Showing papers in "American Midland Naturalist in 2006"

Impacts of Channelization on Stream Habitats and Associated Fish Assemblages in East Central Indiana

Abstract: The objective of this study was to determine the relationship between fish assemblage and habitat in streams dominated by an agricultural landscape. Fishes from 20 natural and 20 channelized streams were sampled using electrofishing gear in east central Indiana. Streams that had been channelized had a lower quality fish assemblage when compared to natural streams as measured by the Indiana V. Eastern Corn Belt Plain Index of Biotic Integrity (IBI). Stream habitat was evaluated using the Ohio EPA Qualitative Habitat Evaluation Index (QHEI), which indicated that channelized streams had lower quality primarily due to a loss of heterogeneous habitat. Pearson correlation analysis relating IBI and QHEI was positive and significant and demonstrated that a reduction in riffle and pool areas associated with channelization was the most significant factor influencing the fish assemblage. Furthermore, species lost when streams were channelized were predictable and often represented environmentally sensitive ...

Invasion of Downy Brome (Bromus tectorum L.) Causes Rapid Changes in the Nitrogen Cycle

Abstract: Invasion of exotic species threatens the stability of ecosystems and is regarded as a significant component of global ecological change. One of the most successful invasive species of the intermountain west of the United States is Bromus tectorum L. (downy brome)—an annual Eurasian grass that was first observed in North America in the late 1800s in areas of Washington, Oregon and Utah and now covers ca. 40,000,000 ha. The prevalence of B. tectorum raises concerns regarding its potential effects on ecosystem structure and function. In this study we investigated the effects of invasion of B. tectorum on an ungrazed grassland in Canyonlands National Park, Utah. Because the invasion occurred on previously established study transects, we were able to assess the short-term effects of an invasion with a known entry date. We conducted long-term soil incubations in the laboratory to obtain data on cumulative nitrogen mineralization which was used to calculate the size of the labile pool of soil nitrogen. ...

Extirpation of freshwater mussels (Bivalvia: Unionidae) following the invasion of dreissenid mussels in an interconnecting river of the Laurentian Great Lakes

Abstract: Previous (1992–1994) surveys for native freshwater mussels (Unionidae) along main channels of the Detroit River showed that unionids had been extirpated from all but four sites in the upper reaches of the river due to impacts of dreissenid mussels (Dreissena polymorpha and D. bugensis). These four sites were surveyed again in 1998 using the same sampling method (timed-random searches) to determine if they may serve as “refugia” where unionids and dreissenids co-exist. Two additional sites were sampled using additional methods (excavated-quadrat and line-transect searches) for comparison with unpublished data collected in 1987 and 1990. A total of four individuals of four species (Actinonaias ligamentina, Cyclonaias tuberculata, Lasmigona complanata and Pleurobema sintoxia) were found by timed-random searches at four sites in 1998 compared to 720 individuals of 24 species in 1992 and 39 individuals of 13 species in 1994. Excavated-quadrat and line-transect searches at the two additional sites yiel...

Effects of White-tailed Deer on Tsuga canadensis Regeneration: Evidence of Microsites as Refugia from Browsing

Abstract: Both herbivory and windthrow disturbances have individually been shown to dramatically alter the structure and composition of forest communities; however, the interaction of these two factors has scarcely been examined. Windthrow disturbance creates microsites such as fallen logs and treefall mounds and pits that may hinder movement and limit visibility of large mammals, thereby reducing the impact of browsing by white-tailed deer. In an old growth Pennsylvania forest that was severely wind-damaged in 1985, a previous study based on sampling in 1994 demonstrated reduced browsing and greater Tsuga canadensis (L.) Carr seedling density on treefall mounds (Long et al., 1998). In this study we surveyed mounds to see if they continue to be effective browsing refugia 9 y later. We also determined whether other types of microsites and nearby microsites provide protection from browsing and tested for an associational density refuge, whereby seedlings of a preferred species are less browsed when surrounde...

Variation in the Echolocation Calls of Little Brown Bats (Myotis lucifugus) in Response to Different Habitats

Abstract: Among different bat species, echolocation call structure varies predictably according to habitat use. Much of this interspecific variation in echolocation calls reflects the physical constraints of sound propagation and echo formation in open versus spatially complex habitats. Bats must use calls that are suitable for detecting obstacles and prey in a particular setting; thus, bats that use similar habitats and catch similar prey produce similar calls. The same can be true for variation in echolocation calls within a single species that uses a variety of habitats. I recorded the echolocation calls and habitat use of a habitat generalist bat, Myotis lucifugus in order to determine whether the echolocation calls of M. lucifugus vary predictably across habitats, and if call variation is the result of individual flexibility in habitat use and echolocation behavior. I found that M. lucifugus used calls with higher frequencies, shorter durations and steeper frequency modulation in cluttered habitats than in open habitats. This type of call is consistent with a short-range target-detection strategy whereas the lower frequencies, longer call durations and shallower frequency modulation of bats in open habitats are consistent with longer-range target detection strategies. Furthermore, radiotelemetry indicated that individuals routinely foraged in different habitats. Taken together, these results suggest that call variation across habitats is the result of individual plasticity in echolocation behavior.

Swine activity alters invertebrate and microbial communities in a coastal plain watershed

Abstract: Swine (Sus scrofa Linnaeus) are an invasive species with a negative impact on native terrestrial plant and animal diversity. Further, in its native range, excessive population size has been perceived as a potential problem. The effects of swine on aquatic organisms remain poorly documented. We investigated the effect of an unmanaged population of feral and free ranging swine upon aquatic habitat, invertebrates and microbes in a coastal plain stream in Louisiana. Sampling was conducted twice yearly, spring and fall, from August 2002 through April 2004, at five sites within the Mill Creek watershed. We measured stream characteristics, carbon and nitrogen, biochemical oxygen demand, fecal coliform counts and heterotrophic plate counts. We collected invertebrates from woody debris, microbes from the water column and identified both to the lowest practical taxon. Invertebrate, microbial, habitat and swine relationships were assessed with detrended and canonical correspondence analysis. Swine activity did not appear to alter stream habitats. However, swine changed the microbial taxonomic composition in the stream increasing pathogens. Swine also appeared to have a positive relationship with gastropods (snails) and a negative relationship with collecting and scraping (predominantly insect) taxa in the streams. We suggest the decline of scraper taxa may be related to the changes in microbial composition. Shifts in the invertebrate community can impact other organisms in the ecosystem, and the full extent of swine impacts on other aquatic organisms may also be negative.

Fire Regime of an Ozark Wilderness Area, Arkansas

Abstract: Many of the present day issues associated with fire management in wilderness areas are addressed by studying past interactions among fire, humans, vegetation and climate. In this paper we describe three centuries of the fire regime in the Lower Buffalo River Wilderness Area, Arkansas, USA. We reconstructed fire events from 159 tree-ring dated fire scars on 26 shortleaf pine (Pinus echinata Mill.) remnants and live trees. During the late-17th Century and early 18th Century the mean fire return interval (MFI) was 7.7 y. Fire frequency increased abruptly circa 1820 with fires burning every 2 y on average until 1920. The number of fires decreased during the 1900s as cultural values changed to favor fire suppression over multiple-use burning. Analyses of the influence of human ignitions and drought on the fire regime resulted in two important findings: (1) that fire frequency was positively correlated to human population density up to 1920 and (2) the influence of drought seemed to be masked by freque...

Characteristics of Summer and Winter Roost Trees Used by Evening Bats (Nycticeius humeralis) in Southwestern Missouri

Abstract: We radio-tracked 13 evening bats (Nycticeius humeralis) to 34 trees during the summer of 2003 and 10 evening bats to 29 trees during the winters of 2003 and 2004. We captured males in every month of the year and provide evidence suggesting that females are also year-round residents of southwestern Missouri. These captures extend the known winter range of N. humeralis at least 110 km northeast. Evening bats selected trees in late stages of decay during the summer, but during the winter they selected a higher proportion of live trees. Comparisons of summer and winter trees suggest that habitat characteristics are more important than tree characteristics in explaining variation between roosts used in the two seasons. Winter roost trees were located in areas with lower average tree height and higher densities of trees. Those attributes would likely cause problems with clutter when leaves are on the trees during summer.

Dynamics of Epikarst Communities: Microgeographic Pattern and Environmental Determinants of Epikarst Copepods in Organ Cave, West Virginia

Abstract: The copepod community occurring in the uppermost part of karst was investigated by collecting animals from 13 ceiling drips in Organ Cave, West Virginia, over a 30 d period. A total of 444 copepods belonging to six genera and ten species were found. There was considerable heterogeneity, both spatially and temporally. Among physical parameters (oxygen, drip rate, conductivity, temperature, pH, ceiling thickness and redox), overall abundance was strongly influenced by drip rate. Community composition, analyzed by Canonical Correspondence Analysis, was correlated with drip rate, oxygen and ceiling thickness. Community similarity, as measured by Jaccard index, declined with geographic distance, but after a distance of several hundred meters, the average similarity and range of values increased, as “new” communities appeared. The overall pattern appears to be a relatively fine-scale patchwork of communities at a scale of hundred or so meters. The hotbed of copepod diversity in caves is the epikarst, n...

Distribution of the Imperiled Williams' Crayfish (Orconectes williamsi) in the White River Drainage of Missouri: Associations with Multi-scale Environmental Variables

Abstract: The imperiled crayfish Orconectes williamsi is found only in the upper White River drainage in Missouri and Arkansas, and is known from only nine localities in four Missouri counties. Its distribution has never been thoroughly assessed. Knowledge of distribution and habitat associations is essential to conservation and management of rare species. Our major objectives were to estimate the distribution of O. williamsi in Missouri streams and identify associations between this crayfish's presence and selected multi-scale environmental variables. We used a probabilistic method and stratified (by stream order) random design to survey 50 of 223 total stream segments in the drainage during 2002 and 2003. We sampled 21 additional segments postsurvey (2004 and 2005). This crayfish was detected at an overall rate of 0.34 (±0.12, 95% confidence interval), and at a total of 27 sites, but we failed to collect it at two historical sites. Many stream segments harboring O. williamsi were determined to be effecti...

Expansion of Round Goby in the Illinois Waterway

Abstract: Round goby Neogobius melanostomus is expanding its range within Illinois. Prior to 2004, the round goby existed primarily in the Lake Michigan waters of Illinois and was slowly moving inland via the Illinois Waterway. Two fish community monitoring programs, administered by the Illinois Natural History Survey's Illinois River Biological Station, have detected this fish species as it further expanded its range in the Waterway. Although little is known how this non-native benthic fish could threaten ecosystems in Illinois, the rate of invasion appears to be quickening.

A 3-decade dearth of deer (Odocoileus virginianus) in a wolf (Canis lupus)-dominated ecosystem

Abstract: Some 30 y after wolves (Canis lupus) were implicated in decimating wintering white-tailed deer (Odocoileus virginianus) in a 3000-km2 area of northeastern Minnesota, wintering deer still have not recolonized the area. From 1976 to 2004, we aerially radio-tracked wolves there during 250 h and recorded 2 deer (in 1985 and 2000) killed or eaten by wolves during February and March. We observed no other deer or deer sign, but regularly observed deer, deer sign and wolf-killed deer in adjacent wolf-pack territories. Although habitat in the study area generally remains poor, some regeneration has taken place, and deer have increased adjacent to the area. However, wolf numbers have persisted by preying on moose (Alces alces). We could detect no reason other than wolf predation and deer migration traditions for why wintering deer have not recolonized the area.

Community Composition and Structural Changes in a Managed Illinois Ozark Hills Forest

Abstract: Forest stand dynamics were evaluated in a previously managed Quercus-Carya-dominated forest inventoried in 1980 and 2000, a period during which all active forest management was suspended and fire suppression was complete. The diameter distribution superficially resembled a stable unevenaged structure. Over the course of the study, smaller diameter classes were increasingly dominated by shade tolerant species Acer saccharum and Fagus grandifolia across all landscape positions. Diameter distribution changes varied among Quercus species with Q. alba and Q. rubra basal area increasing 63 and 45%, respectively, and Q. velutina decreasing 25% in the >43.2 cm size class. Combined Q. alba, Q. rubra and Q. velutina density decreased 56% in the <27.9 cm size classes. Transition towards a mesophyte-dominated forest is occurring across all positions in this topographically-diverse landscape, although more slowly on the drier, less productive aspects and slope positions. These changes are comparable to those ...

Recovery of Aquatic Macroinvertebrate Communities from Drought in Georgia Piedmont Headwater Streams

Abstract: Abstract.—Drought is an important disturbance in stream ecosystems. From 1998–2002 Georgia suffered a major drought, causing many headwater streams to experience reduced flows or to dry completely. Six headwater streams in the Georgia Piedmont were selected and paired based on similarities in substrate structure (sand, bedrock or gravel substrate). Each pair consisted of a stream that dried completely during the drought and one that retained at least some surface water. Riffles were sampled with a core sampler, runs and pools were sampled with a Hess sampler and wood was sampled by randomly collecting pieces of at least 1 cm diameter. Samples were collected within 15 d of reflooding, then after 45, 75, 165, 255, 345 and 435 d. Cluster analyses were used to assess the relative effects of drought history (dried or residual water), stream condition and temporal change. In terms of drought recovery, all streams followed the same pattern of recovery, with a rapid recolonization period following the on...

Detection Probabilities and Site Occupancy Estimates for Amphibians at Okefenokee National Wildlife Refuge

Abstract: We conducted an amphibian inventory at Okefenokee National Wildlife Refuge from August 2000 to June 2002 as part of the U.S. Department of the Interior's national Amphibian Research and Monitoring Initiative. Nineteen species of amphibians (15 anurans and 4 caudates) were documented within the Refuge, including one protected species, the Gopher Frog Rana capito. We also collected 1 y of monitoring data for amphibian populations and incorporated the results into the inventory. Detection probabilities and site occupancy estimates for four species, the Pinewoods Treefrog (Hyla femoralis), Pig Frog (Rana grylio), Southern Leopard Frog (R. sphenocephala) and Carpenter Frog (R. virgatipes) are presented here. Detection probabilities observed in this study indicate that spring and summer surveys offer the best opportunity to detect these species in the Refuge. Results of the inventory suggest that substantial changes may have occurred in the amphibian fauna within and adjacent to the swamp. However, mon...

Landscape Associations of Road-killed Virginia Opossums (Didelphis virginiana) in Central Massachusetts

Abstract: Knowing the distribution of species at the landscape level can give insight into the proximate mechanisms determining the species' range on a regional scale. We used a survey of road-killed animals to investigate landscape features associated with the presence of Virginia opossums (Didelphis virginiana) in central Massachusetts. Volunteers noted road-killed opossums on their daily commutes through the Connecticut River Valley and surrounding towns in 2000 and 2002. We used a GIS to characterize both the locations of roadkills and random points according to elevation, land use, distance to open water, traffic speed and number of observers on the road and then used logistic regression to determine the association of roadkill sites with these variables. Dead opossums were found most often at low-elevation sites with less forest cover and more human development. Although the opossum usually is considered a habitat generalist found primarily in association with woodlands, opossums in central Massachusetts are not associated with woodlands and, instead, are most often found in and near urbanized areas.

Description of spring roost trees used by female Indiana bats (myotis sodalis) in the Lake Champlain valley of vermont and New York

Abstract: Extensive effort has been directed at the roosting ecology of the federally endangered Indiana bat (Myotis sodalis) during the maternity season; however, spring roosting ecology has received much less attention. In April 2002, radio transmitters were attached to the back of 19 female Indiana bats as they emerged from a hibernaculum in northeastern New York. Thirty-nine roost trees were found in the vicinity of the Lake Champlain Valley of New York and Vermont over the span of 224 bat days (i.e., 1 bat located for 1 d equals 1 bat day). Distances from hibernaculum to roost trees ranged from 14.6 to 40.0 km (mean = 26.9 km). Shagbark hickory (Carya ovata) was the most common (33.3% of all trees, 39.7% of all bat days) of 11 tree species used. Roost trees had a mean diameter of 45.6 cm, were 18.9 m tall and were similar in structure to those used during summer by Indiana bats elsewhere in their range. This study provides the first large-scale examination of trees used by female Indiana bats after spring emergence, supplying critical life history information useful for the conservation of this species.

General Ecology of a Rural Population of Norway Rats (Rattus norvegicus) Based on Intensive Live Trapping

Abstract: We used intensive live trapping over a 1-y period to investigate the general ecology of a population of Norway rats (Rattus norvegicus) inhabiting a barn in east-central Illinois. At the start of our study in April 1986, the population contained 10 adult females and three adult males. The population increased and exhibited two peaks of about 100 individuals, one peak in late June and the other in late October 1986. Reproduction ceased during the late autumn and winter, and the population declined to only one adult male and one adult female by spring 1987. Increases in the number of rats represented young born at the barn, not adult rats moving into the population; decreases in population size likely resulted from predation rather than dispersal. Females first captured as adults persisted longer at the barn than did males and females first captured as juveniles or subadults; the few males first captured as adults persisted the shortest time of all age and sex classes. Young males gained body mass more rapidly than did young females. Wounding and parasitism by botflies occurred at relatively low levels. Our data indicate that a rat population with negligible immigration and seasonal breeding can exhibit dramatic changes in numbers, and that live-trapping at weekly intervals can yield high recapture rates useful for examining growth rates, survival and other basic life history characteristics.

Natural History of Mass-action in Predator-prey Models: A Case Study from Wolf Spiders and Grasshoppers

Abstract: Mass-action models of predator-prey interactions assume that predators encounter prey according to their relative densities as scaled by functional responses, although models seldom specify critical natural history and behavioral mechanisms that ensure that encounters actually occur. As a case study of this assumption, we assess the hypothesis that daily and seasonal activity and microhabitat use by wandering wolf spiders (Lycosidae: Schizocosa) searching for four common grasshopper species (Orthoptera: Acrididae) are coincident under natural conditions. There was great overlap in seasonal phenology and use of microhabitats between spiders and grasshoppers. Grasshoppers that were suitably sized (10–20 mm in length) as prey for spiders were relatively abundant from late spring through summer in this grassland. Three of the four common grasshopper species used microhabitat in a similar way, but differed from a fourth common species, Phoetaliotes nebrascensis. However, when they were active, spiders...

Effect of Plant Litter on Seed Predation in Three Prairie Types

Abstract: We used low-density seed additions to measure seed predation in eight 8-m × 8-m experimental plots at three prairie sites in 2002 and 20 experimental plots at each site in 2003. We added plant litter to one-half of the experimental plots (treatments), but not the other half (controls). Within each treatment and control plot, we established two seed plots, one available to all consumers and one available only to invertebrates. Seed removal by invertebrates did not differ between treatments and controls for any site or in either year. All consumers, collectively, removed significantly more seed from control plots in tallgrass prairie in both years but more seed from control plots in mixed-grass and shortgrass prairies only in 2003. These patterns suggested that rodents were the primary cause of differences in seed use between control and litter-augmented plots in the three prairie types; and plant litter in central North American grasslands negatively affects seed removal by rodents, but not ants.

Habitat Modeling Within a Regional Context: An Example Using Gopher Tortoise

Abstract: Changes in habitat are often a major influence on species distribution and even survival. Yet predicting habitat often requires detailed field data that are difficult to acquire, especially on private lands. Therefore, we have developed a model that builds on extensive data that are available from public lands and extends them to surrounding private lands. This model is applied for a five-county region in Georgia to predict habitats for the gopher tortoise (Gopherus polyphemus), based on analysis of documented locations of gopher tortoise burrows at the Fort Benning military installation in west central Georgia. Burrow associations with land cover, soil, topography and water observed within the military installation were analyzed with binary logistic regression. This analysis helped generate a probability map for the occurrence of gopher tortoise burrows in the five-county region surrounding Fort Benning. Ground visits were made to test the accuracy of the model in predicting gopher tortoise habitat. The results showed that information on land cover, soils, and distances to streams and roads can be used to predict gopher tortoise burrows. This approach can be used to better understand and effectively carry out gopher tortoise habitat restoration and preservation activities.

Food Habits of Louisiana Black Bears (Ursus americanus luteolus) in Two Subpopulations of the Tensas River Basin

Abstract: The Louisiana black bear (Ursus americanus luteolus) is listed federally as a threatened subspecies and current information about food habits is necessary for developing a sound conservation strategy. We collected and analyzed 251 scats from bears in the Tensas River Basin (TRB) population in northeast Louisiana. We compared diets of the two subpopulations (Tensas and Deltic) of the TRB and we observed differences during summer and fall. We suggest that the greater diversity of mast consumed by bears on Deltic may provide demographic stability to this small isolated subpopulation. Across the TRB, corn (Zea mays) made up the greatest percentage volume of scats and dominated summer and fall diet, whereas beetles (Coleoptera) were the food item found most frequently in scats. Other important food items included: blackberries and dewberries (Rubus spp.), acorns (Quercus spp.), palmetto fruit (Sabal minor), grasses/sedges (Poaceae or Cyperaceae), herbaceous vegetation and other species of soft mast.

Effects of mowing and summer burning on the Massasauga (Sistrurus catenatus)

Abstract: Prescribed fire is used to reduce coverage of woody vegetation in early successional habitats, but burning may also result in direct and indirect mortality of reptiles inhabiting the burn site. Mowing prior to burning has been hypothesized to render grassland habitats unsuitable for the massasauga (Sistrurus catenatus), thereby reducing the number of individuals that may be affected in the management unit at the time of burning. I evaluated the impact of mowing prior to summer burning on massasaugas at Squaw Creek National Wildlife Refuge, in northwestern Missouri, during the summer of 2003 using radiomarked snakes. Pre-burn mowing resulted in the direct mortality of three (43%) of seven radiomarked massasaugas present in the treatment area. Prescribed fire resulted in a mortality of one of two remaining individuals. Pre-burn mowing did not reduce mortalities as hypothesized and likely added to the overall snake mortality rate. Management alternatives other than mowing and prescribed fire when snakes are active should be considered when managing massasauga habitat.

Pollinator limitation, autogamy and minimal inbreeding depression in insect-pollinated plants on a boreal island

Abstract: We studied the pollination biology of 18 common insect-pollinated plant species on Kent Island, a boreal island in the Bay of Fundy, New Brunswick, Canada. Under natural conditions, fruit set was relatively high in most of the species studied [although it was very low (<1%) in Maianthemum canadense]. Hand-pollination increased fruit set in five of seven species examined (71%), indicating that fruit set may commonly be limited by the availability or behavior of pollinators on Kent Island. Twelve of 17 species examined (71%) were capable of substantial autonomous self-pollination (autogamy in the absence of pollinators), although fruit set averaged higher in open-pollinated flowers (65.7%) than in flowers from which insects were experimentally excluded (49.6%). The number of seeds per fruit was also less in autonomously self-pollinated flowers in two species (Rhododendron canadense and Ledum groenlandicum). In at least one species (Iris versicolor), rates of autonomous selfing were higher on Kent Island than on the mainland. Stamen-excision experiments in I. versicolor demonstrated that fruit set required pollen transfer in the absence of pollinators (i.e., agamospermy did not occur). In hand-pollination experiments, five of six species (83%) (R. canadense, L. groenlandicum, Smilacina trifolia, S. stellata and I. versicolor) showed no evidence of inbreeding depression in terms of percent fruit set, fruit size or number of seeds per fruit. Overall, our results demonstrate that for many insect-pollinated plant species on Kent Island, pollinators are likely to be limiting, autogamy is common and inbreeding depression is negligible. Although pollinator limitation and autogamy regularly occur in mainland habitats as well, a review of the literature suggests that they may be more common on islands such as Kent Island. If such island-mainland differences are general, they may arise because genotypes and species capable of self-fertilization are more likely than obligate outcrossers to colonize and become established in isolated habitats.

Influence of an Invasive Crayfish Species on Diurnal Habitat Use and Selection by a Native Crayfish Species in an Ozark Stream

Abstract: The crayfish Orconectes neglectus chaenodactylus has recently been introduced into the Spring River drainage in southern Missouri and northern Arkansas and appears to be displacing the native species O. eupunctus. To determine if O. eupunctus and O. neglectus chaenodactylus compete for habitat, we examined if either species shift habitats when in the presence of one another. Habitat use of juvenile and adult crayfish was determined in six habitat types (backwater, pool, riffle, run, stream margin and vegetation) with a quadrat sampler during July/August 2003 at three sites: (1) an upstream site where O. neglectus chaenodactylus occurs, (2) a zone of overlap where both species occur and (3) a downstream site where O. eupunctus occurs. Habitat selection was determined by comparing habitat use to habitat availability. Redundancy Analyses were used to determine the relationship between crayfish densities and measured environmental variables (current velocity, water depth and percent boulder, cobble, ...

Use of Stable Isotopes to Test Literature-based Trophic Classifications of Small-bodied Stream Fishes

Abstract: Defining the trophic position of stream organisms is a first step in understanding the ecology of lotic systems. Whereas trophic positions of stream fishes have been traditionally assigned based on dietary analysis, stable isotope ratios may provide additional information on the validity of this approach and may be used to verify energy acquisition assumed from dietary studies. In this study, we assessed the concordance of literature-based trophic classifications and isotopic δ15N signatures for small-bodied fishes from four streams in Kansas, Oklahoma and New Mexico. ANOVA results revealed no significant difference (F2,27 = 1.71, P = 0.201) in trophic position based on δ15N values among three broad trophic classifications derived from literature sources (algivores/detritivores, omnivores and invertivores). Both the prevalence of omnivory in stream fishes and potential biases associated with isotope fractionation at different trophic levels poses potential problems when classifying lotic fish int...

Response of Rocky Mountain Elk (Cervus elaphus) to Wind-power Development

Abstract: Wind-power development is occurring throughout North America, but its effects on mammals are largely unexplored. Our objective was to determine response (i.e., home-range, diet quality) of Rocky Mountain elk (Cervus elaphus) to wind-power development in southwestern Oklahoma. Ten elk were radiocollared in an area of wind-power development on 31 March 2003 and were relocated bi-weekly through March 2005. Wind-power construction was initiated on 1 June 2003 and was completed by December 2003 with 45 active turbines. The largest composite home range sizes (>80 km2) occurred April–June and September, regardless of the status of wind-power facility development. The smallest home range sizes (<50 km2) typically occurred in October–February when elk aggregated to forage on winter wheat. No elk left the study site during the study and elk freely crossed the gravel roads used to access the wind-power facility. Carbon and nitrogen isotopes and percent nitrogen in feces suggested that wind-power development...

Population Status and Habitat Selection of the Endangered Key Largo Woodrat

Abstract: Over the last two decades, declines in trap success, stick-nest density and population density estimates have fueled concerns that the federally endangered Key Largo woodrat (KLWR, Neotoma floridana smalli) population is declining. Information on the current population status and habitat selection of KLWR is needed in the recovery of this population. We trapped on 60 (1-ha) randomly-placed grids (20 grids in each of three hardwood hammock age-classes). Grids were trapped from March–September 2002 and April–August 2004. Population estimates for the two trapping periods were 106 (95% ci 30–182) and 40 (95% ci 5–104) individuals, respectively. Greater than 80% of all KLWRs captures occurred in the young hammock age-classes (disturbed after 1971). Young hammocks were characterized by a more open canopy, smaller overstory trees, fewer logs, greater dispersion of overstory trees and a different species composition than old and medium age hammocks (P < 0.024). Contrary to previous research, KLWRs were f...

Growth, Body Condition, Reproduction and Survival of Stocked Barrens Topminnows, Fundulus julisia (Fundulidae)

Abstract: We documented the fate of 29 cohorts of propagated Barrens topminnows Fundulus julisia stocked as juveniles and adults (ntotal = 2770 fish) into 17 springheads and small ponds in middle Tennessee in 2003 and 2004. Annual mortality rates were calculated after estimating the number of individuals of each cohort remaining 1–18 mos after fish were stocked. Lighted larval fish traps were deployed at seven reintroduction sites and the Type Locale to determine whether topminnows could reproduce in the presence of the introduced-transplanted Western mosquitofish Gambusia affinis. At stocking sites harboring mosquitofish (n = 12), their density ranged from 0.4 to 66.3 mosquitofish per m2. Annual mortality of stocked Barrens topminnows ranged from 45 to 100% and 24 cohorts experienced annual mortality greater than 95%. Mortality was not related to mosquitofish density or the mean size at stocking. The robustness of Barrens topminnows did not differ in the presence or absence of mosquitofish, suggesting tha...

Consumption of caterpillars by bats during an outbreak of western spruce budworm

Abstract: We investigated the diets of insectivorous bats (Chiroptera: Vespertilionidae) in forests with high densities of western spruce budworm (Choristoneura occidentalis, Lepidoptera: Tortricidae), in southern interior British Columbia, Canada. Caterpillars as potential prey were more common and widespread than previously reported. Caterpillar consumption by bats was more frequent where C. occidentalis larvae were more abundant, suggesting that the caterpillars being eaten were C. occidentalis. The frequency of caterpillar consumption was similar for Myotis evotis, which gleans prey from vegetation, and for other bat species that forage primarily by aerial-hawking. We suggest that caterpillars hanging by silk threads were captured by bats that foraged aerially.