We sampled fishes and aquatic insects monthly (Jun.–Sept. 2002) from intermittent tributaries of the Alum Fork of the Saline River (Arkansas, U.S.A.) to quantify the response of fish and aquatic insect assemblage properties to seasonal desiccation and habitat fragmentation. We collected a total of 4219 individuals, representing 18 species of fishes and 27 families of aquatic insects. Changes in the composition of fish assemblages were significantly related to temporal variability in pool volume and location in the watershed. Smaller, upstream pools varied in volume more than downstream pools. Fish assemblages were significantly more similar through summer in downstream, larger pool habitats. Changes in the composition of aquatic insect families were related to variation in water quality conditions. Highly eutrophied sites were typically dominated by midge larvae (Chironomidae), resulting in highly similar assemblages over time. Our results support findings at larger space and time scales and call attention to the importance of rapid changes in habitat quality, size and connectivity on stream communities.

Few studies have used radiotelemetry to focus directly on the diel behavior of turtles. We used radiotelemetry to relocate 10 Stripe-necked Musk Turtles (Sternotherus minor peltifer) every 2 h over a 24 h cycle in Middle Tennessee. Movements during the 24 h cycle were monitored on seven occasions between 27 Jul. and 4 Nov. 2004. Sternotherus minor peltifer were often inactive and remained sedentary throughout a 24 h cycle; 87% of the total relocations revealed no movement. Overall, S. m. peltifer's diel movement behavior was restricted to evening and nocturnal hours. Frequency data suggested a uni-modal distribution of movement during evening and midnight periods (1700–0159 h). Similarly, the mean distance traveled showed a uni-modal distribution with a peak in the evening period of a 24 h cycle. Based on the data set with only light and dark categories, males were found to move more frequently in daylight relative to females. A decrease in movement (frequency and distance) occurred with the changing of the seasons from summer to winter. Probably due to temperature change, nocturnal and crepuscular behaviors were highest in Jul. and Aug., while during the autumn months, there was little preference for daylight or darkness. This phenomenon has been reported in several Sternotherus species; but, to our knowledge, this is the first report for S. minor.

We examined life history traits of Phoxinus tennesseensis (Tennessee dace), a globally vulnerable (G3) upper Tennessee River drainage endemic, in 2 populations in Northeast Tennessee. The spawning season lasted from Apr. to Jun. Spawning occurred over the nests of Semotilus atromaculatus (creek chub) and Campostoma anomalum (central stoneroller), where large spawning aggregations of dace gathered over host species nests. Phoxinus tennesseensis populations have 4 size classes that are indicators of age classes. The mean life span of P. tennesseensis is about 2 y with 1st y fish constituting a majority of the population. Fecundity samples indicate that females produce 398 to 721 ova that were 0.9 to 1.5 mm in diameter. Phoxinus tennesseensis has the lowest fecundity when compared to closely related congeners and inhabits the smallest headwater streams that frequently experience reduced or no-flow conditions. These characteristics probably contribute to its very limited distribution and small population sizes, and make the few remaining populations very vulnerable to environmental disturbances.

The bluemask darter Etheostoma (Doration) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters (Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish <3 y old. Some age-one individuals were sexually mature, but the majority of the reproductive population was comprised of older fish. Differences in age-class structure among years reflected variable year-class strength in the Collins River that seemed related to summer discharge. Male and female growth rates differed significantly (P < 0.05); males were typically larger than females of the same age after the first growing season and the majority of age-three individuals were males. Growth rates in the Collins and Rocky Rivers were similar for each sex (P > 0.05). In both rivers, females were more abundant than males.

Management of invasive species often targets a particular life stage in structured populations. Evaluating the success of management requires measuring the survivorship and reproductive success of the targeted stage class, as well as assessing the possibility for increased fitness in the non-targeted stage class due to a release from density dependence. Management of the invasive biennial, Alliaria petiolata (garlic mustard) focuses on removing adults by pulling or clipping and is applied early or late in the reproductive season. We evaluated the effectiveness of different management types (unmanaged, clipped, pulled) and timing (early or late) on survival and fitness of targeted adult plants and non-targeted, co-occurring juveniles. Viable seeds were produced by adults that were unmanaged, pulled early in the season and clipped at midheight early in the season. Unmanaged and pulled adults produced significantly more seeds than clipped plants; unmanaged plants produced seeds that were significantly heavier than seeds from clipped or pulled plants. Germination was lower for seeds from pulled plants than for seeds from unmanaged or clipped plants. The clipping treatment was most successful at reducing fecundity, but also resulted in the highest survivorship of co-occurring juveniles. Our study highlights the necessity of examining fitness of plants in the non-targeted life stage in order to fully evaluate the effectiveness of different management techniques. These results should be applicable to management of other stage-structured invasive species.

The crayfish Orconectes eupunctus is endemic to the Spring and Eleven Point rivers of Arkansas and Missouri, and appears to have been displaced from a portion of its range by the recently introduced crayfish O. neglectus. Life history can be a factor in crayfish species displacements as earlier reproduction or rapid juvenile growth may provide size advantages in competitive interactions, while higher fecundity might permit an invading species to out reproduce a native. We conducted a comparative study to determine if life history differences exist between O. neglectus and O. eupunctus that could contribute to the displacement of O. eupunctus. Crayfish were collected at three sites (each species alone and both species together) monthly from Jul. 2005 through Dec. 2006 by kick-seining. Timing of reproductive events was recorded, fecundity was evaluated through egg counts, and juvenile growth rates were examined using length-frequency histograms. Sex ratios, length-weight relationships, and adult size structure were also documented. Timing of reproductive events was synchronous between species, with males molting to Form I in Sep.–Oct., females producing glair in Nov.–Dec., and oviposition in Mar.–Apr. Orconectes neglectus females carried significantly more eggs than O. eupunctus females, but a greater proportion of O. eupunctus females were ovigerous than O. neglectus. Juvenile crayfish of both species recruited to the population in May and achieved similar sizes by the end of the growing season. Orconectes eupunctus adults in the presence of O. neglectus were smaller than both O. neglectus adults and O. eupunctus isolated from the introduced species. Both species showed a typical annual pattern in sex ratios for Orconectes spp. crayfishes, with male-skewed sex ratios when females were ovigerous in the spring and female-skewed sex ratios in other seasons. The sex ratio of O. eupunctus in the presence of O. neglectus was male depleted relative to both O. neglectus and O. eupunctus alone. For both O. neglectus and O. eupunctus, male crayfish weighed more than female crayfish, but no significant differences existed between the species within the same sex. Results of this study will complement and inform further research into a potential mechanism for the apparent displacement of O. eupunctus by O. neglectus, and also help document the under-studied life histories of crayfishes endemic to the southeastern United States.

White-tailed deer in the agricultural Midwest are limited during fall and winter to areas of combined food and cover, usually remnant forests in a matrix of agriculture. During this period, tree seedlings may be at higher risk to herbivory because herbaceous and agricultural foods are unavailable and deer are concentrated in forest patches. We monitored planted swamp white oak seedlings to examine how autumnal herbivory affected nutrient loss and survival. Herbivory during this season resulted in significant losses of nitrogen and phosphorous stored within the stem, with nitrogen stores significantly reduced throughout the seedling's tissues. Nutrient loss due to deer herbivory has the potential to prevent seedlings from reaching reproductive maturity, altering future successional paths and affecting forest composition. To alleviate herbivory pressure, forested refuges may benefit from hunting or sharpshooting, with treatments coinciding with peak crop harvest activity.

We examined the diet of big brown bats (Eptesicus fuscus) during an emergence of 17-y cicadas (Magicicada spp.) in May and Jun. of 2004 in Indiana. We collected guano from a maternity colony of big brown bats and compared the diet during the cicada emergence to the diet during the same period of a non-cicada year. In contrast to previous studies, homopterans (predominantly 17-y cicadas) were a common food item (22.9–23.6% volume) during the peak of cicada abundance. Scarabaeidae (13.8–48.5%), Carabidae (7.3–36.9%) and hemipterans (19.4–29.3%) were also common prey items during the cicada emergence. Although periodical cicadas constituted a fair amount of the diet during the emergence, the dietary diversity of big brown bats during the emergence was similar to that of non-cicada years. Our results demonstrate that big brown bats forage on 17-y cicadas during a cicada emergence. However, despite the superabundance of cicadas, big brown bats do not specialize on cicadas to the relative exclusion of other prey types.

Monitoring animal populations is critical for the development of successful management strategies. This is especially important for populations that have been reintroduced to historic habitats, such as river otters (Lontra canadensis), which were reintroduced to Missouri during the 1980s and 1990s. We measured river otter relative abundance in southern Missouri using seasonal bridge-sign surveys on 15 study areas from 1996 to 1999. Otter sign was detected at 63% of the bridges during fall surveys and 82% of the bridges during spring surveys. Relative abundance during the fall 1996 survey (the only pre-harvest survey) was significantly higher (P  =  0.0014) than during the fall 1997 and fall 1998 surveys that followed the institution of a legal trapping season. Relative abundance based on spring surveys were not significantly different (P  =  0.196) over the 3 y. Repeat surveys conducted in the same year did not result in significantly different relative abundance in either fall 1997 (P  =  0.13) or spring 1997 (P  =  0.27). These results were similar to catch per unit effort (CPUE) estimates, but not entirely consistent. We recommend that managers conduct bridge-sign surveys during the same season and employ at least one other direct measure of the relative abundance (CPUE or mark-recapture) in order to monitor long-term relative abundance of otters.

Rafinesque's big-eared bats (Corynorhinus rafinesquii) and southeastern myotis (Myotis austroriparius) are uncommon throughout their range and are listed (informally) by the U.S. Fish and Wildlife Service as species of management concern. Much of the decline in numbers of these species can be linked to a loss of bottomland hardwood forests throughout their range, resulting in a loss of natural roost structures in many areas. We characterized day roosts of both species and determined differences in characteristics of roost trees in western Tennessee. Radio transmitters were attached to adult females of both species to aid in locating new roosts. Thirty-one roost trees were identified, with most (93.5%) being large hollow water tupelos (Nyssa aquatica). Only two roost trees were used by both species during the survey period and no simultaneous roosting was documented. Roost trees in our study typically had triangular-shaped basal openings and large diameters (129.2 ± 7.3 cm). A significant difference (P < 0.05) in roost-tree diameter was observed between trees used by the two bat species. Our study is the first to compare characteristics of tree roosts of sympatric populations of Rafinesque's big-eared bats and southeastern myotis. Results suggest that these species may have different preferences for roost trees.

We examined attributes of 45 roost sites used by 17 adult male evening bats (Nycticeius humeralis) in a diverse forested landscape within the Ouachita Mountains, Arkansas. Bats roosted in a diverse array of substrates, including live or dead Pinus echinata ≥15 cm diam at breast height (29% of roosts) and small (<10 cm) understory or midstory hardwoods (20% of roosts). Sixty-three percent of roosts were in snags, 29% in live trees and 8% were on or near the ground. One roost was located in tree foliage, one in leaf litter and one was underground in what appeared to be a small-mammal burrow. Logistic regression models indicated that sites surrounding roosts were more likely to have fewer stumps and more hardwoods snags ≥10 cm diam at breast height than random sites. At the forest-stand level, all roosts were in stands with a mature (>50 y old) overstory. Twenty-six roosts (58%) were in stands that had undergone partial harvest, midstory removal and burning within the last 6 y, but 13 (50%) of those roosts were in unharvested inclusions (greenbelts) retained along stream drains within these stands; thus, 71% of all roosts were in unharvested patches of forest. Male evening bats were flexible in their roost selection, using a range of tree types (both live and dead), sizes and forest habitats. Possibly because cooler sites allow more frequent use of torpor during summer, they often roosted in small understory snags and in closed-canopy forest stands where these small snags were abundant. However, they also roosted in partially harvested portions of stands where a mature overstory was retained. Our results suggest that management intended to provide optimal roosting sites for females may not be applicable to male evening bats.

Rafinesque's big-eared bats (Corynorhinus rafinesquii) use bridges as day roosts in parts of their range, but information on bridge use across their range is lacking. From May to Aug. 2002 we surveyed 1129 bridges (12.5%) within all 46 counties of South Carolina to determine use and selection of bridges as day roosts by big-eared bats and to document their distribution across the state. During summer 2003, we visited 235 bridges in previously occupied areas of the state to evaluate short-term fidelity to bridge roosts. We found colonies and solitary big-eared bats beneath 38 bridges in 2002 and 54 bridges in 2003. Construction type and size of bridges strongly influenced use in both years; bats selected large, concrete girder bridges and avoided flat-bottomed slab bridges. The majority of occupied bridges (94.7%) were in the Upper and Lower Coastal Plains, but a few bridges (5.3%) were located in the Piedmont. Rafinesque's big-eared bats were absent beneath bridges in the Blue Ridge Mountains. We established new records of occurrence for 10 counties. In the Coastal Plains, big-eared bats exhibited a high degree of short-term fidelity to roosts in highway bridges. For bridges that were occupied at least once, mean frequency of use was 65.9%. Probability of finding bats under a bridge ranged from 0.46 to 0.73 depending on whether the bridge was occupied in the previous year. Thus, bridges should be inspected three to five times in a given year to determine whether they are being used. Regional bridge roost surveys may be a good method for determining the distribution of C. rafinesquii, particularly in the Coastal Plains, and protection of suitable bridges may be a viable conservation strategy where natural roost sites are limited.

Bottomland forests in the eastern United States are used by bat populations for both roosting and foraging. To quantify habitat characteristics important to bat presence in the Mississippi River alluvial valley, we measured forest habitat variables and related them to bat captures obtained in six management areas located near Jonesboro, Arkansas. Forest measurements included species composition, stem count, canopy height, basal area, canopy coverage and percent vegetative ground coverage for trees found in 120 0.03-ha circular plots from 12 bat capture sites. Principal component analysis was conducted on habitat data, and compared to bat captures by use of multiple regression analysis. Interaction effects due to the nested structure of the sampling design were measured with mixed linear models. We found significant correlations between total bat captures, composed of all captures for eight species and forests of high stem count and vegetative ground cover. Mixed model analysis revealed that Rafinesque's big-eared bats (Corynorhinus rafinesquii) were more likely to be captured at dry corridor sites than corridors over water, where as regression analysis revealed a significant (P  =  0.016) relationship between southeastern myotis and percent oaks.

Recently, greater attention has been given to the potential keystone interaction between cavity excavators and the community of animals that use cavities. However, most research has focused on avian use of cavities in the breeding season, with little attention given to other cavity using guilds or cavity use during the non-breeding season. Furthermore, most breeding season studies were in unburned forests containing a mix of conifer and deciduous trees with much less attention given to cavity rich post-burn habitats. The objective of this study was to examine cavity use during the breeding and non-breeding seasons in old-burned ponderosa pine forests in the Black Hills, South Dakota. One hundred seventy nine active cavity nests of nine cavity nesting species were monitored between 2002–2005. We examined the contents of each cavity during the breeding season and twice during each non-breeding season (fall, winter, spring) each year. Additionally, we conducted vegetative surveys to determine the microhabitat variables that might influence the occupancy of cavities in the breeding season. Binomial logistic regression with AIC model selection criteria were used to model breeding season cavity reuse for the three most common cavity excavator species, Lewis's Woodpeckers (Melanerpes lewis), Red-headed Woodpeckers (M. erythrocephalus) and Northern Flickers (Colaptes auratus). All three species reused old cavities most recently used by conspecifics for breeding; snag density (dbh > 23 cm) and cavity height consistently influenced reuse of cavities for all three species. In the non-breeding season the cavities of these same three species were all commonly used, but Northern Flicker cavities contained the greatest diversity of secondary cavity users. We speculate that Northern Flicker cavities may have been used more frequently in the non-breeding season because of their lower cavity height compared to other similar sized cavities.

Phalaris arundinacea L. (reed canarygrass) is an aggressive graminoid species that invades wetlands in much of the northern United States. In areas previously used for agriculture and other recently disturbed habitats, P. arundinacea out-competes the native flora and creates monocultures, which reduce biodiversity and alter ecosystem functioning. Much research has focused on the growth response of P. arundinacea to varying abiotic and biotic conditions in the lab or under controlled field conditions, but few studies have examined if these results are congruent with what is observed in natural settings. We examined the relationship between P. arundinacea abundance and soil nutrient characteristics at Glacial Park, USA, a conservation area in northeastern Illinois. We found significant positive relationships between P. arundinacea abundance and total inorganic nitrogen, calcium and cation exchange capacity in the soil. These results are consistent with controlled experiments showing increased P. arundinacea growth in nitrogen-rich soil, and also suggest that calcium may influence P. arundinacea abundance in restored areas in the Midwest.

Northern white cedar (Thuja occidentalis L.) stands throughout the upper Midwestern United States have failed to recruit individuals to the canopy consistently for several decades. To examine local and landscape factors that influence cedar regeneration we recorded the abundance of cedar seedlings and saplings in 24 lowland cedar stands in the Chequamegon-Nicolet National Forest, Wisconsin, during summer 2001. Cedar seedlings (height <22 cm) were common (median  =  1800 ha⁻¹), but the largest size class (height ≥100 cm) was extremely rare (∼1 ha⁻¹) and heavily browsed. We used information-theoretic model averaging of linear mixed-effects models to identify local and landscape variables important for predicting the density of seedlings and saplings. The density of newly germinated seedlings was higher along transects farther from roads and with more mature cedar. Large seedling and small sapling densities were higher along transects with open canopies located in landscapes with a higher ratio of deciduous to coniferous forest. Increased edge-to-area ratios of cedar stands and edge density of the surrounding forest were associated with lower densities of large seedlings and small saplings, respectively. Results indicated a strong demographic effect with the density of large size classes being strongly dependent on the density of smaller size classes. Because the landscape factors considered are linked to browsing intensity, a reduction in deer (Odocoileus virginianus Zimmermann) density coupled with landscape-sensitive forest management may help to foster cedar regeneration in northern Wisconsin.

Over the last five decades, the floodplain forests along the Lower Wisconsin River have experienced several events capable of shifting forest structure and composition, including river regulation, Dutch elm disease and increased levels of herbivory. This study analyzes changes in the structure and composition of the vegetation in the floodplain forests over the previous 50 y by comparing forest survey data collected in 2001 with data collected on the same sites by John Curtis in the 1950s. The results suggest that the forests are shifting to a previously unrecorded later successional stage, dominated increasingly by silver maple, hackberry and bitternut hickory, a possible result of river regulation. Early-successional stages, particularly those dominated by black willow and cottonwood, are disappearing. Disturbances, such as timber harvests, may be increasing the rate of this transition. Further, the forests have shown a large increase in the dominance of two thorny shrubs, prickly ash and European buckthorn, in the understory, suggesting browsing pressure may be affecting regeneration. Analysis of the ground layer parallels these findings, showing an increase in species more typical of higher elevations in the floodplain and mesic forests, as well as invasive species and dominance by several species less palatable to deer.

A transgenic variety (red glofish) of the aquarium fish, zebra danio (Danio rerio) and wildtype zebra danios were exposed to the natural climate of north Texas in four, outside, 10,000-L microcosms during the winter of 2004–2005. At least 13 of 68 fish survived at temperatures as low as 7.5 C; however, none survived a 4 d exposure to 4 C following a cold front. These field results corroborate laboratory findings that the lowest temperature that these two varieties of D. rerio can survive is about 5 C.