Showing papers in "American Midland Naturalist in 2007"
TL;DR: In this paper, the authors examined the spatial and temporal utilization and availability of natural and human-associated food for coyotes in the Chicago metropolitan area, Illinois, USA, and collected 1429 coyote scats from May 2000 to December 2002, and conducted prey surveys in 2002, in 4 sites that varied in their degree of urban development.
Abstract: Coyotes (Canis latrans) are an opportunistic predator that have adapted to many human-modified environments. Conflicts between coyotes and humans are an increasing concern for managers in urban areas. We examined the spatial and temporal utilization and availability of natural and human-associated food for coyotes in the Chicago metropolitan area, Illinois, USA. We collected 1429 coyote scats from May 2000 to December 2002, and conducted prey surveys in 2002, in 4 sites that varied in their degree of urban development. Dominant food items included small rodents, white-tailed deer (Odocoileus virginianus), fruit, eastern cottontail (Sylvilagus floridanus) and birds. Their availability and occurrence in scats varied among sites and seasons. The occurrence of human-associated food items, which was only found in significant amounts in the most developed site, varied seasonally (2–25%). Because coyotes in less-developed areas had lower dietary diversity, these coyotes may have to venture into develope...
155 citations
TL;DR: Compared the beetle fauna captured in 12 pairs of flight intercept traps suspended at two different heights above the ground 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 is understood.
Abstract: 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 a...
101 citations
TL;DR: In this article, the bait trade and anglers were surveyed to determine whether bait stores sell known invasive species and whether angler behavior is likely to lead to these species becoming introduced near lakes.
Abstract: 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 invasi...
65 citations
TL;DR: It is indicated that the use of enclosed track-plates is a powerful non-invasive technique for detecting eastern spotted skunks when surveys are conducted between late Sept. and early May, and surveys conducted during late spring and summers are inappropriate.
Abstract: The eastern spotted skunk (Spilogale putorius) is a rare species of conservation concern throughout much of its range, but effective management is hampered by a lack of information on appropriate survey strategies. We validated three commonly used techniques to identify the presence of eastern spotted skunks at four sites in Missouri and Arkansas where the species was known to occur. Live-capture with box-traps revealed a strong seasonal pattern in capture success in both states, with virtually all captures occurring between late Sept. and early May. This pattern of detection also occurred when surveys were conducted using non-invasive camera-traps and enclosed track-plates in Missouri. Track-plates were more efficient than camera-traps at detecting eastern spotted skunks, with a lower latency to initial detection (LTD) and higher probability of detection (POD). Our results indicate that the use of enclosed track-plates is a powerful non-invasive technique for detecting eastern spotted skunks when surveys are conducted between late Sept. and early May. Surveys conducted during late spring and summers are inappropriate given the high likelihood of not detecting the species despite its presence.
51 citations
TL;DR: The same fire regime that minimized woody plant invasion also maximized arthropod diversity, with Diptera and Homoptera exhibited particularly strong positive responses to fires and Lepidoptera had a negative response to nutrient enrichment.
Abstract: Fire is an important tool for limiting woody plant invasions into prairies, but using fire management to maintain grassland plant communities may inadvertently reduce arthropod diversity. To test this, we established twenty-four 100 m2 plots in a tallgrass prairie in Galveston County, Texas, in spring 2000. Plots were assigned a fire (no burn, one time burn [2000], two time burn [2000, 2001]) and fertilization treatment (none, NPK addition) in a full factorial design. Fertilization treatments allowed us to examine the effects of fire at a different level of productivity. We measured plant cover by species and sampled arthropods with sweep nets during the 2001 growing season. Path analysis indicated that fertilization reduced while annual fires increased arthropod diversity via increases and decreases in woody plant abundance, respectively. There was no direct effect of fire on arthropod diversity or abundance. Diptera and Homoptera exhibited particularly strong positive responses to fires. Lepido...
51 citations
TL;DR: In this article, the effects of burning and thinning on the microhabitat associations of flying squirrels were examined in mixed-conifer forests of the southern Sierra Nevada at the Teakettle Experimental Forest.
Abstract: Prescribed burning and mechanical thinning are used to manage fuels within many western North American forest ecosystems, but few studies have examined the relative impacts of these treatments on forest wildlife. We sampled northern flying squirrels (Glaucomys sabrinus) and microhabitat variables in burned, thinned and control stands of mixed-conifer forest of the southern Sierra Nevada at the Teakettle Experimental Forest. We used this information to determine the effects of burning and thinning on the microhabitat associations of flying squirrels. Across pretreatment stands, the probability of flying squirrel capture increased with decreasing distance to a perennial creek and increasing litter depth. The probability of flying squirrel capture also was greater with increased canopy cover in thinned stands and increased litter depth in burned stands. Greater canopy cover may provide protection from predators, thicker litter layers may harbor a greater abundance of truffles, a primary food of northern flying squirrels, and creeks may provide squirrels with food sources, drinking water and nest trees. Results from this study underscore the need for more information on the effects of forest management on northern flying squirrels near the southern extent of the species' geographic range.
50 citations
TL;DR: Control of high density deer populations will be more difficult where female dispersal is prevalent, as in the agriculturally dominated Midwest landscape.
Abstract: Dispersal behavior was examined for 119 male and 102 female white-tailed deer (Odocoileus virginianus) fawns marked in central and northern Illinois. Fawn movement behavior was recorded for 35 single, 78 pair and 10 triplet litters that survived intact beyond family breakup in late spring. Males (65%) dispersed at a higher rate than females (39%). Females dispersed Apr.–Jul., while males dispersed Apr.–Jul. and Sep.–Nov. The dam's and siblings movements most affected fawn movement behavior with most fawns of dispersing/migrating females and siblings leaving their natal range. As yearling-adult densities and forest cover increased on our study areas, female fawn dispersals decreased. Habitat scarcity in spring coupled with high fawn survival into the spring months promoted higher than expected female dispersal behavior. Distance traveled to a new range did not differ among study areas, years or month of dispersal for either sex. Single fawns were as likely to disperse as fawns from pairs or triple...
50 citations
TL;DR: It is found that females within localized subpopulations exhibited a higher degree of genetic structuring than males indicating female philopatry and male-biased dispersal, which is consistent with other studies on temperate vespertilionid bats.
Abstract: Sex-biased dispersal is a specific pattern of movement whereby one sex either stays or returns to its natal group or natal area to breed while the other disperses from the natal area. Temperate vespertilionid bats are thought to exhibit the typical mammalian pattern of male-biased dispersal although relatively few studies have been conducted on this group. The northern myotis (Myotis septentrionalis) is a relatively common forest dwelling bat found in eastern North America. Despite being a common species in North America, relatively little is known about its habitat requirements and life history characteristics including dispersal patterns. Using five polymorphic microsatellite loci I found that females within localized subpopulations exhibited a higher degree of genetic structuring than males indicating female philopatry and male-biased dispersal [female FST = 0.011; male FST = −0.016; P = 0.006 (sex-biased dispersal randomization test)]. I also found a weak (FST = 0.002), but significan...
47 citations
TL;DR: A year-long drift fence study of a species-rich herpetofaunal community surrounding an isolated wetland in the southeastern United States determined the effects that timing, trap type and taxon had on capture rates of her petofauna.
Abstract: 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 sea...
45 citations
TL;DR: These small mammal species responded neutrally or favorably to disturbance, and identified favorable microhabitat features regardless of stand type.
Abstract: Forestry practices result in a range of levels of disturbance to forest ecosystems, from clearcutting and deferment (high disturbance) to single-tree selection cutting and unharvested forests (low disturbance). We investigated the effects of timber harvest and disturbance on small mammal species in the Allegheny Mountains of West Virginia. In 2003 and 2004, mammals were captured using Sherman box traps, individually marked, and released. We collected habitat data in 2004 to characterize macrohabitat at the stand level and microhabitat surrounding each trap. Trap success was significantly higher in disturbed habitats than undisturbed habitats for red-backed vole Myodes (Clethrionomys) gapperi (P = 0.0012) and woodland jumping mouse Napaeozapus insignis (P = 0.0221). Abundance estimated using the Jolly-Seber method was significantly higher in disturbed habitats for red-backed voles (P = 0.0001). Adult northern short-tailed shrews Blarina brevicauda (P = 0.0001) and white-footed and deer mic...
45 citations
TL;DR: It appears that larger females split the increased reproductive allocation made possible by increased maternal volume devoted to eggs between increasing both clutch size and egg size, consistent with predictions of the anatomical-constraints hypothesis.
Abstract: According to optimal offspring size theory, natural selection pressures balance the egg size/clutch size trade-off at a point where increases in maternal body size result in increases in clutch size but not increases in egg size. However, many turtle species show increasing egg size with increasing maternal body size. The anatomical-constraints hypothesis explains this pattern by hypothesizing that smaller females lay smaller-than-optimal eggs because of morphological constraints; larger eggs simply would not pass through the pelvic aperture and caudal gap of the shell. We examined relationships among female body size (measured as plastron length), clutch size and egg size for a population of common map turtles (Graptemys geographica) at Presque Isle State Park in Erie, Pennsylvania. Correlation analyses were conducted using log-transformed data in order to address questions of isometry and allometry. Clutch mass increased isometrically with plastron length. Egg size and clutch size were both significantly negatively allometric in their relationship with plastron length. It appears that larger females split the increased reproductive allocation made possible by increased maternal volume devoted to eggs between increasing both clutch size and egg size, consistent with predictions of the anatomical-constraints hypothesis.
TL;DR: Bare patches of soil in the forest interior are colonization sites for invasive plant species, and small disturbances to the litter layer allow invasive species to become established in forest interiors are confirmed.
Abstract: 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 s...
TL;DR: Home range size and philopatry in ornate box turtles, Terrapene ornata ornata, with minimum convex polygons (MCP) and 95% Kernel areas (K) calculated from radio telemetry data in Iowa during 1999–2001 are quantified.
Abstract: We quantified home range size and philopatry in ornate box turtles, Terrapene ornata ornata, with minimum convex polygons (MCP) and 95% Kernel areas (K) calculated from radio telemetry data in Iowa during 1999–2001. We also analyzed philopatry by mark-recapture data during 1994–2000. Ten adult turtles were followed every other day from May to Sep. 2000 and seven of the turtles were followed in 2001. Mean monthly MCP and K home ranges of males and females did not significantly differ. Mean annual MCP and K home ranges for males were significantly larger than those of females. For an individual, monthly MCP home ranges overlapped on average 19.3% between years and K home ranges overlapped an average of 6.0%. There were no significant differences in annual or monthly home range overlap between sexes for K home ranges, but MCP monthly home range overlap was significantly larger for males. Annual MCP home ranges overlapped on average 40.9% between years and K annual home range overlap averaged 6.8%. S...
TL;DR: Report of parasitism rates by this tachinid fly in wild captured monarchs, using data collected over 7 y by 77 volunteers in the Monarch Larva Monitoring Project, suggests that females either respond to larger hosts by laying more eggs or that superparasitism (parasitic by more than one individual) occurs.
Abstract: Lespesia archippivora is a widespread generalist parasitoid whose hosts include monarch butterfly larvae. We report parasitism rates by this tachinid fly in wild captured monarchs, using data collected over 7 y by 77 volunteers in the Monarch Larva Monitoring Project, a North American Citizen Science Program. Data were collected in 21 U.S. states and one Canadian province, with focus sites in Wisconsin, Michigan and North Carolina. Overall, approximately 13% of monarch larvae contained tachinid flies. Parasitism rates varied by year, and this variation was, to a large extent, region-wide. For example, larvae collected in 2000–2002 throughout the Upper Midwestern U.S. suffered significantly more parasitism than those collected in 1999 or 2003–2005. There were no consistent patterns with respect to date of collection within years. The number of flies per parasitized monarch ranged from one to 10 and comparison to a Poisson distribution indicated that flies were more aggregated within hosts than exp...
TL;DR: In this article, the authors assessed the species composition and biomass and nutrient contributions of summer ground layer vegetation to the above-ground litter pool at the AmeriFlux Site in the Morgan-Monroe State Forest, Indiana.
Abstract: Eastern deciduous forests of North America have productive ground layers, but information regarding the role of ground layer vegetation in carbon cycling is limited. The ground layer, here defined as all vascular plants ≤1 m in height, contributes most of its biomass and nutrient content annually to the above-ground litter pool. This study assessed the species composition and biomass and nutrient contributions of summer ground layer vegetation to the above-ground litter pool at the AmeriFlux Site in the Morgan-Monroe State Forest, Indiana. Two hundred fifteen 1-m2 subplots were sampled for ground layer species and cover (%). Forty-three of those subplots were harvested for above-ground biomass and tissue nutrient analysis. A 10-cm soil sample was obtained from each harvested subplot and analyzed for pH, organic matter and nutrient content. Boehmeria cylindrica (false nettle), Lindera benzoin (spicebush), Viola spp. (violets), Parthenocissus quinquefolia (Virginia creeper), Polystichum acrostichoi...
TL;DR: The effects of the removal of Hedera helix (English ivy) on regeneration of native vegetation in the Piedmont of Georgia and the addition of native seed are examined to suggest that the method of exotic plant removal and the Adding native seed can have profound effects on the regeneration ofnative vegetation.
Abstract: Invasive plants can have substantial negative impacts on native flora and fauna. As a result, ecological restoration often involves removal of invasive species. We examined the effects of the removal of Hedera helix (English ivy) on regeneration of native vegetation in the Piedmont of Georgia. Ivy was removed by hand or by herbicide from five 5 m × 5 m plots for each treatment and half of each plot was seeded with native seeds. We then counted the number of seedlings present in each plot bimonthly over a 5-mo period. Ivy removal by pulling resulted in the greatest density and diversity of seedlings. Furthermore, these plots exhibited increased seedling density and diversity due to seed addition. Spraying was effective in removal of the ivy but significantly lowered seedling density and diversity and hindered any seed addition efforts. Control plots in which ivy was not removed had no seedlings germinate. Our results suggest that the method of exotic plant removal and the addition of native seed c...
TL;DR: Whether the timing of herbivory by white-tailed deer affects the population dynamics of the long-lived herb, Trillium grandiflorum, is examined to determine how both the frequency and timing of Herbivory alter the population growth rate.
Abstract: The timing of herbivory may have important consequences to components of plant fitness as well as the growth rate and persistence of plant populations. Specifically, this study examines whether the timing of herbivory by white-tailed deer (Odocoileus virginianus) affects the population dynamics of the long-lived herb, Trillium grandiflorum. This study combines results from a clipping experiment with demographic matrix modeling in four different T. grandiflorum populations to determine how both the frequency and timing of herbivory alter the population growth rate. Herbivory early, but not late in the season, increased the probability that reproductive plants fail to reproduce in the next year. Both early and late season herbivory resulted in a complete loss of reproductive success in the current year. Because the growth rates of these populations were sensitive to changes in the fate of reproductive plants, but insensitive to changes in annual fecundity, early season herbivory was more detrimental to population growth rates than late season herbivory. Plant persistence may depend as much on the timing of herbivory as it does its frequency.
TL;DR: Overall, mussel assemblages in the Black River appear typical for the region with relatively abundant, but low diversity communities upstream of the cities that line Lake Erie's coast and diverse, but small and potentially threatened, populations in the urban regions.
Abstract: Habitat destruction is believed to be the number one cause of the decline in unionid mussels. Around the world, cities, towns and agriculture alter the structure of watersheds, and the Black River in Ohio may be a typical example. We investigated the diversity and abundance of unionid mussels in this watershed and compared results to urbanization locations, to site-specific appearance of the habitat and to a 1997 fish survey, as host species are another factor important to the distribution of unionid mussels. Although shells were found for 21 species, only 11 of these species were found alive. Seven of the species represented only by shells occurred only in the urbanized lower main stem of the river and less than five shells were found for each. Most of these shells were old and worn. Furthermore, the present assemblage in the main stem varied from shells obtained at a nearby archeological site, and from a voucher set of species obtained at the turn of the 20th Century. Mussel communities higher in the river and those in tributaries were less diverse, but abundance of the species present was higher than in the main stem. A lack of fish hosts may limit mussel diversity, as hosts for several species present in the main stem do not reside higher in the watershed. Overall, mussel assemblages in the Black River appear typical for the region with relatively abundant, but low diversity communities upstream of the cities that line Lake Erie's coast and diverse, but small and potentially threatened, populations in the urban regions.
TL;DR: L. borealis foraged in woodlands and over newly planted tree fields, open water, park and pasture lands more than predicted by randomly generated points and avoided highly urban areas such as commercial lands, gravel pits and transportation corridors.
Abstract: We captured female Lasiurus borealis near the Indianapolis International Airport during summers of 2003 and 2004 and radiotracked them during foraging. We obtained complete foraging data on 13 bats. A series of multi-azimuth (3–7) triangulations was used to estimate the location of each bat throughout the night. Distance based analysis was used to examine habitat use by L. borealis. Lasiurus borealis had both smaller home ranges than previously noted and smaller home ranges than other species at this location. Lasiurus borealis foraged in woodlands and over newly planted tree fields, open water, park and pasture lands more than predicted by randomly generated points and avoided highly urban areas such as commercial lands, gravel pits and transportation corridors.
TL;DR: This article found that the amount of edge habitat in an area may be an important factor in determining home range size of pumas, regardless of the size of the home range and there would be more edge habitat within home range boundaries than in general areas of similar size.
Abstract: Results of recent studies have indicated that the amount of edge habitat in an area may be an important factor in determining home range size of pumas. We tested this hypothesis with data on home ranges of pumas in southern Idaho/northwestern Utah. The study area is highly fragmented into forest patches and sagebrush open areas. We tested three predictions: (1) the percent of edge would be negatively related to home range size, (2) the amount of edge habitat in the home ranges of pumas would be similar, regardless of the size of the home range and (3) there would be more edge habitat within home range boundaries than in general areas of similar size. Home range size (90%) varied from 29.8 to 118.7 km2. The percent of edge within home ranges was negatively correlated with home range size (F = 22.3, P < 0.001, R2 = 0.53), but amount of edge habitat within the home ranges was not. The mean percent of edge within home range boundaries (16.0 ± 1.4 (se) %) was significantly greater (t = 2.88, P ...
TL;DR: Pitcher size was significantly positively related to total mass of prey capture per day, explaining 37–76% of the variation depending on the population, and the sugar concentration in nectar and the red coloration as the authors measured them were not important in determining prey capture.
Abstract: 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.
TL;DR: Two hundred and thirty-seven species of macrofungi and 465 species of vascular plants were identified from seven selected permanent sites and species diversity of all plants and all fungi at the sites had a very significant correlation.
Abstract: Two hundred and thirty-seven species of macrofungi and 465 species of vascular plants were identified from seven selected permanent sites. Areas of permanent sites ranged from 0.5 to 10.8 ha. No fungal species were collected from all sites and 126 (53%) were collected from only one site. Fourteen fungal species (6%) were collected each year of the study and 116 (49%) were collected only 1 y. Numbers of newly collected fungal species from the seven sites did not decrease each year of the study. Classifying fungal genera by nutritional group showed 36% of the genera collected were terricolous, 53% lignicolous, 16% ectomycorrhizal and 5% parasites. Nine plant species were collected from all sites, while 232 (50%) were collected at only one site. Fifteen plant species on the sites are on the state list of rare, threatened and endangered species. Botany Bay, a narrow moist canyon with dense vegetation dominated by Picea glauca, Ostrya virginiana, Betula papyrifera and Pinus ponderosa, had the highest ...
TL;DR: 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 game bird chicks.
Abstract: 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 ex...
TL;DR: In this article, the influence of habitat factors on DRS selection of raccoons in the Mississippi River bottomlands of southern Illinois was studied, where 54 adult females were equipped with radiocollars and were tracked to 313 DRS.
Abstract: Although much is known about raccoon (Procyon lotor) denning ecology, little information is available regarding habitat correlates to raccoon daytime resting site (DRS) selection at multiple spatial scales. We studied the influence of habitat factors on DRS selection of raccoons in the Mississippi River bottomlands of southern Illinois. During 2003–2005, 54 adult females were equipped with radiocollars and were tracked to 313 DRS. Using field measurements and remotely sensed data, 156 microhabitat (e.g., den height) and macrohabitat (e.g., forest patch size) variables were measured at: (1) breeding season DRS (1 Dec.–1 Mar.), (2) cub-rearing season DRS (15 Mar.–30 Jun.) and (3) control locations. Tree cavities represented 73% of DRS; the remaining 27% were more exposed DRS. A 5-variable multinomial logistic regression model incorporating tree circumference at breast height, den height, distance to nearest road, distance to nearest water and number of nearby dens was significant (P < 0.001) and co...
TL;DR: The nesting chronology, nest site selection and nest success of smallmouth bass Micropterus dolomieu in an upstream and downstream reach of Baron Fork Creek, Oklahoma suggest that biological factors account for most nest failures during benign streamflow conditions, whereas nest failures attributed to substrate mobility or nest abandonment dominate when harsh stream flow conditions coincide with the spawning season.
Abstract: We documented the nesting chronology, nest site selection and nest success of smallmouth bass Micropterus dolomieu in an upstream (4th order) and downstream (5th order) reach of Baron Fork Creek, Oklahoma. Males started nesting in mid-Apr. when water temperatures increased to 16.9 C upstream, and in late-Apr. when temperatures increased to 16.2 C downstream. Streamflows were low (77% upstream to 82% downstream of mean Apr. streamflow, and 12 and 18% of mean Jun. streamflow; 47 and 55 y of record), and decreased throughout the spawning period. Larger males nested first upstream, as has been observed in other populations, but not downstream. Upstream, progeny in 62 of 153 nests developed to swim-up stage. Downstream, progeny in 31 of 73 nests developed to swim-up. Nesting densities upstream (147/km) and downstream (100/km) were both higher than any densities previously reported. Males selected nest sites with intermediate water depths, low water velocity and near cover, behavior that is typical of smallmouth bass. Documented nest failures resulted from human disturbance, angling, and longear sunfish predation. Logistic exposure models showed that water velocity at the nest was negatively related and length of the guarding male was positively related to nest success upstream. Male length and number of degree days were both positively related to nest success downstream. Our results, and those of other studies, suggest that biological factors account for most nest failures during benign (stable, low flow) streamflow conditions, whereas nest failures attributed to substrate mobility or nest abandonment dominate when harsh streamflow conditions (spring floods) coincide with the spawning season.
TL;DR: An increase in amphibian species diversity in experimental ponds following the removal of fish and temporal changes in smallmouth salamander population dynamics suggest that amphibian communities are capable of recovering from environmental perturbations.
Abstract: Introduced species have become one of the most important anthropogenic impacts in aquatic ecosystems and are implicated in the declines of many native amphibian populations. Despite the effects of introduced fish species on amphibian communities, there is little information concerning the responses of amphibians following the removal of introduced predatory fish. We present results of a 4-y field experiment designed to determine the amphibian community- and population-level responses to the removal of introduced predatory fish from two experimental ponds. We observed an increase in amphibian species diversity in experimental ponds following the removal of fish. We also observed temporal changes in smallmouth salamander (Ambystoma texanum) population dynamics. Although A. texanum size at metamorphosis was unaffected by introduced fish in experimental ponds, fish removal resulted in prolonged A. texanum larval period and improved reproductive success. We attribute these responses to increases in A....
TL;DR: The estimated home-range size for American marten in northern Wisconsin during the winter months of 2001–2004 and the proportion of cover-type selection categories (highly used, neutral and avoided) among home-ranges, core areas, and the study area suggest that American martens select core areas based upon micro-site features rather than broad-scale cover types.
Abstract: 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 habit...
TL;DR: Beech, in particular, showed large increases in mortality, probably due to the growing impact of beech bark disease, which reached the stand about 1990, and which species will replace beech in the canopy is difficult to predict.
Abstract: Old-growth stands within the Tionesta Research Natural Area were sampled in 1977, 1990 and 2000. Sapling growth within 25 treefall gaps was sampled all three times. Canopy trees were measured using the point-centered quarter method, with 83 points sampled all three times. Gap regeneration increased significantly in density and basal area from 1977–1990. Beech (Fagus grandifolia) significantly increased its relative gap sapling density from 68% to 91% to 94% over the 3 y. Other species decreased in absolute numbers presumably due to deer browsing. Canopy tree density remained constant and basal area increased 1977–1990 but both decreased 1990–2000. Species relative density and basal area values did not change. Mortality rates almost doubled from 1977–1990 to 1990–2000, increasing especially for smaller canopy trees. Snag densities and formation rates also increased, though not significantly, from the first to the second time interval. Beech, in particular, showed large increases in mortality, prob...
TL;DR: The similarity in diets between coyotes and swift foxes indicated the potential for resource competition between these species, although the authors did not determine food availability.
Abstract: Predation by coyotes (Canis latrans) has been documented as the main cause of mortality in most populations of swift foxes (Vulpes velox), although reasons for such high predation rates were often unclear. Additionally, coyotes kill but generally do not consume swift foxes, suggesting coyotes kill for reasons other than food. To better understand ecological relationships between these species, we studied dietary overlap of syntopic coyotes and swift foxes in northwestern Texas from 1998 to 2000. Both species consumed the same food items and had similar seasonal changes in diets, although the order of these items differed for each species. Overall, coyotes and swift foxes had high dietary overlap (Ro = 0.856), although some dietary partitioning was evident based on food size categories. Dietary overlap was least in summer (Ro = 0.714) and greatest in winter (Ro = 0.859). Swift fox diets were dominated by small food items (i.e., rodents and insects), whereas coyote diets had nearly equal repr...
TL;DR: In this paper, the authors investigated the spatial relationships of cerulean warblers at Big Oaks National Wildlife Refuge, Madison, Indiana, during the summers of 2002 and 2003, and used a nearest neighbor analysis for the spatial placement of the centroids of the colonies of Dendroica cerulea.
Abstract: Territorial spacing is an aspect of songbird territoriality which is easily investigated, though often ignored. Cerulean warblers (Dendroica cerulea) maintain all-purpose breeding territories in eastern North American deciduous forest. Many observers have noted that cerulean warblers may breed in clusters of territories, but this information has not been determined statistically. We investigated the spatial relationships of cerulean warblers at Big Oaks National Wildlife Refuge, Madison, Indiana, during the summers of 2002 and 2003. We used a nearest neighbor analysis for the spatial placement of the centroids of cerulean warbler territories. The analysis indicated that clustering occurred in three out of the five study plots. Territories which exhibited clustered distribution had significantly higher amounts of vegetative stratification, more trees, and trees with smaller diameter than territories which were not clustered.