Measures of forest integrity often focus on only one or a small number of metrics (e.g., regeneration, soil organic layer depth). It is possible, however, to view forest integrity more holistically, using the species assemblages present as phytometers, or integrative measures of the complete set of drivers, stressors, and filters acting on the ecosystem. Thus, the species themselves express forest integrity. We collected extensive data on the overstory, understory, and groundlayer from 158 long-term vegetation monitoring plots in four U.S. national parks, within the Great Lakes basin. From these data, we calculated species richness and the modified Floristic Quality Index (mFQI), a measure of species' conservatism and habitat faithfulness. We also determined the proportion of species within categories of each of four separate ecological traits: growth form, life history, pollination mode, and nativity. In general we found lower mFQI values in parks with greater species richness. The proportions of species in categories within the life history and nativity ecological traits varied little among all four parks; proportions in categories for the growth form and pollination mode traits at Apostle Islands differed from the other parks, in having more woody species than any other growth form and more species pollinated abiotically than by other strategies. Across all four parks, our results are consistent with other assessments of species richness on islands and species richness in relation to habitat variability. Both the mFQI values and the taxa groupings in each of the four ecological traits are expected to be responsive to ongoing stressors of forest integrity. Because these techniques are both intuitive and relatively easily assessed, their application as effective gauges of change can apply not only in these four parks, but more broadly, throughout most natural areas.

Invasive Amur honeysuckle (Lonicera maackii) creates a dense shrub layer in eastern deciduous forests that negatively impacts native herbs and tree seedlings. Given the well-studied influence of habitat structure on spider abundance and guild composition, we examined the effects of this invasive shrub on spiders in forests of southwestern Ohio. Because spiders are sensitive to shrub architecture, we predicted that increased vegetative cover caused by invasion of L. maackii would increase diversity and abundance of spider taxa and guilds. We used paired plots (e.g., honeysuckle present and honeysuckle-absent) in ten deciduous forest locations to sample spiders and measured vertical cover of woody vegetation in the shrub layer. Abundance of spiders overall, spider families (Anyphaenidae, Araneidae, Salticidae, Theridiidae) and spider guilds (foliage runners, orb weavers, space web builders, stalkers), was higher in honeysuckle-present than in honeysuckle-absent plots, but diversity was not affected. Ordination of spider taxa and guilds significantly distinguished honeysuckle-present from honeysuckle-absent plots. Invasion by honeysuckle more than doubled the amount of vertical cover on honeysuckle-present plots compared to honeysuckle-absent plots. This increased vertical cover explained the significant increase in abundance of spiders and spider guilds on honeysuckle-present plots, likely because of increased complexity of vegetation. While a positive association between vegetation complexity, spider abundance, and guild structure has been documented for native habitats, our study extends this relationship to result from invasion by an exotic shrub. Because spiders are important predators in forest food webs, and their abundance is higher in areas containing honeysuckle, forests could be managed to retain some honeysuckle in the system, thereby preserving their positive effect on spider populations.

Elk (Cervus canadensis) can significantly alter plant community composition and reduce plant biodiversity, mass, seedling numbers and sapling growth. Yet, few studies have examined the interactions of reintroduced elk with woody plant communities in eastern North America. To test the hypothesis that elk herbivory would reduce woody plant diversity and recruitment and also change woody plant community composition when compared to deer, we evaluated herbivory effects of a captive elk herd and a free-roaming white-tailed deer (Odocoileus virginianus) population in Land Between the Lakes National Recreation Area in western Kentucky. Elk and deer herbivory did not differ in their effects upon overall woody plant diversity. However, elk browsing significantly altered woody plant community composition (F_1,15  =  2.27, P  =  0.005), reduced stem heights of Quercus and Cornus genera (Ps < 0.036) and reduced frequencies of Quercus, Nyssa, and Sassafras (Ps < 0.045) when compared to deer. Our results suggest elk herbivory pressure on Quercus, as well as other tree and shrub species, will affect eastern forest regeneration and thus managing the growth and distribution of reintroduced elk populations will be important for the viability of eastern and midwestern deciduous forests within restoration zones.

Noccaea caerulescens (formerly Thlaspi caerulescens, Brassicaceae) is a model species for studying the genetics and physiology of metal hyperaccumulation and is economically valuable for phytoremediation. Its growth and survival under varying natural conditions remain relatively unstudied but such information would be essential for assessing the effectiveness and potential ecological impacts of using N. caerulescens for phytoremediation. In this study, we experimentally introduced N. caerulescens seeds and seedlings to three sites with zinc- and cadmium-contaminated mine tailings in southwestern Colorado. We observed its germination, growth, and survival at three distances from the tailings (‘locations’) and with and without native vegetation removal to assess its establishment potential. Overall plant growth was slow and plants did not reach reproductive stage after three growing seasons, but plant performance did vary by site and location. High soil copper concentrations in the tailings at one site greatly reduced plant survival, whereas high plant-available zinc in the tailings increased survival and growth at the other two sites. Presence of native vegetation had a facilitative effect on early growth and survival of germinated seedlings. Our results suggest N. caerulescens is unlikely to become invasive if introduced to similar high elevation sites for phytoremediation. However, our finding that plants can survive on low-metal soils, combined with the species' high reproductive potential, warrants further research to examine its ability to establish at other field sites.

Grassland restorations are being conducted, in part, to restore habitat for declining grassland bird populations. These restorations commonly utilize both native warm-season grasses and exotic cool-season grasses in seeding mixes. While variation in community assemblage and abundance of grassland birds between these habitat types has been studied, knowledge of patterns in nest survival among warm- and cool-season grassland restorations is incomplete. We examined patterns in nest survival of grassland birds between restored warm- and cool-season grasslands in west-central Missouri. We found 35 Henslow's Sparrow (Ammodramus henslowii), 40 Dickcissel (Spiza americana), and 20 Eastern Meadowlark (Sturnella magna) nests from 2010 to 2011. Using the logistic exposure method, we estimated that the Henslow's Sparrow had high daily survival rates (0.977) across the nest period (first egg to fledging), while estimates of Dickcissell (0.947) and Eastern Meadowlark (0.961) daily nest survival were similar to previously recorded estimates. Grassland habitat type was an uninformative parameter in models of daily nest survival rates for all study species and in models of brood parasitism by Brown-headed Cowbirds (Molthrus ater) on Dickcissell nests (18% of all nests parasitized). Our findings suggest that warm- and cool-season grasslands might similarly satisfy breeding requirements for these grassland bird species.

Red-cockaded woodpeckers (Picoides borealis) in the Ocala National Forest are located near the southern edge of the species' geographic range in a region that contains the largest contiguous area of sand pine scrub habitat endemic to Florida. We examined nest site selection and nest success of the species in this unique region to determine which habitat characteristics and management activities contribute most to woodpecker productivity. We used data from a single year (2010) to assess the relative importance of forest stand features, landscape features, management activities, and spatial characteristics affecting social behavior of the birds and found fire management practices played the largest role in habitat selection, while understory characteristics were most important to reproductive success. We also used data spanning an entire decade (2001 to 2010) to assess the relative importance of landscape features, management activities, spatial characteristics affecting social behavior of the birds, and environmental factors in habitat selection and productivity. We again found the number of fire events was most influential to habitat selection, whereas the location of clusters relative to the sand pine ecotone was most influential to reproductive success. Results highlight the well-known importance of using fire to maintain quality habitat for the species but also suggest some unique aspects pertinent to managing this southern population of red-cockaded woodpeckers.

Hybrid zones, where phenotypically distinct populations interbreed, should expand or contract until reaching a balance between selection and dispersal. Few studies examine multiple contacts within one species complex to compare how their extent changes over time. Black-crested and Tufted Titmice (Baeolophus atricristatus and B. bicolor) hybridize extensively within a narrow zone in Texas and southwestern Oklahoma. In Texas, hybridization has been occurring for several thousands of years, while evidence suggests the southwestern Oklahoma contact is more recent, beginning within the past century. We quantify plumage and morphology of the two species across both the younger and older hybrid zones and compare the current and historical extent of phenotypic variation in the older Texas contact with that in the younger Oklahoma contact. Variation in plumage between species is similar in the younger and older contacts, while overlap in morphological characters is broader in the older contact. Recently and historically surveyed transects in the older zone have similar cline widths, indicating selection, at least on crest and forehead plumage, has reached equilibrium with dispersal over the time periods involved (comparing both the historically surveyed data from 1955 vs. the recently surveyed data from the 2000s in Texas). In the recently surveyed younger Oklahoma contact, cline width is narrower, indicating potential for expansion if it follows the course of the older contact. This temporal complexity should make this species complex a productive system for future work, using plumage and additional traits such as song and genetics, on the relative influences of both natural and sexual selection on the evolution of reproductive isolation.

Silver Chub (Macrhybopsis storeriana) was once a common forage fish in Lake Erie but has declined greatly since the 1950s. Identification of optimal and marginal habitats would help conserve and manage this species. We developed neural networks to use broad-scale habitat variables to predict abundance classes of Silver Chub in western Lake Erie, where its largest remaining population exists. Model performance was good, particularly for predicting locations of habitat with the potential to support the highest and lowest abundances of this species. Highest abundances are expected in waters >5 m deep; water depth and distance to coastal habitats were important model features. These models provide initial tools to help conserve this species, but their resolution can be improved with additional data and consideration of other ecological factors.

Clinch dace Chrosomus sp. cf. saylori is an undescribed species that was identified in Virginia in 1999. Due to potential threats from habitat degradation, high population fragmentation, and unknown distribution, Clinch dace is currently listed as a Federal Species of Concern and on Virginia's Wildlife Action Plan as Tier II- Very High Conservation Need. Still, a detailed description of distribution and critical habitat requirements is necessary to develop a management plan for Clinch dace. We sampled 60 locations, mostly in the upper Clinch River watershed in Virginia, to determine Clinch dace occupancy. In addition we collected data on 18 habitat variables at each location and used multivariate methods to quantify Clinch dace habitat requirements. Clinch dace were distributed in 14 locations across eight drainages of the upper Clinch River. Abundance at each location ranged from 1 to 13. Streams occupied by Clinch dace had small substrate, narrow stream width, shallow depth, and undeveloped watershed landuse. Results of this study provide evidence that Clinch dace are patchily distributed at landscape and stream scales. Further, low abundance makes the potential for population collapse an immediate concern. Future conservation efforts should be of utmost priority and include conservation of critical habitat and long-term monitoring of known populations.

We tested for diel substrate use in artificial stream experiments for six minnows: redfin shiner (Lythrurus umbratilis), silver shiner (Notropis photogenis), spotfin shiner (Cyprinella spiloptera), central stoneroller (Campostoma anomalum), striped shiner (Luxilus chrysocephalus), and bluntnose minnow (Pimephales notatus). Our experimental pools contained two of three possible substrate types (sand, cobble, and gravel) per trial, and we tested if habitat use differed in day and night observations. Over 85% of individuals and all species were observed over cobble substrate during the day, and no species occurred in higher abundances over a single substrate type at night. Fish locations during night observations were over cobble and sand or cobble and gravel. Our results suggest that minnows use coarse substrates during the day and do not have substrate preferences at night. Habitat use studies with only daytime observations of small-bodied fishes likely cannot be interpreted as complete. Further investigations of substrate use variation with 24 h observations and additional body size or life stage variation will provide species-specific habitat requirements and better understanding of stream assemblage structure.

We quantitatively sampled the threatened Inflated Heelsplitter (Potamilus inflatus) in the Amite River, Louisiana, U.S.A., and sectioned shells to study its life history, as well as electrofishing the river to determine the relative abundance of its host fish. Inflated Heelsplitters are currently limited to a 40 km stretch of the Amite River, east of Baton Rouge, although they are also found in two rivers in northwest Alabama. Densities averaged 0.1 m⁻², with an aggregated dispersion pattern, making them the sixth most abundant species out of 15 species found in quantitative samples. Inflated Heelsplitters mature after 1 y, live for 8 y, and have a rapid growth rate (K  =  0.69/y). The average life span of eight other mussels in the Amite River is 24 y, and average age at maturity is 3.6 y. Sexual dimorphism may occur in Inflated Heelsplitters as it does in the related Bluefers (Potamilus purpuratus), with males reaching larger sizes. Inflated Heelsplitters have an opportunistic life history strategy (Haag, 2012), which may be well adapted to flashy rivers and low population densities. It is however a long term brooder, which has been linked to higher chances of extinction (Vaughn, 2012). The Freshwater Drum (Aplodinotus grunniens), the fish host of the Inflated Heelsplitter, was the 17th most abundant out of 44 fish species sampled in the Amite River. Its relatively rare host fish, anthropomorphic disturbances from upstream gravel mining, or increased urbanization of the watershed may be important in explaining the threatened status of the Inflated Heelsplitter.

Freshwater gastropods represent common and important members of aquatic ecosystems, but emerging chemical contaminants may challenge gastropod fitness. As the use of nanosilver (n-Ag) increases, the potentially adverse effects of n-Ag on aquatic ecosystems remain largely unknown. In aquatic ecosystems, we hypothesized that n-Ag at trace concentrations may affect the ability of organisms to sense predation by interfering with chemoreception. We performed a microcosm experiment to assess the freshwater gastropod, Physa acuta, to detect and respond to natural predator cue derived from pumpkinseed sunfish (Lepomis gibbosus), at environmentally relevant nominal n-Ag concentrations over 24 h. For the first 6 h exposure, gastropod predator avoidance behavior measured 30–47% less in treatments with environmentally relevant n-Ag concentrations compared to treatments without n-Ag. Regardless of predator cue presence or absence, the proportion of gastropods occupying near surface habitat in 30 µg/liter n-Ag appeared 20–26% greater relative to no n-Ag treatments for the first six exposure hours, indicating contaminant avoidance behavior. These results suggest that nonlethal concentrations of emerging contaminants affect animal behaviors. These behaviors, in turn, may have consequences for species interactions and ecosystems. Thus, future research efforts need to address the ecology in ecotoxicology by understanding how environmentally relevant concentrations of emerging contaminants may adversely affect the chemoreception, growth, and fecundity of organisms essential to the structure and function of freshwater ecosystems.

The Texas pocket gopher (Geomys personatus) occurs throughout much of southern coastal Texas. Recent genetic studies clarified phylogenetic relationships within the genus Geomys, but the geographic distribution of lineages of G. personatus in southern Texas remains uncertain. We sampled G. personatus in southern Texas and analyzed cranial morphology and DNA sequence data from the mitochondrial cytochrome b gene. Morphology provided weak discriminatory power for the identification of subspecies. Pocket gophers showed high genetic structure in the region, with low levels of haplotype diversity within sites and few shared haplotypes among sites. Phylogenetic analyses revealed Geomys trapped in mainland Nueces County and Flour Bluff clustered with GenBank sequences of G. p. maritimus. Padre Island samples formed a well-defined subcluster, similar to but distinct from G. p. personatus and G. p. megapotamus sequences. Samples from Kleberg County formed a separate clade, consistently outside of G. personatus; Kimura 2 parameter sequence divergence between Kleberg County and G. personatus was >0.12, and Kleberg County samples were more similar to G. texensis (sequence divergence 0.06–0.08). The Kleberg County samples appear to represent a previously undetected cryptic lineage.

The red tubular flowers of Penstemon eatonii (Plantaginaceae) typify the classic pollination syndrome for hummingbirds. Bees are thought to diminish its seed siring potential, but we found that foraging female generalist bees (Apis, Anthophora) deposited substantial amounts of conspecific pollen on P. eatonii stigmas. In the absence of hummingbirds, bee pollination of cultivated P. eatonii annually generated massive seed yields from a 1.5 ha field. Most penstemons with red tubular flowers like P. eatonii present a symmetrically flared floral opening that facilitates landing by foraging bees. Derived floral traits that attract and position nectar-foraging hummingbirds for efficient pollen export (red deeply tubular flowers secreting abundant dilute nectar) need not compromise pollination and seed production that result from visitation by generalist bees seeking pollen and/or nectar.

There is a paucity of information regarding the feeding habits of the Southern flying squirrel Glaucomys volans. We investigated dietary preference of G. volans by computing the mean daily rate of ingested energy for five food resources: fruits of flowering dogwood Cornus florida; acorns of white oak Quercus alba, water oak Q. nigra, and black oak Q. velutina; and nuts of pignut hickory Carya glabra. The preferred food of G. volans was Q. alba, constituting 49.7% of their mean daily diet. Q. velutina and Q. nigra were ranked next in dietary preference. The least preferred food types were the fruits of C. florida, and nuts of C. glabra. There was no significant difference when comparing sex with food preference and sex with caloric intake.

A large emergence of bats from a roost tree or more commonly a cave, provide birds of prey, especially owls, with an improved opportunity to capture bats. Away from these concentrated bat communities, bats are thought to make up an insignificant portion of owl diets. However, little research has investigated if bats perceive owls as a potential predatory threat. We conducted acoustic bat surveys to assess if bat activity was altered by the presence of owl calls or ambient nocturnal noise. Our surveys found no difference in the level of bat activity recorded before or during broadcasted owl calls or nocturnal noise. It is possible bats do not respond to calling owls because bats do not perceive owls as a threat. Additional studies may elucidate the relationship (if any) between bats and owls.