Showing papers in "American Midland Naturalist in 2000"
TL;DR: This review of papers that compared intraspecific variation in territoriality vs. alternative forms of spatial or behavioral organization found several reasons why food resources are cited most often, including their biological significance, ease of study and publishability of negative results.
Abstract: We reviewed papers that compared intraspecific variation in territoriality vs. alternative forms of spatial or behavioral organization with three goals: (1) to discover which ecological variables act as determinants of territorial behavior and how they might act; (2) to extract and evaluate predictions and evidence for determinants of territoriality and (3) to suggest ways for future studies to build upon what the review revealed. Twenty ecological variables have been predicted, correlated with or experimentally demonstrated to relate to territoriality within vertebrate species. These variables include several characteristics of food: quantity, predictability, distribution, quality, renewal rate, type, density and assessibility. Other variables include nonfood resources, population density, habitat features, mates, space, refuges/spawning/home sites, predation pressure, host nests (for brood parasites) and energy availability. We suggest several reasons why food resources are cited most often, in...
305 citations
TL;DR: Results demonstrate direct effects of the invasive shrub Lonicera maackii on populations of annuals and suggest that other annuals, particularly those that are shade-intolerant or photosynthesize only in the early spring, will decline in the presence of shrubs with early leaf expansion.
Abstract: Negative effects on native plant populations are often attributed to invasions by exotic plants, but experimental evidence is lacking to support many of these claims. Lonicera maackii, an exotic shrub with long leaf phenology, has become naturalized throughout the eastern United States. This study investigated the effects of L. maackii on demography of Galium aparine, Impatiens pallida and Pilea pumila, native annual herbs in differing phenological categories. These interactions were examined in two Ohio forest stands. One stand has a history of logging, burning and grazing and a higher L. maackii density, whereas the other stand has little anthropogenic disturbance and a lower L. maackii density. Three types of experimental plots were established: L. maackii removal, L. maackii present and, at the less disturbed stand, L. maackii absent. Seedlings of the annuals were transplanted and monitored for 1 y for survival to reproductive age and fecundity. In the more disturbed stand, survival of Galium...
235 citations
TL;DR: Results show that alien annual grasses can compete with native annual plants and an alien forb in the Mojave Desert and that effects can vary among years.
Abstract: Alien annual grasses in the genera Bromus and Schismus are widespread and abundant in the Mojave Desert, and negative correlations between these aliens and native annual plants suggest that competition may occur between them. Effects of competition were evaluated by thinning alien annual grass seedlings and measuring the responses of native annual plants at three sites in the central, southcentral and southwestern Mojave Desert during 2 y of contrasting plant productivity. Effects of Bromus and Schismus were evaluated separately in the microhabitat where each was most abundant, beneath the north side of creosote bushes (Larrea tridentata) for Bromus and in the open interspace between shrubs for Schismus. Thinning of Bromus and Schismus significantly increased density and biomass of native annuals at all three sites, only during a year of high annual plant productivity and species richness. Effects of thinning were greatest for Amsinckia tesselata and for a group of relatively uncommon native annuals. Thinning also significantly increased the density and biomass of the alien forb, Erodium cicutarium. These results show that alien annual grasses can compete with native annual plants and an alien forb in the Mojave Desert and that effects can vary among years.
157 citations
TL;DR: It is shown that the response of specific leaf area to nitrogen fertilization can be highly plastic and substantially increases the aboveground competition for light along nitrogen gradients.
Abstract: Specific leaf area was measured for three dominant perennial grass species in a long term nitrogen fertilization experiment in an abandoned field in Minnesota. The specific leaf area differed among the species and increased with increasing levels of nitrogen fertilization. This increase in specific leaf area was up to 82% for Agropyron repens and shows that the response of specific leaf area to nitrogen fertilization can be highly plastic. Increasing specific leaf area within species, together with a species replacement, resulted in a 202% increase in leaf area index along the nitrogen gradient, whereas the biomass increased by only 57%. One-third of this increase was attributed to species replacement and two-thirds to the change in specific leaf area within species. This plastic response of specific leaf area within plant species substantially increases the aboveground competition for light along nitrogen gradients.
142 citations
TL;DR: In this paper, the Buffalo Ridge windplant site was investigated for dead birds and the search efficiency, predator scavenging rates and rate of carcass decomposition were evaluated. But the results showed that birds killed at existing windplants in California caused concern about the potential impacts of wind power on the avian community.
Abstract: Recent technological advances have made wind power a viable source of alternative energy production and the number of windplant facilities has increased in the United States. Construction was completed on a 73 turbine, 25 megawatt windplant on Buffalo Ridge near Lake Benton, Minnesota in Spring 1994. The number of birds killed at existing windplants in California caused concern about the potential impacts of the Buffalo Ridge facility on the avian community. From April 1994 through Dec. 1995 we searched the Buffalo Ridge windplant site for dead birds. Additionally, we evaluated search efficiency, predator scavenging rates and rate of carcass decomposition. During 20 mo of monitoring we found 12 dead birds. Collisions with wind turbines were suspected for 8 of the 12 birds. During observer efficiency trials searchers found 78.8% of carcasses. Scavengers removed 39.5% of carcasses during scavenging trials. All carcasses remained recognizable during 7 d decomposition trials. After correction for bia...
123 citations
TL;DR: In this paper, the authors measured bird occurrence and corresponding vegetation attributes on mixed-grass prairie in northwestern North Dakota during 1993-1994 and found that ten grassland passerine species occurred commonly (i.e., at >10% of point count locations), including two species endemic to the northern Great Plains [Baird's sparrow (Ammodramus bairdii) and Sprague's pipit (Anthus spragueii)], and several species of management concern [bobolink (Dolichonyx oryzivorus), grassho
Abstract: With grassland bird populations in the Great Plains exhibiting steep declines, grassland managers require information on bird habitat needs to optimally manage lands dedicated to wildlife. During 1993–1994, we measured bird occurrence and corresponding vegetation attributes on mixed-grass prairie in northwestern North Dakota. Three hundred and ten point-count locations over a wide range of successional stages were sampled. Ten grassland passerine species occurred commonly (i.e., at >10% of point count locations), including two species endemic to the northern Great Plains [Baird's sparrow (Ammodramus bairdii) and Sprague's pipit (Anthus spragueii)], and several species of management concern [bobolink (Dolichonyx oryzivorus), grasshopper sparrow (Ammodramus savannarum), clay-colored sparrow (Spizella pallida)]. Some species were ubiquitous and had generalized habitat associations [e.g., savannah sparrow (Passerculus sandwichensis)]. Others exhibited more finely tuned, closely overlapping use of rel...
108 citations
TL;DR: In this paper, the relationship of herbaceous plant diversity to overstory composition and stand structure in mixed aspen forest of northern Minnesota was investigated on 23 study sites that contained aspen in monoculture or in mixture with boreal conifers or northern hardwood species.
Abstract: The relationship of herbaceous plant diversity to overstory composition and stand structure in the mixed aspen forest of northern Minnesota was investigated on 23 study sites that contained aspen in monoculture or in mixture with boreal conifers or northern hardwood species. On each site overstory species were placed into species groups: conifers, aspen and hardwoods other than aspen. Each site was then placed in one of three cover-type groups based on proportion of the overstory species groups: Aspen (>0.9 basal area in aspen), Aspen-Conifer (>0.15 basal area in conifer species) and Aspen-Hardwood (>0.15 basal area in hardwood species other than aspen). The relationships between diversity of herbaceous vegetation and the following factors were tested: (1) overstory composition, defined as the proportion of basal area by species group in the overstory and (2) stand structure. Stand structure was described by the vertical position and horizontal arrangement of balsam fir within the stand. In addit...
102 citations
TL;DR: Better understanding of all aspects of the life cycle, transmission, host-parasite relationships and the effective control of C. formosanus in Mexico is necessary and adequate preventive and control measures should be applied in aquaculture.
Abstract: The taxonomy, distributional history, present occurrence, life cycle, morphology of developmental stages and epizootiology of the heterophyid trematode Centrocestus formosanus (Nishigori, 1924) in Mexico are reviewed. This parasite was most likely introduced to Mexico with the importation of the first intermediate host, the thiarid snail Melanoides tuberculata, from Asia in 1979. Centrocestus formosanus was first recorded in 1985 as metacercariae in fry of the first generation of black carp Mylopharyngodon piceus imported from China and subsequently in other fish from a farm in central Mexico. Since that time the trematode has spread rapidly over a wide area which includes central Mexico and both the Atlantic and Pacific coasts. This rapid spread has apparently been enabled by previous propagation of M. tuberculata in Mexico. Metacercariae of C. formosanus occur encysted on the gills of fish. They have been found in 39 species of fish of the families Atherinidae, Characidae, Cichlidae, Cyprinidae...
100 citations
TL;DR: Findings show that birds in coastal South Carolina use the tallow tree heavily as a food resource and are not generally saturated by present levels oftallow tree seed availability, as well as being an excellent predictor of the number of seeds dispersed in both habitats.
Abstract: We used seed traps (n = 119) to quantify seed dispersal of the Chinese tallow tree (Sapium sebiferum (L.) Roxb.) by birds in South Carolina during the October 1995 to April 1996 fruiting season. We tested if crop size, habitat type (spoil area vs. forest) and tree distribution (isolated vs. clustered) affected the dispersal efficiency and number of seeds dispersed from tallow trees. Traps captured 55,275 seeds and 107,993 functional locules; birds removed 48.8% of the available seeds. After scaling for canopy area of sample units (1570 m2; n = 32), birds removed an estimated 675,000 ± 56,000 of 1,681,000 ± 113,000 seeds, about 40% of the total seed crop. There was a trend for forest units to have greater dispersal efficiency than spoil area units but isolated and clustered trees were similar. Crop size was not a significant predictor of dispersal efficiency in either habitat but was an excellent predictor of the number of seeds dispersed in both habitats. The most productive unit was the only one...
86 citations
TL;DR: In this article, the authors used white polyvinyl chloride (PVC) pipes to capture hylids and determined how pipe design and placement influenced the frequency with which hyls used pipes as retreats.
Abstract: We used retreats made from white polyvinyl chloride (PVC) pipes to capture hylids and determined how pipe design and placement influenced the frequency with which hylids used pipes as retreats. Pipes were hung vertically in trees on three sites in north-central Florida. Pipes were checked twice weekly for 10 mo during which 788 individuals of four species (Hyla squirella, H. cinerea, H. femoralis and H. gratiosa) were captured, with 2658 recaptures. Retreats on hardwoods were used significantly more than retreats on pines, and retreats hung at 2 m and 4 m aboveground were used significantly more than retreats at 0 m. Long and T shaped retreats (both 60 cm long) were used significantly more than short (30 cm) retreats. Retreats capped on the bottom with water inside and 3.81 cm in diameter were used more frequently than retreats of the same diameter that were either capped on the top or not capped and retreats 1.75 cm in diameter with no cap.
79 citations
TL;DR: This paper used VHF, GPS and satellite radiocollars to study details of long distance movements by four Minnesota wolves (Canis lupus) and found that the number of locations during their tracking ranged from 14 to 274.
Abstract: We used VHF, GPS and satellite radiocollars to study details of long distance movements by four Minnesota wolves (Canis lupus). Number of locations during our tracking ranged from 14 to 274. Farthest distances reached ranged from 183–494 km, and minimum distances traveled (sums of line segments) ranged from 490–4251 km. Numbers of times wolves crossed state, provincial or interstate highways ranged from 1 to 215. All four of the wolves returned to or near their natal territories after up to 179 d and at least two left again.
TL;DR: In this article, the effects of different types of human activity on populations of medium-sized mammals were examined by counting road kills in the Central Valley of California, where the mean number of road kills recorded from July 1997 to August 1999 was 1.2/100 km, most being black-tailed jackrabbits.
Abstract: Effects of different types of human activity on populations of medium-sized mammals were examined by counting road kills in the Central Valley of California. The mean number of road kills recorded from July 1997 to August 1999 was 1.2/100 km, most being black-tailed jackrabbits (Lepus californicus). Road kills showed no marked seasonal trends. For some species habitat type influenced where carcasses were located, carnivores being found predominantly in rural habitats. For other species, such as Virginia opossums (Didelphis virginiana), domestic cats (Felis catus) and rats (Rattus rattus), carcasses were located in both rural and suburban landscapes. Some important assumptions notwithstanding road kill data can be effective in discerning how mammals are influenced by different types of land use.
TL;DR: The hypothesis that livestock grazing leads to a shift from grassland to shrubland in the Chihuahuan Desert, with associated changes in the structure and functioning of faunal communities, is supported.
Abstract: Livestock effects on plant communities through overgrazing (desertification) should affect the structure and functioning of semarid rangeland communities. We measured plant, granivorous ant and rodent communities and rates of seed removal by rodents and ants in grazed (by livestock) and ungrazed desert grasslands as well as mesquite and creosotebush shrublands to test hypotheses on the effects of grazing and desertification on ecosystem structure and functioning. In desert grasslands grazing reduced the cover of perennial grasses, particularly the dominant Bouteloua eriopoda, but the cover of forbs and shrubs did not differ between treatments. One species of perennial grass, Dasyochloa pulchellum, increased in grazed grasslands compared with grassland exclosures. Detrended correspondence analysis showed that grazing caused desert grasslands to shift in community structure towards the shrublands. There were more seed harvesting ant and rodent species in the creosotebush shrublands than in the gras...
TL;DR: Spruce-Fir or mixed spruce-fir/hardwood stands are important foraging sites for northern flying squirrels in the southern Appalachians, and micro- and macrohabitat characteristics associated with sample plots and sites are measured.
Abstract: Sporocarps of hypogeous mycorrhizal fungi (truffles) are the major food of northern flying squirrels (Glaucomys sabrinus). The two subspecies of northern flying squirrels that occur in the southern Appalachians, G. s. coloratus and G. s. fuscus, are endangered species which are primarily found in the ecotone between high-elevation spruce-fir and northern hardwood forests. Our objective was to determine the microhabitat and macrohabitat characteristics associated with the presence and abundance of truffles in suitable habitat for northern flying squirrels. We sampled for truffles in 24–26, 1-m2 plots on each of 10 northern flying squirrel sites in North Carolina and measured micro- and macrohabitat characteristics associated with sample plots and sites. Elaphomyces granulatus was the most common species of truffle found (78.7%). Red spruce (Picea rubra) was significantly more likely to be one of the three closest trees to plots with truffles. Further, spruce was the most important species in plots...
TL;DR: This paper examined changes in forests of the Luce District in Upper Michigan over the past 150 y and found that the presettlement landscape was a mixed conifer matrix (39% of total area), interspersed primarily with northern hardwoods (29%), wetlands (14%), and fire-susceptible pinelands (13%).
Abstract: General Land Office (GLO) survey notes (1840–1856), current land cover generated from Landsat TM Imagery (1991) and the Forest Inventory and Analysis plots (1991–1992, US Forest Service) were used to examine changes in forests of the Luce District in Upper Michigan over the past 150 y. Historical changes in two subdistricts, Grand Marais and Seney, were also analyzed. Interpretation of GLO notes showed that the presettlement landscape was a mixed conifer matrix (39% of total area), interspersed primarily with northern hardwoods (29%), wetlands (14%) and fire-susceptible pinelands (13%). Estimates of pre-European settlement stand density ranged from 81 trees/ha in open lands to 408 trees/ha in northern white cedar stands (Thuja occidentalis), and estimates of basal area ranged from 3.5 m2/ha in wetlands to 27.7 m2/ha in mixed hardwood/conifer forests. Notable changes in species composition over the last 150 y are the increase of red maple (Acer rubrum; +14%) and the decline of tamarack (Larix lari...
TL;DR: Age structures indicated that recruitment into the seedling bank was variable with time, but that individuals of both species occurred in almost all 5-y age classes, and allometric relationships differed significantly between species; spruce had a much greater height/diameter ratio than fir.
Abstract: We examined the dynamics of the tree-seedling bank in old-growth, subalpine Picea engelmannii—Abies lasiocarpa forests in south-central British Columbia by collecting all individuals <1.3 m tall within belt transects at two sites (n = ca. 500 per site) and determining their height, basal diameter and age. Seedlings were up to 149 y old. Regressions showed that spruce 1-m tall averaged 65-y old and fir 92-y old. Age structures indicated that recruitment into the seedling bank was variable with time, but that individuals of both species occurred in almost all 5-y age classes. Regressions of height and diameter vs. age had high predictability and showed that spruce grew more rapidly than fir. Allometric (height/diameter) relationships differed significantly between species; spruce had a much greater height/diameter ratio than fir. Seedlings accumulate gradually and persist for long periods in the seedling bank, thus forming a large pool of individuals that can potentially respond to opening of the c...
TL;DR: In this paper, the authors evaluated the effects of muskrat disturbance on plant biomass, species richness and diversity, stem density and potential net nitrogen mineralization and nitrification rates in a freshwater tidal marsh on the Hudson River in New York.
Abstract: The muskrat (Ondatra zibethicus) is a wetland mammal whose disturbance activities include grazing, burrowing and lodge construction. We evaluated the effects of these disturbances on plant biomass, species richness and diversity, stem density and potential net nitrogen mineralization and nitrification rates in a freshwater tidal marsh on the Hudson River in New York. We hypothesized that muskrats increase floristic richness and diversity by decreasing the biomass of narrowleaf cattail (Typha angustifolia) and that muskrats increase potential net nitrogen mineralization and nitrification rates through aeration and reduced plant uptake because of herbivory. Because muskrats commonly build lodges on or close to creek banks, we separated the disturbance effects of muskrats from the disturbance effects of the creek bank by sampling quadrats along transects placed perpendicular to creek banks at lodge sites. Muskrats decreased biomass, particularly of cattail, but had no measurable effect on stem count...
TL;DR: It is shown that direct attachment is a very important component of the effect of zebra mussel populations on unionids, and that they were starving, relative to noninfested individuals from the same location.
Abstract: We compared the physiological status and biochemical composition of unionid mussels (Amblema plicata) from a riverine population with and without attached zebra mussels (Dreissena polymorpha). Unionid specimens were collected from Lake Pepin, Mississippi River, WI and MN, where both infested and noninfested unionids were experiencing local increases in water clarity. Infested specimens had higher ammonia excretion rates, lower respiration to nitrogen excretion ratios and lower clearance rates than noninfested specimens. Infested specimens also had lower carbohydrate and protein contents. Zebra mussel infested unionids had depleted energy stores and we hypothesize that they were starving, relative to noninfested individuals from the same location. This comparison helps to clarify the nature of zebra mussel impacts on unionids by showing that direct attachment is a very important component of the effect of zebra mussel populations on unionids.
TL;DR: Feeding trials conducted with female harvestmen revealed that these arachnids were not capable of subduing live earthworms, suggesting that consumption of these in the field might be limited to scavenging.
Abstract: We gathered dietary data for several harvestman species in a soybean field and adjacent hedgerow habitats to assess the extent of their polyphagy. A total of 1032 harvestmen, predominantly Leiobunum spp., were observed during almost 50 search hours over two seasons. More harvestmen and increased foraging activity were observed in the hedgerow than in the soybean field, and in both habitats harvestmen were more active at night. Earthworms (Oligochaeta: Lumbricidae) were the prey items most frequently recorded as being consumed by all observed harvestman species in both habitats (47.1%), while fruit and other plant material constituted 18.1% of the records. Feeding trials conducted with female harvestmen, Hadrobunus maculosus (Wood), revealed that these arachnids were not capable of subduing live earthworms, suggesting that consumption of these in the field might be limited to scavenging. Implications of harvestman foraging for local food web dynamics are discussed.
TL;DR: Most big brown bats in Indiana hibernate in heated buildings rather than in caves or mines, and the sex ratio of hibernating bats was male biased in buildings with maternity colonies and female biased in Buildings lacking maternity colonies.
Abstract: We monitored 63 buildings in Indiana serving as hibernacula for big brown bats for up to six winters. Fidelity of individuals to roosts averaged 21.4% in buildings with maternity colonies and 33.3% in buildings without maternity colonies, although this difference was not significant. There was much turnover, both within and among years, some bats being present one year, absent for a year or two and then returning. The sex ratio of hibernating bats was male biased (65.6% males) in buildings with maternity colonies and female biased in buildings lacking maternity colonies (65.2% female). Most big brown bats in Indiana hibernate in heated buildings rather than in caves or mines.
TL;DR: Demographically complete sampling of a large population of Fusconaia ebena (Lea) in a mainstream shoal in the lower Ohio River from 1983 through 1998 revealed two extremely successful recruitment years—1981 and 1990.
Abstract: Demographically complete sampling of a large population of Fusconaia ebena (Lea) in a mainstream shoal in the lower Ohio River (LOR) from 1983 through 1998 revealed two extremely successful recruitment years—1981 and 1990. Dominance of the 1981 and 1990 cohorts allowed length-to-age relationships to be estimated directly from length-frequency histograms. Two linear relationships adequately described growth rates from age 2 through 17 y. The first model applied to ages 2 through 10 y when annual growth averaged 6.1mm. The second model applied to ages 10 through 17 y when annual growth averaged only 1.1 mm. A survivorship curve was based on density of the 1981 cohort from age 2 through 17 y. During that period a constant proportion (17%) of the cohort died each year. Only 9% of the 1981 cohort alive in 1983 were still alive in 1998. In both 1981 and 1990 rapid and large spring rises in LOR discharge were immediately followed by rapid and large declines. These rises coincided with the expected spawn...
TL;DR: The structure and dynamics of the woods are very similar to other old-growth beech-sugar maple forests of the region, however, the number of large beech stems has been declining steadily even though beech bark disease has not yet reached the area.
Abstract: The objective of this study was to establish baseline data for the structure and dynamics of an old-growth beech (Fagus grandifolia)-sugar maple (Acer saccharum) woods in northeastern Ohio before the anticipated future impacts of disturbances such as beech bark disease. Several parameters were selected for study based on their likelihood of being influenced by these disturbances including: (1) species composition; (2) mortality and growth rates of trees, overall, by species and by size class; (3) canopy replacement patterns; (4) coarse woody debris (CWD) characteristics; and (5) the understory response to existing openings and its implications for change in the forest under present conditions. This study extends our understanding of beech-sugar maple old growth because our site is, perhaps, the most northeasterly one not yet affected by beech bark disease and because it is the only studied site influenced by weather conditions generated by Lake Erie. The overall annual mortality rate (from 1992 t...
TL;DR: Comparison of nectar plant selections at Indiana Dunes National Lakeshore to selections from Michigan and Wisconsin suggests that the Karner blue most frequently chooses a suite ofnectar plant species that includes A. lyrata, C. lanceolata, Euphorbia corollata, M. alba, Monarda punctata, Potentilla simplex, Rubus spp.
Abstract: The Karner blue butterfly, Lycaeides melissa samuelis, is an endangered species residing in savanna and barrens habitats in the Midwest and Northeast United States. To improve our understanding of nectar plant selection patterns by the Karner blue, we examined nectar plant choices made by 146 butterflies. Within observation areas of 2-m radius butterflies usually chose the nectar species with the greatest total number of flowers or flowering heads. This suggests that the Karner blue is opportunistic in selecting nectar plants. However, certain nectar species, including Arabis lyrata, Coreopsis lanceolata, Melilotus alba and Rubus flagellaris, were selected in a significant majority of cases when other nectar species were available nearby. At least in the case of R. flagellaris, this preference was not directly related to the species' local flower abundance. In a significant majority of cases (77.5%) adult Karner blues selected nectar plant species with yellow or white flowers over species with ot...
TL;DR: Spawning behaviors were filmed and observed in the nest-building minnows, the bluehead chub, Nocomis leptocephalus, and river chub and male central stoneroller, Campostoma anomalum to facilitate interspecific comparisons.
Abstract: Spawning behaviors were filmed and observed in the nest-building minnows, the bluehead chub, Nocomis leptocephalus, and river chub, N. micropogon. Analysis of videotapes exposed previously unreported behaviors (e.g., female retroflexure) and a precise sequence of male-female interactions that coordinated a successful spawn. Reproductive behaviors were classified into six sequential categories (interim, approach, alignment, run, clasp, dissociation) to facilitate interspecific comparisons. The most conspicuous differences between species involved the intensity of the female's retroflexure and the male's spawning clasp (strong in N. leptocephalus vs. weak in N. micropogon) and reproductive behaviors of subordinate males. In N. leptocephalus, subordinate males spawned concurrently and independently of the resident male over a communal nest, whereas in N. micropogon a subordinate acted like a satellite male and stole spawns from the nest-building male. In addition, heterogeneric spawning clasps invol...
TL;DR: Although probably opportunistic, deer predations clearly were deliberate and likely are more common than generally believed.
Abstract: White-tailed deer (Odocoileus virginianus) were videotaped depredating four songbird nests in grassland habitats in southeastern and northcentral North Dakota, 1996–1999. Deer ate two Savannah sparrow (Passerculus sandwichensis), two grasshopper sparrow (Ammodramus savannarum), one clay-colored sparrow (Spizella pallida), one red-winged blackbird (Agelaius phoeniceus) and three brown-headed cowbird (Molothrus ater) nestlings. Deer removed nestlings quickly (5–19 sec/nest) at night (22:00 to 05:17 Central Daylight Time) and left no evidence of predation. Although probably opportunistic, deer predations clearly were deliberate and likely are more common than generally believed.
TL;DR: In this paper, the authors quantified swimming endurance and behavior for Topeka shiners in a laboratory swim tunnel and found that larger individuals (4.4-5.5 cm) exhibited greater sustained swimming ability than smaller individuals (3.0-4.2 cm standard length).
Abstract: The Topeka shiner (Notropis topeka) is imperiled by extensive changes in stream hydrology. Responses of shiners to changes or variation in stream hydraulics, however, have not been quantified, hampering conservation efforts. We quantified swimming endurance and behavior for Topeka shiners in a laboratory swim tunnel. Sustained swimming (>200 min) was observed at water velocities of 30–40 cm/s. Prolonged and burst swimming (approximately 10 min to less than 0.1 min) was observed at water velocities of 40–75 cm/s and endurance was negatively correlated with water velocity. Larger individuals (4.4–5.5 cm standard length) exhibited greater sustained swimming ability than smaller individuals (3.0–4.2 cm standard length). Oral grasping of wire mesh within the swim tunnel was frequently employed at moderate water velocities (35–50 cm/s); this behavior may limit downstream displacement of shiners during freshets. Topeka shiners are capable of swimming speeds faster than water velocities which they typica...
TL;DR: In this article, the authors used a simulation model with the same number of fields and field sizes as those examined in earlier studies to determine if birds that select habitat randomly would display area sensitivity if fields were sampled in proportion to their size.
Abstract: Several studies have reported that some grassland birds are area sensitive; they exhibit a nonrandom avoidance of small fields. The methods used to test for area sensitivity, however, differed among studies. Some investigators sampled fields with sampling effort proportional to field size, whereas others used equal sampling effort in all fields. We created a simulation model with the same number of fields and field sizes as those examined in earlier studies to determine if birds that select habitat randomly would display area sensitivity if fields were sampled in proportion to their size. The three species that we modeled to settle randomly, upland sandpiper (Bartramia longicauda), Henslow's sparrow (Ammodramus henslowii) and eastern meadowlark (Sturnella magna), had positive relationships between occurrence and field size when a complete census or proportional sampling was used, and therefore, would have been considered area sensitive by the methods used by some previous authors. When equal-effo...
TL;DR: Results suggest that conservation efforts must consider seed storage conditions, genetic source of seeds and seed size, as well as maintenance of natural sand erosion and accretion regimes for preservation and restoration of this taxon.
Abstract: Pitcher's thistle (Cirsium pitcheri) is a federally listed monocarpic plant species endemic to the shoreline dunes of Lakes Huron, Michigan and Superior. Individual plants may require 4–8 y to mature, after which they flower and die. This life history and the lack of vegetative modes of reproduction make an understanding of seed and seedling ecology critical for preservation and restoration of Pitcher's thistle. We report conditions necessary to overcome seed dormancy and the effects of light, seed mass and depth of burial (0, 2, 4 or 8 cm) on seed and seedling success from laboratory experiments in controlled growth environments. Seeds of Pitcher's thistle are dormant when dispersed, but a combination of low temperatures and afterripening can break dormancy. Germination over 30% was obtained with at least 24 wk of low temperature moist stratification; 25% germination occurred after 6 mo of storage at room temperatures. Light suppressed germination of nondormant seeds. Although burial is required...
TL;DR: Overall lower abundance and H′ values in the summers of 1994–1996 compared with 1977–1978 may be the result of habitat alteration during the restoration of the Carolina bay.
Abstract: We determined the relative abundance, days of surface activity and indices of species diversity, evenness and richness for amphibians inhabiting three differently managed forests surrounding a Carolina bay in South Carolina following restoration. We collected animals daily for 3 y (Oct. 1993–Sept. 1996) using drift fences with pitfall traps in three forest types: loblolly pine (Pinus taeda), slash pine (P. elliotti) and mixed hardwoods (predominantly oak, Quercus spp. and hickory, Carya spp.). Captured animals were marked and recaptures were recorded but not included in statistical analyses, except in our evaluation of activity. We compared results to those of a more limited study conducted before restoration. Amphibians were significantly more numerous and more active in the mixed hardwood forest than in the pine forest types. However, the hardwood forest had the lowest species diversity in 2 of the 3 y of the study. The slash pine habitat had the highest diversity in all 3 y and for the 3 y com...
TL;DR: Examination of aggressive behavior by adults of the Ozark zigzag salamander shows that both males and females defend feeding territories and that residency offers an advantage that is independent of fighting ability in this species.
Abstract: Once territories become established residents often have a high probability of successfully defending their territories against intruders. This advantage often can be explained by intrinsic qualities (e.g., size, body condition, experience) that make residents superior competitors. In addition, residency status can confer an advantage that is independent of fighting ability. We used a laboratory experiment to examine the effect of residency status on aggressive behavior by adults of the Ozark zigzag salamander (Plethodon angusticlavius), a small terrestrial salamander found under rocks and logs on the forest floor. We controlled for intrinsic effects by testing each individual as both a resident and an intruder in random order. Males and females were tested in same-sex contests in separate experiments. Based on an index that incorporated the frequency of aggressive and submissive postures, both males and females were significantly more aggressive as residents than as intruders. Bites were perform...