of an invasive prey (armored catfish: Pterygoplichtys sp.) affects the dietary niche breadth and trophic level of a native predator (Neotropical river otter: Lontra longicaudis) in northern Guatemala. We examined otter scats from three rivers: two where the invasive armored catfish occurred and one without the invasive fish. Samples were collected two and seven years after the first report of the catfish in the area. We performed gross scat analysis and stable isotope analyses of nitrogen and carbon of fecal matter. Where the invasive armored catfish occurred, it was the main prey item for L. longicaudis. Particularly in the river outside of protected areas seven years after the first report of the catfish, where it accounted for 49% of the otter diet. Concordance was found between the two techniques to estimate dietary niche breadth and trophic level. The dietary niche breath of otters was narrower seven years after the invasion in comparison to two years after the invasion in both invaded rivers, but the extent of the reduction was lesser inside the protected area. Finally, the trophic level of otters also showed a reduction related to the occurrence of the armored catfish in their diet.

Streams and local riparian habitats are a product of the landscapes they drain. Consequently, aspects of the landscape, as well as local stream morphology, are likely to affect riparian and stream communities, including occupancy of semi-aquatic mammals. To gain a better understanding of how changing landscapes may affect the occupancy of semi-aquatic mammals, we sought to identify aspects of the riparian system and stream structure at multiple scales that relate to the presence of beaver (Castor canadensis) and muskrat (Ondatra zibethicus), including their interactions with mink (Neovison vison) and river otter (Lontra canadensis). We estimated multi-season occupancy using 103 sites sampled over six seasons (2012-2014) in southern Illinois, USA. We hypothesized beaver and muskrat occupancy was related to multiple aspects of landscape and local habitat including land-cover, water availability, human disturbance, stream characteristics, and the presence of other semi-aquatic mammals. Beaver occupancy varied over time and was predicted by stream size, stream density, and land-cover at the landscape scale. Muskrat occupancy also varied over time and was related to local aspects of habitat including percentage of forest in the riparian area, channel incision, land-cover, and aspects of sediment chemistry. Our results indicate the importance of spatial and temporal variation, scale, and food and water availability for these semi-aquatic species. Beaver and muskrat are most likely to be affected by changes to water regimes including availability of permanent water sources due to changing landscapes.

Streams and adjacent riparian habitats represent linked terrestrial and aquatic ecosystems that exchange materials and energy. Recognized relationships among apex predators and ecosystem biodiversity led us to hypothesize that these predators in riparian‐stream systems were more likely to be found in sites with high stream quality, defined as increased ecosystem function and integrity. In our freshwater study system, river otter Lontra canadensis and mink Neovison vison play critical roles as apex predators. We used multi‐season occupancy modelling across three sampling years (2012–2014) to compare aspects of the stream communities that explain occupancy dynamics of river otter and mink, including their interactions with other semi‐aquatic mammals. We surveyed for semi‐aquatic mammals at 77 sites in 12 major watersheds in southern Illinois, USA (44 526 km 2 ). Naïve occupancy differed among years but generally increased for river otter, and remained high (≥93.5%) for mink. Increasing substrate availability increased detectability of river otter, whereas mink detection varied by survey period. Occupancy of river otter during the initial survey period was higher in sites closer to reintroduction points. Probability of colonization of river otter was positively associated with macroinvertebrate index of biotic integrity, fish species richness, and beaver presence. Sites with high species richness of fish families preferred by river otter also had increased river otter persistence. Mink occupied sites with increased fish richness, muskrat presence and mussel community index. Taken together, our results show occupancy of both mink and river otter were predicted by aspects of prey diversity and presence, indicating the importance of community composition in occupancy dynamics of riparian predators. Ultimately, these relationships suggest that habitat heterogeneity and system stability are important to apex predator site use. However, the relative role of bottom–up and top–down forcing in stream systems remains to be resolved.

Habitat loss, land-use transformation, climate change, and biological invasions all elevate the importance of plasticity in food selection for the continued persistence of dietary specialists. Horned lizards (Phrynosoma spp.) are myrmecophagic specialists and the abundance of ant prey make their populations vulnerable to habitat loss, as well as invasive ants and associated pest control programs. We studied ant use by Phrynosoma cornutum (Texas Horned Lizards) on an insular urban reserve in central Oklahoma that was bereft of harvester ants (Pogonomyrmex spp.), presumed to be their chief prey. The five most commonly available ant genera based on bait station captures were Monomorium (69%), Forelius (11%), Pheidole (10%), Crematogaster (7%), and Tapinoma (2%). Based on the examination of 124 scat samples from adult and juvenile P. cornutum, Crematogaster (81%), Pheidole (12%), Formica (6%), and Monomorium (1%) were used as prey. Consumption of prey in several ant genera by P. cornutum disproportionately to their availability was related to ant mass and presumed nutritional value. Among juveniles, gape size did not influence Pheidole use but may influence Formica use. We suggest that P. cornutum are adaptive ant specialists whose populations might be maintained in habitat fragments without harvester ants as long as abundant medium-and large-sized native ant communities are present. Therefore, urban reserves, when effectively managed for native fauna, can conserve declining native species by serving as habitat havens in an otherwise unsuitable landscape.

Abstract Food webs composed of similar consumers can vary based on nutrient input, habitat structure, and other factors. For wetland‐associated species, fluctuating water levels can potentially affect habitat quality, which in turn can affect trophic diversity. Our objective was to determine spatiotemporal variation in the trophic structure of small mammals at two wetland complexes (floodplain and mineland) in southern Illinois. We live‐trapped small mammals during 2011–2013 at nine wetland patches on the Mississippi River floodplain and 14 patches at a reclaimed mineland. We collected hair samples from six species of small mammals (n = 428) at these wetland complexes. We analyzed C and N stable isotopes for three mammal taxa (Oryzomys palustris, Peromyscus spp., Microtus ochrogaster) to compare diet between species, sites, and times. Food sources (vegetation and invertebrates) were collected to form the isotopic baseline. We found no seasonal difference in diet composition, but isotopic values varied between sites and species. At the floodplain site, both δ15N and δ13C isotopic values for Oryzomys were more variable and completely enclosed that of Peromyscus. At the mining site, Peromyscus were at a lower trophic level (δ15N) and had a separate and less variable δ13C values from Oryzomys. Microtus was at a lower trophic position than the other two species at both sites. These results point to reduced niche overlap between Oryzomys and Peromyscus at the mining site, perhaps due to lower habitat quality and limited suitable resources. At the floodplain site, we conclude that more dynamic hydrology gave rise to higher biodiversity and more resources allowing small mammals to use similar food items.

Key factors affecting metapopulation dynamics of animals include patch size, isolation, and patch quality. For wetland-associated species, hydrology can affect patch availability, connectivity, and potentially habitat quality; and therefore drive metapopulation dynamics. Wetlands occurring on natural river floodplains typically have more dynamic hydrology than anthropogenic wetlands. Our overall objective was to assess the multiyear spatial and temporal variation in occupancy and turnover rates of a semi-aquatic small mammal at two hydrologically distinct wetland complexes. We live-trapped marsh rice rats (Oryzomys palustris) for 3yr and >50000 trap nights at nine wetland patches on the Mississippi River floodplain and 14 patches at a reclaimed surface mine in southern Illinois. We used dynamic occupancy modeling to estimate initial occupancy, detection, colonization, and extinction rates at each complex. Catch per unit effort (rice rats captured/1000 trap nights) was markedly higher at the floodplain site (28.1) than the mining site (8.1). We found no evidence that temperature, rainfall, or trapping effort affected detection probability. Probability of initial occupancy was similar between sites and positively related to patch size. Patch colonization probability at both sites was related negatively to total rainfall 3weeks prior to trapping, and varied across years differently at each site. We found interacting effects of site and rainfall on extinction probability: extinction increased with total rainfall 3months prior to trapping but markedly more at the floodplain site than at the mining site. These site-specific patterns of colonization and extinction are consistent with the rice rat metapopulation in the floodplain exhibiting a habitat-tracking dynamic (occupancy dynamics driven by fluctuating quality), whereas the mineland complex behaved more as a classic metapopulation (stochastic colonization & extinction). Our study supports previous work demonstrating metapopulation dynamics in wetland systems being driven by changes in patch quality (via hydrology) rather than solely area and isolation.

Abstract Large carnivores are recolonizing parts of North America and Europe as a result of modern management and conservation policy. In the midwestern USA, black bears Ursus americanus, cougars Puma concolor and grey wolves Canis lupus have the potential to recolonize provided there is suitable habitat. Understanding where large carnivores may become re-established will prepare resource professionals for the inevitable ecosystem effects and potential human–carnivore conflicts associated with these species. We developed individual and combined models of suitable habitat for black bears, cougars and wolves in 18 midwestern states, using geospatial data, expert-opinion surveys, and multi-criteria evaluation. Large, contiguous areas of suitable habitat comprised 35, 21 and 13% of the study region for wolves, bears and cougars, respectively. Approximately 12% of the region was considered suitable for all three species. Arkansas, Minnesota, Texas and Wisconsin had the highest proportions (> 40%) of suitable habitat for black bears; Arkansas, Michigan, Missouri, Texas and Wisconsin had the highest proportions (≥ 20%) of suitable habitat for cougars; and only in four states in the study region was < 29% of land suitable wolf habitat. Models performed well when validated by comparing suitability values of independent sets of known carnivore locations to those of random locations. Contiguous areas of suitable habitat typically spanned multiple states, thus coordination across boundaries and among agencies will be vital to successful conservation of these species. Our models highlight differences in habitat requirements and geographical distribution of potential habitat among these carnivores, as well as areas vital to their persistence in the Midwest.

Matrix land cover types differ in permeability to animals moving between habitat patches, and animals may actually move faster across less-suitable areas. Marsh rice rats are wetland specialists whose dispersal crosses upland matrix.

The marsh rice rat (Oryzomys palustris) inhabits wetlands that are often fragmented and isolated by upland cover types. Persistence of marsh rice rat populations and metapopulations likely depends on their ability to enter and traverse the upland matrix, yet basic information, such as home-range size and landcover use patterns, is lacking. Our goal was to quantify home-range size and habitat selection by marsh rice rats in southern Illinois. Between March and November 2011, we radiocollared 21 male rice rats (8 subadults and 13 adults) that were each located 7 to 24 times each via triangulation and homing. We estimated home-range size, compared landcover composition within kernel home ranges to what was available in the surrounding landscape, and quantified daily movement distances. Mean (+/- SE) home ranges were 3.53 +/- 0.66 ha based on 95% kernel isopleths and 1.85 +/- 0.49 ha based on minimum convex polygons. Home ranges were largest for individuals followed in early summer, but home-range sizes were similar for adults and subadults. Rice rats' use of emergent wetland vegetation was greater than availability, indicating they preferred emergent wetlands habitat at the home-range level. However, upland cover types made up > 40% of each home range, on average. Daily movements averaged 46.6 +/- 3.4 m (maximum: 396 m), and rice rats were located up to 464 m from the nearest wetland. Based on by far the largest sample size (in individuals and locations per individual) available for space use of the marsh rice rat, our findings support the characterization of male rice rats as highly vagile and suggest that rice rats move through upland cover more frequently than previously described.

bears averaged 14.5 and 21.0 km 2 as estimated by minimum convex polygon and adap- tive kernel methods, respectively. Based on compositional analysis, pine-hardwood and oak-hardwood poletimber stands were the highest-ranked habitat types at the study-area scale annually and during summer, whereas sawtimber of shortleaf pine (Pinus echinata), regeneration areas, and oak-hardwood sawtimber were the highest-ranked habitats at the home-range scale. Selection varied on a seasonal basis and by scale, but bears consistently avoided pine-hardwood sawtimber stands. The unusual preference for pine stands by black bears in our area may be tied to local forest management practices, which include thinning and burning. © 2007 Oklahoma Academy of Science

Carnivore guilds play a vital role in ecological communities by cascading trophic effects, energy and nutrient transfer, and stabilizing or destabilizing food webs. Consequently, the structure of carnivore guilds can be critical to ecosystem patterns. Body size is a crucial influence on intraguild interactions, because it affects access to prey resources, effectiveness in scramble competition, and vulnerability to intraguild predation. Coyotes (Canis latrans), bobcats (Lynx rufus), gray foxes (Urocyon cinereoargenteus), raccoons (Procyon lotor), red foxes (Vulpes vulpes), and striped skunks (Mephitis mephitis) occur sympatrically throughout much of North America and overlap in resource use, indicating potential for interspecific interactions. Although much is known about the autecology of the individual species separately, little is known about factors that facilitate coexistence and how interactions within this guild influence distribution, habitat use, and temporal activity of the smaller carnivores. To assess how habitat autecology and interspecific interactions affect the structure of this widespread carnivore guild, we conducted a large-scale, non-invasive carnivore survey using an occupancy modeling framework. We deployed remote cameras during 3-week surveys to detect carnivores at 1,118 camera locations in 357 2.6-km(2) sections (3-4 cameras/section composing a cluster) in the 16 southernmost counties of Illinois (16,058 km(2)) during January-April, 2008-2010. We characterized microhabitat at each camera location and landscape-level habitat features for each camera cluster. In a multistage approach, we used information-theoretic methods to evaluate competing models for detection, species-specific habitat occupancy, multispecies co-occupancy, and multiseason (colonization and extinction) occupancy dynamics. We developed occupancy models for each species to represent hypothesized effects of anthropogenic features, prey availability, landscape complexity, and vegetative land cover. We quantified temporal activity patterns of each carnivore species based on their frequency of appearance in photographs. Further, we assessed whether smaller carnivores shifted their diel activity patterns in response to the presence of potential competitors. Of the 102,711 photographs of endothermic animals, we recorded photographs of bobcats (n=412 photographs), coyotes (n=1,397), gray foxes (n=546), raccoons (n=40,029), red foxes (n=149), and striped skunks (n=2,467). Bobcats were active primarily during crepuscular periods, and their activity was reduced with precipitation and higher temperatures. The probability of detecting bobcats decreased after a bobcat photograph was recorded, suggesting avoidance of remote cameras after the first encounter. Across southern Illinois, bobcat occupancy at the camera-location and camera-cluster scale (local=0.240.04, camera cluster cluster=0.750.06) was negatively influenced by anthropogenic features and infrastructure. Bobcats had high rates of colonization (=0.86) and low rates of extinction (E=0.07), suggesting an expanding population, but agricultural land was less likely to be colonized. Nearly all camera clusters were occupied by coyotes (cluster=0.95 +/- 0.03). At the local scale, coyote occupancy (local=0.58 +/- 0.03) was higher in hardwood forest stands with open understories than in other areas. Compared to coyotes, gray foxes occupied a smaller portion of the study area (local=0.13 +/- 0.01, cluster=0.29 +/- 0.03) at all scales. At the scale of the camera cluster, gray fox occupancy was highest in fragmented areas with high proportions of forest, and positively related to anthropogenic features within 100% home-range buffers. Red foxes occupied a similar proportion of the study area as gray foxes (local=0.12 +/- 0.02, cluster=0.26 +/- 0.04) but were more closely associated with anthropogenic features. Only anthropogenic feature models made up the 90% confidence set at all scales of analysis for red foxes. Extinction probabilities at the scale of the camera cluster were higher for both gray foxes (E=0.57) and red foxes (E=0.35) than their colonization rates (gray fox =0.16, red fox =0.06), suggesting both species may be declining in southern Illinois. Striped skunks occupied a large portion of the study area (local=0.47 +/- 0.01, cluster=0.79 +/- 0.03) and were associated primarily with anthropogenic features. Raccoons were essentially ubiquitous within the study area, being photographed in 99% of camera clusters. We observed little evidence for spatial partitioning based on interspecific interactions, with the exception of the gray fox-coyote pairs, and found that habitat preferences were more important in structuring the carnivore community. Habitat had a stronger influence on the occupancy of foxes than did the presence of bobcats. However, the level of red fox activity was negatively correlated with bobcat activity. Gray fox occupancy and the number of detections within occupied sites were reduced in camera clusters occupied by coyotes but not bobcat occupancy. Overall, gray fox occupancy was highest at camera locations with fewer hardwood and more conifer trees. However, gray foxes were more likely to occupy camera locations in hardwood stands than conifer stands if coyotes were also present indicating that hardwood stands may enhance gray fox-coyote coexistence. The 2 fox species appeared to co-occur with each other at the local scale more frequently than expected based on their individual selection of habitat. Similarly, occupancy of camera location by red foxes was higher when coyotes were present. These positive spatial associations among canids may be a response to locally high prey abundance or unmeasured habitat variables. Activity levels of raccoons, bobcats, and coyotes were all positively correlated. Overall, our co- occurrence and activity models indicate competitor-driven adjustments in space use among members of a carnivore community might be the exception rather than the norm. Nevertheless, although our results indicate that gray foxes and red foxes currently coexist with bobcats and coyotes, their distribution appears to be contracting on our study area. Coexistence of foxes with larger carnivores may be enhanced by temporal partitioning of activity and by habitat features that reduce vulnerability of intraguild predation. For instance, hardwood stands may contain trees with structure that enhances tree-climbing by gray foxes, a behavior that probably facilitates coexistence with coyotes. Efforts to enhance gray fox populations would likely benefit from increasing the amount of mature oak-hickory forest. Additionally, the varying results from different scales of analyses underscore the importance of considering multiple spatial scales in carnivore community studies. (c) 2015 The Wildlife Society.

ABSTRACT Large carnivores are recolonizing portions of midwestern North America given harvest protection and the presence of suitable habitat in the region. Perhaps more so than other species, the successful management and viability of large carnivore populations is as dependent on social acceptance as on biological factors. However, knowledge of human attitudes and perceptions toward large carnivores in much of the Midwest remains unknown. We assessed attitudes and perceptions of Illinois citizens about black bears ( Ursus americanus ), cougars ( Puma concolor ), and gray wolves ( Canis lupus ) via a mail survey to provide wildlife managers with an understanding of residents' views prior to formulating carnivore management plans. The survey instrument consisted of questions about large carnivores regarding knowledge and beliefs, experiences and encounters, attitudes toward carnivores and management, and demographic questions and behavioral characteristics. We surveyed residents statewide; the sample drawn was stratified by geographic region (northern, central, and southern) and urban or rural county designation within regions. Because we observed differences in demographic variables between respondents (by mail) and non‐respondents (telephone interviewees), we did not pool responses from the 2 groups for analysis; the final response rate for the survey was 13%. More than 70% of survey respondents ( n = 791) were male and their average age was 60; 55% were hunters. Approximately 40% were unsure about the population status of large carnivores in Illinois; of the remaining respondents, most (ranging from 20% for black bears to 41% for cougars) believed the presence of all 3 focal species had increased over the past decade. More residents supported protection (43%) and increasing numbers of large carnivores (39%) than opposed them (26%); however, support for black bears was slightly higher than for cougars and wolves. Rural residents and livestock owners were the most likely to want carnivore numbers to decrease and least likely to support their protection; higher levels of education corresponded to positive attitudes toward large carnivores. Our research provides the foundation for well‐informed management plans, policy decisions, and educational initiatives for large carnivores in midwestern states where these species appear to be recolonizing following decades of absence. © 2014 The Wildlife Society.

Woody plant encroachment in natural grasslands is a widely documented global phenomenon that alters ecosystem dynamics by altering historic vegetation composition and suppressing herbaceous productivity. Abundant woody plants often suppress native plants sufficiently to establish successional thresholds difficult to reverse without species augmentation. Juniper (Juniperus virginiana L.) is expanding in North American tallgrass prairie, but it is currently unknown if encroachment creates successional restrictions that limit restoration potential. We selected 16 50×50-m sites with juniper canopy cover ranging from zero to approximately 75% in tallgrass prairie near Stillwater, Oklahoma, USA. Juniper trees were removed from 7 of the sites along the gradient of juniper canopy cover. Canopy cover of plant species and herbaceous plant productivity were estimated at each site 1 year before and 1, 2, and 5 years after tree removal. Before trees were removed, plant species richness and productivity declined as juniper canopy cover increased, and plant community composition dissimilarity of reference sites increased as juniper canopy cover increased. These relationships remained consistent on all non-removal sites throughout the study. The first year after juniper removal, species richness increased on all removal sites compared to intact sites and productivity on removal sites increased two years after removal. Plant community dissimilarity between reference sites and juniper removal sites remained relatively high (30–60%) the first two years after tree removal on all removal sites, but dissimilarity was about 22% 5 years after juniper removal. Within 5 years, removal sites were comparable to reference plant communities. Grassland restoration frequently requires species manipulation and additional seeding, particularly when overcoming successional limitations. Juniper encroachment into tallgrass prairie alters plant community species composition and productivity. However, in our study, juniper associated succession limitations were not apparent, and complete autogenic restoration was achieved within 5 years without seeding or species manipulation.

Demographic studies of imperiled populations can aid managers in planning conservation actions. However, applicability of findings for a single population across a species’ range is sometimes questionable. We conducted long-term studies (8 and 9 years, respectively) of 2 populations of the lizard Phrynosoma cornutum separated by 1000 km within the historical distribution of the species. The sites were a 15-ha urban wildlife reserve on Tinker Air Force Base (TAFB) in central Oklahoma and a 6000-ha wildland site in southern Texas, the Chaparral Wildlife Management Area (CWMA). We predicted a trade-off between the effect of adult survival and fecundity on population growth rate (λ), leading to population-specific contributions of individual vital rates to λ and individualized strategies for conservation and management of this taxon. The CWMA population had lower adult survival and higher fecundity than TAFB. As predicted, there was a trade-off in the effects of adult survival and fecundity on λ between the two sites; fecundity affected λ more at CWMA than at TAFB. However, adult survival had the smallest effect on λ in both populations. We found that recruitment in P. cornutum most affected λ at both sites, with hatchling survival having the strongest influence on λ. Management strategies focusing on hatchling survival would strongly benefit both populations. As a consequence, within the constraint of the need to more accurately estimate hatchling survival, managers across the range of species such as P. cornutum could adopt similar management priorities with respect to stage classes, despite intra-population differences in population vital rates.

Oak-dominated forest has declined in the eastern United States as shade-tolerant mesophytic species (e.g., maple [Acer spp.]) replace oaks (Quercus spp.), sparking concern among ecologists regarding species that consume acorns. Our goal was to describe how increasing mesophication of oak forests may affect consumers in higher trophic levels. We investigated relationships among forest composition, mast production, small-mammal density, and carnivore occurrence in 8 stands representing a gradient of oak hickory dominance in central hardwood forest in southern Illinois. We livetrapped small mammals for >24,000 trap-nights in June-August 2009-2011 with trapping webs to estimate population density of mice (Peromyscus spp.). We collected mast seeds during October-November 2009-2010 and calculated average dry biomass (g/m(2)) for each species and stand. During winters 2009-2011, we photographed carnivores using baited camera traps. We regressed mast biomass on measures of forest composition and regressed Peromyscus density and carnivore occurrence on estimates of mast biomass. Peromyscus summer density was not related to percent hard-mast basal area or hard-mast biomass from the previous autumn. Logistic regressions of carnivore occurrence on Peromyscus density were not significant. Many other studies have demonstrated links of several species to oak forest and mast production, but the lack of associations that we observed was consistent with recent meta-analyses across latitude. The landscape matrix of oak hickory forest and alternative soft-mast foods also may act to homogenize Peromyscus density across our study sites. Maintenance of stand heterogeneity in the forest landscape will support a wider diversity of species.

Abstract:  Disturbance caused by habitat restoration or urbanization can threaten populations of sensitive wildlife species. We examined the effects of habitat disturbance on the ecology of an urban population of Texas Horned Lizards (Phrynosoma cornutum), a species of conservation concern in several states as a result of range-wide declines. We quantified changes in spatial distribution, survival rates, and population size and density over 9 yr (2003–2011) for a P. cornutum population on an urban reserve. The project was divided into three, 3-yr stages based on level of habitat disturbance. Spatial analyses did not support the hypothesis that disturbance associated with restoration activities affected the spatial ecology of P. cornutum on our study site. However, these results were not entirely conclusive due to the logistical constraints of working on a single site with an uncommon species. Survival (n = 147 lizards) was affected by season (inactive-season survival was higher), stage (declining survival in later stages with more disturbance), an interaction of season and stage, and disturbance (covariate of proportion of an individual's home range in disturbed areas for a given year; small negative effect). Major causes of mortality included depredation and anthropogenic activity. We estimated a population size of 33 ± 5 (95% CI of 28–49) individuals (excluding hatchlings) with a corresponding density of 2.68 lizards/ha in 2011, which represented a 38% decline since 2005. This decline was likely a consequence of two factors: the 2008 translocation of 17 adult lizards from an area adjacent to our study site impacted by housing development and a decrease in the annual survival rate of adults over time. Our case study addressed recent calls to examine specific mechanisms by which habitat loss and degradation affect herpetofauna and revealed classic responses of an isolated population to stochastic events and anthropogenic activities.

Correlative and process-based approaches to describing the ecological niche in a spatially explicit fashion have often been compared in an adversarial framework. We sought to compare niche models developed via classic (correlative only), niche (process-based information), and hybridized (correlative augmented with process-based derived information) approaches, with the goal of determining if the added effort of process-based model development yielded better model fit. Correlative data layers (i.e., habitat models) included vegetation community types. Euclidean distance statistics, neighborhood analyses, and topographically-derived information. Mechanistic data layers were estimates of thermal suitability derived from field-collected datasets and biophysical calculations, and estimates of prey biomass interpolated from monitoring stations. We applied these models at high resolution (1 m x 1 m pixel size) to habitat occupied by a population of Texas horned lizards (Phrynosoma cornutum) located in central Oklahoma. Results suggested that our treatment of process-based information offered dramatically better identification of suitable habitat when compared to correlative information, but that these results were likely due to low variability of niche variable pixel values. Niche layers nearly perfectly predicted lizard locations; the interpretation of these results suggest that lizards occupy habitat based on thermal suitability over the duration of a field season. Given the low variability observed in thermal suitability layers, we question the ecological reality of these predictions. Correlative models may accurately describe the niche at small spatial scales, and may suffice in situations where time and financial resources are limiting constraints on project goals. Process-based information continues to be an important part of the niche, and may offer additional predictive accuracy via correlative approaches when included in an ecologically meaningful context. (C) 2012 Elsevier B.V. All rights reserved.

Genetic analyses can facilitate large-scale conservation planning for wide-ranging species capable of long-distance dispersal. Bobcats (Lynx rufus) are the most broadly distributed native felid in North America, and are managed on a “state-by-state” basis. Little is known about the distribution of genetic diversity across bobcats’ range. We examined genetic differentiation among bobcats from throughout their distributional range in North America using 10 microsatellite loci and mitochondrial control region sequence to elucidate patterns of genetic diversity. Both markers revealed significant regional genetic differentiation. Additionally, genetic diversity estimates, population expansion statistics, and the haplotype network elucidated from mitochondrial DNA analyses, suggest that populations in the West and East/Midwest experienced historical population expansions, with the East/Midwest likely undergoing periodic range contractions and extirpations during bobcat colonization. Microsatellite data revealed significant regional genetic differentiation between the Midwest and East, as well as the West, suggesting that recent barriers to gene flow may be affecting dispersal of bobcats. These analyses indicate that conservation of forested areas will be crucial for maintaining gene flow throughout bobcats’ range as human populations increase and that multi-state consortia may be a more appropriate way to manage bobcats as this scenario will conserve both historical and current levels of genetic diversity.