We compared relative impacts of habitat type vs. location in the diet of a generalist omnivore, the raccoon (Procyon lotor). Raccoon diets were analyzed from 161 scat samples collected in a marine coastal habitat over 13 mo. We used a suite of statistical tools including univariate indices of diversity, descriptive statistics, niche similarity analyses, and two contrasted randomization algorithms with Monte Carlo to test whether raccoons maintained similar diets in different habitats. We compared these results to raccoon diet studies in geographically distant locations with similar habitats to relevant studies conducted geographically closer but with different habitats. Logistic regression analyses revealed that among habitat similarity, geographic closeness, and diet diversity (i.e., relative dietary specialization of each population), only habitat similarity significantly (and positively) influenced probability of observing a greater-than-expected diet similarity. This demonstrated that raccoons in similar habitats had similar diets, with substitution of ecologically equivalent prey species.

Home range size, daily travel distances, and diel activity patterns are important characteristics of how an animal uses its home range area. In species, such as the bobcat (Lynx rufus), with large geographical ranges, it is necessary to gather data on diverse populations across the range to better understand what might be factors influencing these home range parameters. Although there are many studies of bobcats in more northern areas of its range in the United States, few data exist from its extensive southern range in Mexico. To fill this gap in information, we collected data on home range size, daily travel distances, and diel activity patterns of bobcats from the center of the Chihuahuan Desert in Mexico. We compared our findings with available data from more northern studies and tested for any latitudinal trends in home range size. We trapped eight adult bobcats (four females and four males) between 2006 and 2008 at the Mapimi Biosphere Reserve in the Chihuahuan Desert. Each bobcat was equipped with a GPS radio collar that estimated their location and ambient temperature every half hour at night (1900 to 800 h), and every hour during the day (800 to 1900 h). These data were used to estimate total daily distance traveled, average speed, home range size, activity pattern, and to test for an association between hourly travel and ambient temperature. For bobcats in Mapimi, mean distances traveled daily (4.9 ± 0.7 km), mean speed (0.3 ± 0.4 km/h) and average home range size (25.9 km² ± 3.7) did not differ from other places in U.S. (distance traveled daily 5.7 ± 1.4 km, mean speed 0.4 ± 0.4 km/h and home range size 34.0 ± 5.4 km²). Bobcats are most active from 1700 to 2300 h and from 0500 to 1200 h and showed a minimum activity period from 1300 to 1600 h. These patterns did not differ from what other studies found. Distance traveled was inversely correlated with environmental temperature (r²  =  0.506, P < 0.05). Our data demonstrate that most behaviors of bobcats in this hot desert environment did not differ in general from their more northern populations. Although our home range estimates were similar to other studies, our analysis did support a latitudinal decreasing trend that indicates factors other than those related to latitude are affecting home range size in bobcats. We suggest investigating other independent factors not related with latitude such as primary production and rainfall might help identify which, if any, of these factors contribute to home range size in bobcats.

Although habitat fragmentation is recognized as a primary threat to biodiversity, the effects of urban development on genetic population structure vary among species and landscapes and are not yet well understood. Here we use non-invasive genetic sampling to compare the effects of fragmentation by major roads and urban development on levels of dispersal, genetic diversity, and relatedness between paired bobcat populations in replicate landscapes in coastal southern California. We hypothesized that bobcat populations in sites surrounded by urbanization would experience reduced functional connectivity relative to less isolated nearby populations. Our results show that bobcat genetic population structure is affected by roads and development but not always as predicted by the degree that these landscape features surround fragments. Instead, we suggest that urban development may affect functional connectivity between bobcat populations more by limiting the number and genetic diversity of source populations of migrants than by creating impermeable barriers to dispersal.

Movement ecology of coyotes (Canis latrans) in the southeastern United States is poorly understood, despite the increasing recognition that coyotes are important predators throughout the region. During 2009–2011, we documented long-distance movements of three transient coyotes in northeastern North Carolina using Global Positioning System (GPS) collars. From their capture locations, distances traveled by the coyotes were 393 km, 280 km, and 77 km. Mean daily distance traveled during transient movements was 6.7 km/day, 5.2 km/day, and 2.8 km/day, respectively. Maximum distances traveled in a day were 21.0 km, 18.8 km, and 9.5 km, respectively. After moving 393 km west, one coyote settled southeast of Durham, NC and established a home range of 35.0 km² within a primarily suburban landscape. During transiency, all three coyotes maintained biding areas ranging from 6.6 km² to 43.7 km² for 11–52 d. Our findings illustrate the complexities of coyote movement and demonstrate that coyotes can traverse long distances and quickly establish home ranges in rural and suburban landscapes of the southeastern United States.

The adult sex ratio (ASR) is an important component of a population's demographics and can be used as an indicator of a population's status. However, the causes of annual variation in ASRs are unknown for many species. Fluctuations in ASR can arise through demographic stochasticity and intense selective harvesting. In this study we investigate the long-term patterns of variation in the ASRs (bucks: 100 does) for four populations of pronghorn (Antilocapra americana) in western Nebraska. We used multiple variables in a model selection process to predict annual fluctuation of pronghorn ASRs. We found that the number of bucks: 100 does significantly varied over the four populations. The best predictors of annual variation in pronghorn ASRs were variable across all populations. The number of pronghorn bucks harvested in the previous year's hunting season and the previous year's density of pronghorn were the most common predictors of ASR fluctuation. Buck harvest was an important predictor variable in only two of the four populations. Variation of harvest strategies within the populations could account for the lack of importance of buck harvest in half of the populations. The relationship between density and ASR is novel but difficult to interpret due to lack of data on birth sex ratios and fawn survival. More data on pronghorn demographics are needed in order to better explain the connection between density and ASR.

Examination of age structures and sex ratios is useful in the management of northern river otters (Lontra canadensis) and other furbearers. Reintroductions and subsequent recolonizations of river otters have been well documented, but changes in demographics between expanding and established populations have not been observed. As a result of reintroduction efforts, immigration from Arkansas and northeastern Texas, and other efforts, river otters have become partially reestablished throughout eastern and central Oklahoma. Our objective was to examine age structures of river otters in Oklahoma and identify trends that relate to space (watersheds, county) and time (USDA Animal and Plant Health Inspection Service county trapping records). We predicted that river otters in western areas of the state were younger than river otters occurring farther east. From 2005–2007, we obtained salvaged river otter carcasses from federal and state agencies, and we live-captured other river otters using leg hold traps. Seventy-two river otters were sampled. Overall, sex ratios were skewed toward females (1F∶0.8M), but they did not differ among spatiotemporal scales examined. Teeth were removed from salvaged and live-captured river otters (n  =  63) for aging. One-year old river otters represented the largest age class (30.2%). Proportion of juveniles (<1 y old) in Oklahoma (19.0%) was less than other states. Mean age of river otters decreased from east-to-west in the Arkansas River and its tributaries. Mean age of river otters differed between the Canadian River Watershed (0.8 y) and the Arkansas River Watershed (2.9 y) and the Canadian River Watershed and the Red River Watershed (2.4 y). Proportion of juveniles did not differ among spatiotemporal scales examined. Similar to age structure variations in other mammalian carnivores, colonizing or growing western populations of river otters in Oklahoma contained younger ages than more established eastern populations.

Human development is changing the landscape in many ways that affect the distribution of wild species of mammals. Most previous work has focused on birds with only a few studies that examine the effects of urbanization on mammalian species. Using a combination of live trapping, track plates, and observation, we collected preliminary data in which we quantified patterns of species distributions across a rural-urban gradient in southwestern Ohio. Individual species responded differently to aspects of human development. As seen in some previous avian but not mammalian studies, mammalian species richness was greatest at intermediate levels of development. Using cluster analysis, we were able to group sites into three types based on species richness: the most rural sites, those with a moderate degree of development, and the most urban site. This study shows that mammals respond to urbanization in similar ways to birds and butterflies and suggests that different variables may be necessary to explain the observed patterns.

Understanding human impacts on biodiversity is a pressing challenge given the degree to which humans alter ecosystems. Urbanization is a prevalent example of human disturbance that often reduces species richness at the expense of dramatic population growth for certain urban-adapted taxa. The Western black widow spider, Latrodectus hesperus, is a medically-important pest species that thrives around human disturbance including urbanized habitats of the desert Southwest (e.g., Phoenix, AZ). Population growth in this urban pest may be explained by supplemental water usage, heightened productivity, and prey abundance in urbanized deserts. Here we compare several life history parameters between spiders from representative urban and desert sites. Our urban site proved more densely populated than our desert site; however, urban spiders were in significantly worse body condition, made fewer eggs, and invested less in individual eggs compared to desert spiders. Thus, the natural history of this urban pest appears too complex to be explained simply by urban resource abundance. We suggest several alternatives to explain this counterintuitive finding.

Alterations of aquatic ecosystems, such as nutrient enrichment and changes in community composition, can potentially have effects that pervade the entire community. We investigated the effects of nutrient enrichment and changes in the presence and density of two species of tadpoles, American toad (Anaxyrus americanus) and Gray treefrog (Hyla versicolor), on freshwater snail abundance (Physella sp.). At low tadpole density, there was no difference in the abundance of Physella sp. among treatments. At high tadpole density, treatments with both species of tadpoles present and nutrient enrichment had a higher abundance of Physella than all other treatment combinations. Mesocosms with high tadpole densities had lower periphyton dry mass than those with low overall tadpole density. At the end of the experiment, increased abundance of Physella was related to earlier metamorphosis in A. americanus and H. versicolor and higher proportions of H. versicolor metamorphosing and surviving. Nutrient enrichment did not independently affect snails. Our results suggest that changes in the composition and density of tadpole assemblages can interact with nutrient enrichment to drive variation in freshwater snail abundances, indicating that ongoing declines in amphibian populations combined with continued anthropogenic nutrient enrichment of freshwater ecosystems may have complex effects on freshwater snail populations.

The exotic invasive wetland plant purple loosestrife (Lythrum salicaria) is often considered to have negative impacts on native plant and animal species, but this is debated. Clarifying its influence would provide insight into appropriate management actions following invasion. We investigated the influence of L. salicaria cover and density on abundances of wetland bird species that are associated with a variety of vegetation structures. We found evidence of relationships between L. salicaria measures and abundance for most species we examined, but these relationships did not always agree with our predictions based on species' habitat associations. Some bird species positively responded whereas others negatively responded to increasing L. salicaria cover or density. Response curves varied in complexity and included linear and quadratic relationships as well as interactions. Our results suggested that L. salicaria did not categorically decrease habitat quality for all wetland bird species, and it may have had a positive influence on quality for some species. This ambiguity is not unique to L. salicaria invasion but applies to many changing habitat features. Therefore, there is likely no single appropriate strategy for managing L. salicaria when the goal is to maintain a diverse avian community in which species have divergent habitat preferences.

Garlic mustard, Alliaria petiolata (M. Bieb.) Cavara & Grande, is an introduced biennial forb that has commonly been referred to as highly invasive and as having substantial negative effects on other plants in the eastern deciduous forests of North America. However, several recent studies have documented only modest effects on other plant species, raising questions as to the extent of the threat really posed by A. petiolata. Alliaria petiolata often exhibits an alternating two-year life-history cycle, with high rosette years alternating with high flowering stem years. It has been proposed that this cycle is partly driven by intraspecific competition between the stems and the rosettes. In a two-year study, we extensively sampled A. petiolata in a Minnesota woodland at two spatial scales, including 6.5 km of belt transects in a 6.8 ha study grid (20 × 20 m cells) and 90 small sampling quadrats (1.0 × 0.5 m) within the grid. At the large scale, we compared seed bank abundance and diversity of other herbaceous plants with A. petiolata abundance. Using the monitoring data we also investigated whether this population was exhibiting an alternating two-year life-history cycle, consistent with the intraspecific competition hypothesis for this phenomenon. At the small scale, we compared A. petiolata abundance with the abundance of other plants, including herbs, ferns, shrubs, and tree seedlings. We also conducted an ex-situ pot experiment in which we planted seeds of six tree species in soil collected from dense A. petiolata patches and soil collected where A. petiolata was absent and recorded emergence rates and seedling growth over an 8 wk period. Overall, we found little evidence that A. petiolata was negatively affecting other plant species. This is consistent with other recent studies and indicates that, despite earlier claims to the contrary, A. petiolata seems to be more a product than an agent of change in eastern North American deciduous forests. We also documented an alternating two-year life-history cycle, providing additional evidence to support the hypothesis that this cycle is at least partly being driven by intraspecific competition.

Interactions between environmental variables in anthropogenically disturbed environments and physiological traits of invasive species may help explain reasons for invasive species' establishment in new areas. Here we analyze how soil contamination along roadsides may influence the establishment of Conium maculatum (poison hemlock) in Cook County, IL, USA. We combine analyses that: (1) characterize the soil and measure concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) where Conium is growing; (2) assess the genetic diversity and structure of individuals among nine known populations; and (3) test for tolerance to heavy metals and evidence for local soil growth advantage with greenhouse establishment experiments. We found elevated levels of metals and PAHs in the soil where Conium was growing. Specifically, arsenic (As), cadmium (Cd), and lead (Pb) were found at elevated levels relative to U.S. EPA ecological contamination thresholds. In a greenhouse study we found that Conium is more tolerant of soils containing heavy metals (As, Cd, Pb) than two native species. For the genetic analysis a total of 217 individuals (approximately 20–30 per population) were scored with 5 ISSR primers, yielding 114 variable loci. We found high levels of genetic diversity in all populations but little genetic structure or differentiation among populations. Although Conium shows a general tolerance to contamination, we found few significant associations between genetic diversity metrics and a suite of measured environmental and spatial parameters. Soil contamination is not driving the peculiar spatial distribution of Conium in Cook County, but these findings indicate that Conium is likely establishing in the Chicago region partially due to its ability to tolerate high levels of metal contamination.

In tallgrass prairie restoration, dominance by competitive late succession prairie grasses may cause loss of species that are poor competitors. In a field experiment we tested whether disturbance could reverse this process for Liatris scariosa var. nieuwlandii, a threatened savanna species thought to be a poor competitor. At our study site, this species appears to be stable in vegetation dominated by Danthonia spicata, an early successional grass, but declining in the presence of Andropogon gerardii, a dominant prairie grass restored to the study area. We used correlation analysis to test whether cover of grasses affected L. s. nieuwlandii abundance and experimental disturbance to test whether competition could be reduced. We disturbed soil at small (<100 cm²) and large (2.25 m²) scales within vegetation dominated by D. spicata or A. gerardii. We measured the response of L. s. nieuwlandii to disturbance by planting seeds within undisturbed and disturbed patches. In undisturbed patches, cover of D. spicata and A. gerardii was inversely related. Liatris s. nieuwlandii abundance was negatively correlated with A. gerardii cover (R²  =  0.58) but positively correlated with D. spicata cover (R²  =  0.98). In association with D. spicata, L. s. nieuwlanii abundance was significantly lower (<1/0.25 m²) within large scale disturbance plots than in small or no disturbance plots. In association with A. gerardii, L. s. nieuwlandii was absent from undisturbed plots but present (at <1/0.25 m²) in small and large scale disturbance plots. In vegetation dominated by D. spicata, native species richness was greater in undisturbed and small scale disturbance plots than in large scale disturbance plots. Non-native richness tended to be lower in large scale disturbance plots in both vegetation types compaired to small scale or no disturbance plots. The results support the hypotheses that disturbance of dominant grasses can reverse the competitive exclusion of L. s. nieuwlandii by late successional grasses and thus disturbance can mediate the coexistance of early and late successional species.

We investigated the changes in stand structure, species composition, and soil characteristics of jack pine (Pinus banksiana Lamb.) disjunct stands on the southern shore of Lake Michigan in North America. Our NMS (Non-metric Multidimensional Scaling) ordination revealed a chronosequence of the succession from jack pine stand to black oak (Quercus velutina Lam.) woodland. A majority of jack pine seedlings appeared to be recruited near wet pannes (shallow intradunal ponds with standing water) where the water table was relatively high, expanded in dry pannes, and followed by invasions of black oak and other upland tree species on dune ridges. Expansion of canopy cover, along with dominance of black oak, have likely led to a major reduction in herbaceous cover and a shift in the composition of the understory species. Species richness and diversity have increased. However, much of the increase was attributed to species that were not native to the Lake Michigan sand dunes. Soil pH and nitrogen concentration changed significantly from the younger wet panne to the older dune ridge plots, but other measures of soil fertility did not differ among the plots. The reduction in soil pH in the older plots was likely due to the neutralization of calcareous soil by carbonic acid leached from accreted sands and organic acids produced by litter decomposition. Nitrogen accumulation in the soil is expected to continue beyond the equilibrium values predicted from mature oak woodland soil. Jack pine seedlings have been documented to be tolerant of xeric conditions. However, we found that seedling survival was over five times higher in moist soil near the wet pannes. In this respect, failure in formation of new pannes may reduce the size of the region's jack pine population in the foreseeable future.

This study documents 25 y of change in the abundance of Quercus rubra (northern red oak) and Quercus alba (white oak), in a previous chestnut (Castanea castanea)-oak forest in the Southern Appalachians of the eastern U.S.A. Spatially explicit data from 1983–1984 and 2007–2008 of individually mapped trees on two plots in southwestern Virginia were used to examine how the basal area and density of all tree species changed, with specific attention to recruitment, growth, and mortality patterns of Q. rubra and Q. alba. Since the 1980s there has been an increase in the number of shade tolerant trees, primarily Acer pensylvanicum (striped maple), and a decrease in the number of shade intolerant and intermediate shade tolerant trees, including both Q. rubra and Q. alba. We found a negative correlation between A. pensylvanicum abundance and Quercus seedling abundance and a positive correlation between light availability and Quercus seedling abundance. Both Q. rubra and Q. alba have experienced self-thinning, and the previous oak-chestnut forest will likely become increasingly dominated by maples and other shade tolerant species.

Fine scale spatial mapping of historical tree records over large extents is important for determining historical species distributions. We compared performance of two ensemble methods based on classification trees, random forests, and boosted classification, for mapping continuous historical distributions of tree species. We used a combination of soil and terrain predictor variables to predict species distributions for 21 tree species, or species groups, from historical tree surveys in the Missouri Ozarks. Mean true positive rates and AUC values of all species combined for random forests and boosted classification, at a modeling prevalence and threshold of 0.5, were similar and ranged from 0.80 to 0.84. Although prediction probabilities were correlated (mean r  =  0.93), predicted probabilities from random forests generated maps with more variation within subsections, whereas boosted classification was better able to differentiate the restricted range of shortleaf pine. Both random forests and boosted classification performed well at predicting species distributions over large extents. Comparison of species distributions from two or more statistical methods permits selection of the most appropriate models. Because ensemble classification trees incorporate environmental predictors, they should improve current methods used for mapping historical trees species distributions and increase the understanding of historical distributions of species.

The mesopredator release hypothesis (MRH) has been suggested as a reason why many mammalian generalist mesopredators flourish and become abundant. However, the MRH has only been examined in a limited number of field studies. Some studies have argued that coyotes (Canis latrans) act as top predators in fragmented forest systems and coyote presence has a positive effect on song bird diversity and abundance by controlling mesopredator abundance. We integrated camera trap data and occupancy modeling to determine the factors that affect coyote detection probability and habitat use in a fragmented suburban landscape in central Missouri. We then examined the influence of coyote presence and other habitat variables on mesopredator detection probability and habitat use in the same system. Coyote detection was negatively related to increasing forest cover, whereas red fox (Vulpes vulpes) detection was positively related to increasing urbanization. Coyote occurrence models suggested little habitat selection, while the mesopredator occurrence models suggested an affinity for urbanization. Although there was a slight negative effect of coyote presence on site use by other mesopredators, we suggest that the smaller species are better adapted to coexisting with humans and thus have increased in abundance.

In Apr. 2010 white suckers (Catostomus commersoni) were observed spawning in the small tributary to a constructed stormwater pond on the Virginia Polytechnic Institute and State University campus. The tributary is the only direct input to the pond and provides perennial flow. We documented spawning activity, habitat characteristics, habitat use, and verified spawning success based on egg fertilization, hatching, and larval drift. The water temperature, substrate, and gradient characteristics of this stream were similar to those reports for white sucker spawning sites elsewhere in unimpaired systems. This study demonstrates that white suckers can persist in what might be considered substandard stream habitat in an urbanizing environment. By extension, other freshwater fishes may find suitable habitats in such engineered ecosystems if ecological considerations are incorporated in the design phase of planning and construction.