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We examined vegetation and invertebrate characteristics, including insect biomass, insect-prey, six Families and seven Orders in four varieties of Conservation Reserve Program (CP10, improved CP10, CP2 and CP25) and wheat fields in western Kansas during Jun. and Jul., 2004 and 2005 relative to gamebird chick ecology. CP10 fields had less bare ground and forbs compared to the other Conservation Practices and CP25 fields had lost much of their original forb component by the end of the study. Although there was little forb component, CP10 fields had high invertebrate biomass. However, CP10 fields demonstrated sizeable declines in the estimated effect size of examined invertebrate characteristics between sampling periods unlike the other mixes. Unharvested wheat (Triticum aestivum), CP10 and improved CP10 fields had the greatest number of insect-prey. Overall, most fields had adequate insect-prey availability suggesting that in terms of insect availability for gamebird chicks, these fields provide excellent brood feeding opportunities, therefore accessibility and other issues might be more important in determining habitat “quality” for gamebird chicks.
We compared the beetle fauna captured in 12 pairs of flight intercept traps suspended at two different heights above the ground (≥15 m and 0.5 m) in a temperate deciduous forest in the southeastern United States to better understand how the abundance, species richness, diversity and composition of insect communities differ among forest strata. A total of 15,012 beetle specimens were collected representing 73 families and 558 morphospecies. Shannon's diversity and evenness were both higher near the ground than in the canopy, but no differences in total abundance or species richness between the two layers were observed. There were many differences at the family level, however, and species composition differed considerably between the two layers. About 29% and 31% of species were captured exclusively in the canopy or near the ground, respectively. The canopy traps were more similar to one another than they were to those near the ground and vice-versa based on both Sorensen's quotient of similarity and Raabe's percentage of similarity. The canopy and ground trap locations were quite distinct based on nonmetric multidimensional scaling. The degree to which species composition was similar (i.e., Sorensen's quotient of similarity) between pairs of traps decreased significantly with inter-trap distance for the traps in the canopy, but not for those near the ground, suggesting a more uniform community near the ground. Of the 41 families or subfamilies represented by more than 40 individuals, 12 were more abundant in the canopy and 14 were more abundant near the ground. Similarly, of the 16 families or subfamilies represented by more than 10 species, five were more species rich in the canopy and four were more species rich near the ground. Three families (Cerambycidae, Cleridae and Coccinellidae) were both more abundant and species rich in the canopy, whereas four other groups (Carabidae, Pselaphinae (Staphylinidae), Scolytinae (Curculionidae) and other Staphylinidae) were both more abundant and species rich near the ground. In addition to differing considerably among families, the vertical distribution patterns varied within many families as well. The distribution patterns for several groups are discussed in some detail with respect to known life history information.
Agalinis auriculata (Orobanchaceae) is a state-listed species in Illinois and is rare throughout its range in the midwestern United States. In recent years, research has been conducted on the biology of this hemiparasitic plant in order to understand better what factors should be included in the development of sound preservation practices. Our objective in this study was to assess genetic variation using allozyme and RAPD markers for Illinois populations of A. auriculata and two of its more common congeners, A. purpurea and A. tenuifolia. A total of 13 allozyme loci and 112 RAPD markers were scored for the studied species. Overall, lower percent polymorphic loci/markers were observed in A. auriculata than in its congeners. Analyses of molecular variance on RAPD markers showed that most of the genetic variation was within populations. In addition, the allozyme and RAPD UPGMA and RAPD principle coordinates analyses separated the three species of Agalinis. The genetic results of this study in conjunction with ecological studies of A. auriculata in Illinois serve as a springboard for the conservation of the species, not only in Illinois but also throughout its range.
The evaluation of appropriate sampling methodologies is critical for accurately determining the distribution and status of herpetofaunal populations. We report the results of a year-long drift fence study, using multiple trap types (large pitfall traps, small pitfall traps and funnel traps), of a species-rich herpetofaunal community (59 species) surrounding an isolated wetland in the southeastern United States. Specifically, we determined the effects that timing, trap type and taxon had on capture rates of herpetofauna. We found that funnel traps captured the greatest number of herpetofaunal species, but a combination of funnel traps and large pitfall traps yielded the greatest number of individual captures due to complementary biases in capture efficiencies among herpetofaunal taxa. With little exception, small pitfall traps were relatively ineffective for sampling herpetofauna. We also found that the timing of drift fence monitoring affected herpetofaunal species accumulation rates but that seasonal effects were taxon-specific. Our study affirms that drift fences are exceptional tools for inventorying and monitoring diverse species and large numbers of herpetofauna and also demonstrates the important effects that season and taxon can have on capture rates. Therefore, we recommend a priori delineation of project goals and the use of multiple trap types with careful attention to the timing of drift fence monitoring to maximize sampling efficiency and minimize biases associated with data collection.
We investigated the life history and demographics of Notropis rafinesquei (Cyprinidae) in three streams in north Mississippi, USA, over 2 y. Size at maturity (22.5–29.3 mm SL) and the timing and duration of the reproductive period (Apr.–Aug.) were similar among all three streams in both years. We consistently detected two young-of-the-year cohorts, one strong cohort appearing in early summer and the other of varying strength in fall. In contrast, we found striking variation in most other life history traits including female length, body weight, clutch size, ova diameter and sex ratios, despite the close geographic proximity of these populations. Life history traits of all other species in the Notropis longirostris clade (N. ammophilus, N. longirostris and N. sabinae) are similar to N. rafinesquei, but like N. rafinesquei, vary widely among and within species. The highly plastic nature of reproductive traits in N. rafinesquei and other members of the N. longirostris clade is likely an important adaptation that allows these animals to maintain large populations in the often physically unstable and unpredictable stream environments of the Gulf Coastal Plain, USA.
Nonindigenous earthworms are causing large and undesirable changes to forests across the U.S. Upper Midwest. Because earthworms have slow rates of natural spread, and because their distribution remains patchy in many areas, it would be possible to slow the rate of invasion if vectors of introduction can be identified and controlled. Earthworm populations are often found near lakes, and it has been suggested that anglers discarding unwanted bait are a vector for the establishment of new populations. Here, we have surveyed the bait trade and anglers to determine whether bait stores sell known invasive species and whether angler behavior is likely to lead to these species becoming introduced near lakes. All bait stores surveyed sold known invasive species and 44% of anglers who purchase bait dispose of unwanted bait on land or in trash. We conclude that the bait trade and subsequent disposal of worms by anglers constitute a major vector for earthworm introductions. Thus, slowing the spread of invasive earthworms will require efforts to change the species sold at bait stores and/or efforts to change angler behavior.
As invaders to North America, zebra mussels (Dreissena polymorpha) have contributed to the decline of benthic species, the mechanisms of which are poorly understood. In this study, we examined effects of D. polymorpha biofouling on locomotion of one pleurocerid snail (Elimia livescens) and two unionid bivalves (Ligumia nasuta and Anodonta grandis) using observational studies and removal experiments. In field and laboratory experiments, E. livescens without zebra mussels traveled 1.5–1.6 times farther than snails with zebra mussels. In field experiments, unionids without zebra mussels traveled farther and were more likely to move than unionids colonized by zebra mussels. Decreases in travel distance in the snail, but not unionids, were significantly correlated with zebra mussel loading relative to host animal mass. Limited mobility caused by zebra mussels may have consequences for gastropods and unionids by disrupting reproductive habits, predator evasion and avoidance of unbearable environmental conditions. Localized extinctions may occur due to inability to disperse or energetic costs associated with carrying zebra mussels. Mobility constraints resulting from zebra mussel biofouling may be an important mechanism of population declines in native mollusk species.
Conservation plans for the Preble's meadow jumping mouse (Zapus hudsonius preblei), a threatened subspecies, commonly include habitat restoration. Our objective was to determine if Z. h. preblei would detect and use supplemental food and cover (simulated restoration) placed in areas where the mouse had not been documented for 3 y, thus altering their movement and site fidelity behaviors. Through monitoring of radiotagged mice during pre- and post-treatment periods, we documented the mouse's immediate, short-term movement response to the addition of supplemental resources. Results were mixed with only 1 of 11 individuals using a single treatment plot in 2002 compared to 6 of 8 individuals using 50% of the treatment plots in 2003, including 1 individual radiotagged in both years. Zapus h. preblei use of supplemental resources may have been limited by and affected temporally by a combination of factors including: (1) site fidelity and (2) precipitation (2002 was much drier) and its potential impacts on habitat, exploratory movements to detect new habitat and elevated predation risk. These results suggest that detection of restored habitat by Z. h. preblei, at least in the short-term, may not be certain and underscore the need for direct monitoring after restoration efforts to ensure that use occurs and desired effects such as long-term persistence are attained.
Published information about the diet of eastern small-footed bats (Myotis leibii) does not exist. Feces of 39 M. leibii captured from May through Sep. in southern New Hampshire contained eight orders of insects, spiders (Araneae), unidentified arthropods and vegetation. Moths (Lepidoptera), true flies (Diptera) and beetles (Coleoptera) composed most of the diet. Diet of adult males contained significantly fewer beetles than that of juveniles, but diet was similar between other demographic groups and across seasons. Presence of spiders and crickets (Gryllidae) in the diet suggested M. leibii captured some prey via gleaning.
We used radiotelemetry to locate 51 diurnal roosts for 17 male Seminole bats (Lasiurus seminolus) during late spring and early summer, 2000–2005. We quantified characteristics of roost trees and sites surrounding roosts and compared those measurements with random trees and random locations. All but two roosts were located in the foliage of large overstory pines (Pinus sp.). All roosts were in trees ≥21.7 cm dbh and roost trees were taller and greater in diameter than random trees. A conditional logistic regression model differentiating roost sites from random locations indicated Seminole bats were more likely to roost at sites with more pines 25.0–49.9 cm dbh, fewer pines 10.0–24.9 cm dbh, lower overstory hardwood basal areas (BA) and more recently cut stumps than random; bats selected open forest sites dominated by large (>20.0 cm dbh) pines. Eighty-four percent of roosts were located in stands that were recently partially harvested or thinned but retained large overstory pines. Relatively open pine forest, with abundant large overstory pines, is important roosting habitat for male Seminole bats during summer on the western edge of their range.
The restoration or conservation of predators could reduce seroprevalences of certain diseases in prey if predation selectively removes animals exhibiting clinical signs. We assessed disease seroprevalences and blood parameters of 115 adult female elk (Cervus elaphus) wintering on the northern range of Yellowstone National Park [YNP] during 2000–2005 and compared them to data collected prior to wolf (Canis lupus) restoration (WR) in 1995 and to two other herds in Montana to assess this prediction. Blood parameters were generally within two standard deviations of the means observed in other Montana herds (Gravelly-Snowcrest [GS] and Garnet Mountain [GM]), but Yellowstone elk had higher seroprevalences of parainfluenza-3 virus (95% CI YNP = 61.1–78.6, GS = 30.3–46.5) and bovine-virus-diarrhea virus type 1 (95% CI YNP = 15.9–31.9, GM = 0). In comparisons between pre-wolf restoration [pre-WR] (i.e., prior to 1995) seroprevalences with those post-wolf restoration [post-WR] in Yellowstone, we found lower seroprevalences for some disease-causing agents post-wolf restoration (e.g., bovine-virus-diarrhea virus type-1 [95% CI pre-WR = 73.1–86.3, post-WR = 15.9–31.9] and bovine-respiratory syncytial virus [95% CI pre-WR = 70.0–83.8, post-WR = 0]), but similar (e.g., Brucella abortus [95% CI pre-WR = 0–4.45, post-WR = 0–4.74] and epizootic hemorrhagic disease virus [95% CI pre-WR = 0, post-WR = 0]) or higher for others (e.g., Anaplasma marginale [95% CI pre-WR = 0, post-WR = 18.5–38.7] and Leptospira spp. [95% CI pre-WR = 0.5–6.5, post-WR = 9.5–23.5]). Though we did not detect an overall strong predation effect through reduced disease seroprevalence using retrospective comparisons with sparse data, our reference values will facilitate future assessments of this issue.
We estimated home-range size for American marten (Martes americana) in northern Wisconsin during the winter months of 2001–2004, and compared the proportion of cover-type selection categories (highly used, neutral and avoided) among home-ranges (95% fixed-kernel), core areas (50% fixed-kernel) and the study area. Average winter home-range size was 3.29 km2 with home-ranges of males (n = 8, mean = 4.25 km2) significantly larger than females (n = 5, mean = 2.32 km2). Composition of cover-type selection categories in home-ranges differed significantly from what was available in the study area (X2 = 6.9145, df = 2, P > 0.0315) with more highly used habitat and less avoided habitat than expected. Consistent with research in other regions, 72% of an American marten home-range contained highly used cover-types and 18% of a home-range contained avoided types with the remainder of the average home-range composed of neutral cover-types. This suggests that Wisconsin American martens select habitat at the home-range scale based on the occurrence of highly used and avoided cover types. Proportions of selection categories in core areas did not differ significantly from what was available in the study area or in home-ranges. Core areas were significantly smaller than home-ranges and this observation combined with the lack of cover-type selection at the core area scale suggests that American martens select core areas based upon micro-site features (e.g., rest sites) rather than broad-scale cover types. The findings presented here may assist wildlife managers in management activities by identifying potentially suitable habitat.
We investigated causes of body mass loss associated with consecutive days of live trapping of old-field mice (Peromyscus polionotus) on four small mammal trapping grids in central Florida USA from Mar. 2003 to Dec. 2004. Body mass of P. polionotus declined when live trapped for two consecutive days. Mean mass losses were recorded in all seasons and were significantly different in spring and summer. Temperatures inside live traps were higher than ambient temperatures. Mean number of sunflower seeds ingested was not different between day one and day two of capture, and the total number of sunflower seeds consumed explained a small amount of the variation in body mass loss. Our results suggest that sunflower seeds are not a good source of water necessary to maintain a constant body mass in P. polionotus live trapped on consecutive days, and mass loss is influenced by a combination of seasonal temperature fluctuations and physiological condition of trapped individuals.
Habitat use, feeding and activity patterns of Big Cypress fox squirrels (Sciurus niger avicennia) were studied in southwest Florida to identify golf course features favorable to fox squirrels. The location, behavior and foods of 30 radio-located squirrels were recorded twice weekly from Dec. 1995 to Jul. 1997. Diet was >85% food from native conifers for 6 mo (Aug.–Jan.), >75% flowers and fruits of planted exotics for 3 mo (Feb.–Apr.) and a variety of foods supplemented by mushrooms and webworm larvae for 3 mo (May–Jul.). Ground feeding accounted for 69.6% of observations. Use of foods from exotic species was associated with greatest reproduction in the summer. Five categories of behavior in adults (feeding, travel, resting, nesting, social interactions) showed significant interaction between sex and time-of-day and season and time-of-day in a log-linear model. Squirrels were least active during the hottest part of the year. Squirrels concentrated their activity in tree stands of the course's roughs. Squirrels were more likely to use open areas to travel between tree stands than for other activities. Among patches of trees, stands dominated by Pinus elliottii and Taxodium sp. and by P. elliottii and Sabal palmetto were used the most. Squirrels used pure stands of S. palmetto and stands of mixed natives less than expected based on availability. Dense understory reduced overall stand use and ground foraging. Golf course design and management directly affect features favorable to Big Cypress fox squirrels and may determine the value of golf courses in conservation.
A metapopulation is any set of populations that are patchily distributed and potentially connected by dispersal. This broad definition includes classical, mainland-island, source-sink, patchy and non-equilibrium metapopulations. To ensure long-term regional population viability in a fragmented landscape we need a better understanding of metapopulation dynamics. To determine which metapopulation model applies to a given species, Stith et al. (1996) developed a classification scheme using species-specific estimates of dispersal distance and local extinction risk. We used this scheme to classify bobolink (Dolichonyx oryzivorus) populations occupying fragmented, agricultural grasslands in the Midwestern United States. We estimated the distribution of dispersal distances using mark-recapture techniques and calculated local extinction risk. Dispersal rate and turnover were high, indicating that populations were highly connected. Local extinction probability was 4%, indicating that populations were “midlands” and vulnerable to extinction. Well-connected populations constitute a patchy metapopulation according to Stith et al.'s (1996) scheme. Bobolink dispersal ability was sufficient to overcome habitat fragmentation. Our research showed that the Stith et al. (1996) classification can be applied to a migratory species, but should be expanded to the metalandscape scale.
We examined the relationship between pitcher characteristics (sugar concentration in nectar, percentage of red coloration and three indices of size) and prey capture in three populations of the carnivorous plant, Sarracenia alata Wood. The indices of size (height, funnel diameter and hood area) were highly correlated in all three populations. Pitcher size and mass of prey capture per day differed significantly among populations. Pitcher size was significantly positively related to total mass of prey capture per day, explaining 37–76% of the variation depending on the population. The sugar concentration in nectar and the red coloration as we measured them were not important in determining prey capture. Examining alternative measurements of nectar (e.g., total nectar production and/or presence of amino acids), volatiles and the presence of UV reflectance patterns may yield further insight into the relationship between pitcher characteristics and prey capture.
In recent decades, substantial areas of North American tallgrass prairie have been lost to the establishment and expansion of woodlands and forests, including those dominated by eastern redcedar (Juniperus virginiana). This shift in dominant plant life form, from C4 grasses to coniferous trees, may be accompanied by changes in productivity, standing stocks of biomass and nutrients and biogeochemical cycles. The goal of this study was to quantify and compare major pools and fluxes of nitrogen in recently established (≤ 80 y) redcedar forests and adjacent native grasslands. Three former grassland sites in the Flint Hills region of Kansas that developed closed-canopy redcedar forests in the recent past were paired with adjacent grassland sites on similar soil type and topographic position (n = 3 sites/land cover type), and selected soil and plant nitrogen pools and fluxes were measured in replicate plots (n = 6/site) along transects in each forest or grassland site over a 20-mo period. We found few significant differences in median soil inorganic N pools or net N mineralization rates between the forest and grassland sites, though there was a trend for greater concentrations of inorganic N in grassland sites on most sample dates, and cumulative growing season net N mineralization averaged 15% less in forest sites (14.3 kg N·ha−1·yr−1) than in grassland sites (16.9 kg N·ha−1·yr−1). Mean aboveground plant productivity of forest sites (9162 kg ha−1 yr−1) was about 2.5× greater than that of comparable grasslands (similar soils and topographic position), in spite of similar levels of soil N availability. This resulted in an ecosystem-level nitrogen use efficiency (ANPP∶litterfall N) in forests that was more than double that of the grasslands they replaced. Additional changes in N cycling associated with redcedar forest development included large accumulations of N in aboveground biomass and transfer to the forest floor via litterfall; redcedar aboveground biomass contained 617 kg N/ha, forest floor litter N was 253 kg N/ha, and litterfall N flux was 41 kg ha−1·yr−1. These are substantial increases in aboveground biomass N accumulation, surface litter N inputs, and surface litter N accumulation compared to the native grasslands characteristic of this region. These fundamental shifts in ecosystem patterns and processes have the potential to alter regional biogeochemistry and both nitrogen and carbon storage throughout areas of the eastern Central Plains where coverage of redcedars is increasing.
The goal of this research was to develop a novel method to make use of ranked timber observation descriptions, which have been underutilized in survey reconstruction research. The new method involves assuming that ranking position reflects relative importance and thereby produces four separate measures that can be used to describe the geographic distribution, relative abundance and dominance of taxa recorded in historical surveys. We believe the method allows researchers to describe the composition of the forest from the line description data in a manner that would be impossible working only with witness tree data. The method is demonstrated using the Twenty Townships survey (central New York) as a case study, an area not previously discussed in the literature. We found that beech (Fagus grandifolia), maple (Acer spp.), basswood (Tilia americana) and hemlock (Tsuga canadensis) were the most widely distributed taxa and that these four taxa were more or less abundant in this same order. Where they were present, beech and hemlock were dominant, while maple and basswood were less so. Ash (Fraxinus spp.), birch (Betula spp.), elm (Ulmus spp.), cherry (Prunus spp.), pine (Pinus spp.) and cedar (Thuja spp.) were minor elements of the forest composition, but ash and cedar were both the primary constituents of swamps in the region, making them dominant taxa when they were present. Chestnut (Castanea dentata), oak (Quercus spp.), alder (Alnus spp.), ironwood (Ostrya virginiana), butternut (Juglans spp.) and walnut (modern day Carya spp.) were also present, but they were extremely rare.
Effects of 74 episodes of extreme weather on stoppage of population growth and resulting amplitudes of annual population fluctuation of 39 fluctuations of Microtus ochrogaster and 20 fluctuations of M. pennsylvanicus were studied over a 25 y period in east-central Illinois. Episodes of extreme weather may have stopped population growth of only six M. ochrogaster fluctuations and of two M. pennsylvanicus fluctuations. Cessation of growth of only one population fluctuation (M. pennsylvanicus) could be attributable solely to an episode of extreme weather. Episodes of extreme weather occurred during 62% of the increase phases of M. ochrogaster population fluctuations and 75% of those of M. pennsylvanicus, with no associated cessation of population growth. We conclude that episodes of extreme weather were not a primary factor responsible for cessation of population growth or variation in amplitudes of population fluctuations of either M. ochrogaster or M. pennsylvanicus.
After analyzing DNA obtained from fecal samples gathered in Michigan, Swanson and Rusz (2006) claimed that 83% of identified scats were from cougars, indicating to them that a population of these large carnivores existed in the state. In this paper, we identify problems with their methodology, suggest that they unreasonably extrapolated their conclusions and point out that their results are improbable, especially in light of no other evidence in the scientific literature suggesting the existence of a population of cougars in Michigan.
Disturbance often promotes plant invasion. Small disturbances to the forest floor expose bare soil to light which may promote seed germination and establishment. We tested the hypothesis that small disturbances to the litter layer allow invasive species to become established in forest interiors. We found that seedlings of the invasive shrub Lonicera maackii were found in sites with significantly lower leaf litter mass than regularly spaced points along a transect. We then investigated establishment and survival of L. maackii and the invasive biennial Alliaria petiolata in plots randomly assigned to three treatments: litter removed, litter added and control. Significantly more L. maackii seedlings established in the litter removed and control plots than the litter added treatments, but there was no effect on survival. Significantly more A. petiolata seedlings established in the litter removed plots than in the control or litter added treatments. Survival of established A. petiolata seedlings was significantly greater in control than in litter removed plots, but the final number of A. petiolata seedlings was greatest in the litter removed treatment. Our results confirm that bare patches of soil in the forest interior are colonization sites for invasive plant species.