Showing papers in "American Midland Naturalist in 2015"
TL;DR: The mowing of fields with Asclepias syriaca extended the monarchs' breeding season and increased overall monarch reproduction, however, timing of mowing was critical and must be determined empirically for different milkweed species and in different locations.
Abstract: To determine if manipulation of milkweed's natural phenology would increase monarch reproduction, strips were mowed in fields in upstate New York in early Jul., late Jul., and mid Aug., 2006, for comparison to an unmowed control. Common milkweed (Asclepias syriaca) was then monitored from Jul. 29 through Sep. 24 for plant height, vegetative stage, level of herbivory, condition, monarch eggs and larvae, and the position of eggs on leaves and stems. We found mowing on Jul. 1 and 24 spurred the regrowth of milkweed and sustained a more continuously suitable habitat for monarch oviposition and larval development than the control. Mowing on Aug. 17 proved too late for recovery of the milkweeds. Significantly more eggs were laid on the fresh resprouted milkweeds than on the older and taller control plants. In the strips mowed on Jul. 1, peak egg densities occurred in late Jul.; in the strips mowed in late Jul., peak egg densities occurred in early to mid Aug. Depending on the timing of mowing, the milkweed plant height, developmental stage, and condition differed. As predicted, the mowing of fields with Asclepias syriaca extended the monarchs' breeding season and increased overall monarch reproduction. However, timing of mowing was critical and must be determined empirically for different milkweed species and in different locations. This mitigation procedure could be fostered along roadsides, along edges of fields and pastures, in USDA conservation reserve program lands, and along power lines and other rights of way.
41 citations
TL;DR: The authors used historical archives and current forest inventory data from the past two centuries to quantify forest composition and structure following fundamental shifts in land use for a forest in the Fall Line Hills of Alabama (pre-European settlement (1820 and 1842), pre-industrial logging (1905), U.S. Forest Service acquisition (1943), and contemporary conditions (present)).
Abstract: Documenting changes in forest composition and structure through time and in response to disturbances strengthens our understanding of the processes that have created contemporary forest ecosystems. Results from these studies also provide the historical range of variation in forest characteristics, which is essential for establishing place-based targets for forest management. Using historical archives and current forest inventory data from the past two centuries, we quantified forest composition and structure following fundamental shifts in land use for a forest in the Fall Line Hills of Alabama (pre-European settlement (1820 and 1842), pre-industrial logging (1905), U.S. Forest Service acquisition (1943), and contemporary conditions (present)). To quantify conditions prior to European settlement, we analyzed General Land Office surveys of 1820 and 1842. We used Reed (1905) and Harper (1943) to document conditions during the early to mid-20th century. To quantify current forest conditions, we samp...
24 citations
TL;DR: In this article, radio transmitters were used to monitor massasaugas during a prescribed fire to assess direct and indirect effects of fire on the snakes' behavior, and the results of this study suggest ways to minimize impacts from prescribed fires on massasauga populations.
Abstract: The eastern massasauga rattlesnake (Sistrurus catenatus) is a threatened species that occurs in habitats frequently targeted by prescribed burns. There have been reports of massasauga mortality as a result of prescribed fires, but little is known regarding the indirect effects of fire on this species. The objective of this study was to monitor massasaugas during a prescribed fire to assess direct and indirect effects. We initially implanted radio transmitters in 13 massasaugas inhabiting an area targeted for periodic prescribed fires and tracked them following a prescribed fire to determine burn related-mortality and behavioral influences. Data loggers, temperature sensitive paint, and measuring posts were used to record detailed fire data. Of the five snakes on the burn unit at the time, two died as a result of the fire. No differences were observed in daily movements and home range sizes between burn categories (in the burn, same site not in the burn and at a nearby unburned site). Snakes on and off the burn unit at the same site exhibited the same habitat preference for wetland habitats, whereas snakes at the control site preferred herbaceous areas. Slight differences were observed in microhabitat selection related to litter depth, surface light intensity, distance to water, and surface temperature. The snakes did not appear to alter their seasonal activities as a result of the prescribed fire. The results of this study suggest ways to minimize impacts from prescribed fires on massasauga populations.
24 citations
TL;DR: The findings suggest selective foraging may be more common among generalist predators than previously considered, and it is proposed striped and unstriped morphs may represent a trophic polymorphism in P. cinereus.
Abstract: Numerous authors have studied the diet of the Eastern Red-backed Salamander (Plethodon cinereus) and have described this species as a generalist predator of invertebrates. In most studies, prey taxa are identified to the family or order level. Additionally, few studies have directly assessed dietary preference by comparing diet to available prey. We chose an important component of the diet of red-backed salamanders (ants) to test whether salamanders altered their diets temporally and to determine if salamanders preyed on a subset of available ant prey. We identified ant species in salamander diets over a 13 mo period. In the fall season we also compared ants in stomach contents to those available in the surrounding leaf litter to determine if territorial residents of P. cinereus selectively forage on different ant species. We found significant temporal differences in ant species incorporated in the diet of P. cinereus that were consistent with our detailed examination of salamander ant preference...
24 citations
TL;DR: In this article, the authors used a 3 x 2 factorial design (L. maackii present/absent/removed and O. virginianus present/excluded) to assess individual and interactive effects of these species on survival of sugar maple seedlings in a deciduous forest in southwestern Ohio.
Abstract: Invasion by Amur honeysuckle (Lonicera maackii) and browsing by white-tailed deer (Odocoileus virginianus) in eastern deciduous forests negatively affect diversity and abundance of herbaceous vegetation and tree seedlings. We used a 3 x 2 factorial design (L. maackii present/absent/removed and O. virginianus present/excluded) to assess individual and interactive effects of these species on survival of sugar maple (Acer saccharum) seedlings in a deciduous forest in southwestern Ohio. Survival of seedlings was negatively affected by presence of honeysuckle and browsing by deer, but there was no significant deer x honeysuckle interaction. Negative effects on survival and, hence abundance, of sugar maple seedlings could affect the relative dominance of species of canopy trees in these forests. Because there was no honeysuckle x deer interaction, control measures that target Amur honeysuckle and white-tailed deer separately could be employed without producing unintended effects on sugar maple seedlings.
20 citations
TL;DR: In this paper, the effect of fire intensity and pre-fire vegetation on soil biogeochemistry in Florida scrubby flatwoods was investigated, and the results showed that all nutrients and N mineralization rates significantly increased after fire.
Abstract: Fire is a major factor in the ecosystem dynamics of upland Florida habitats. Fire impacts have been well studied in terms of plant community responses, but the effects of fire on soil characteristics and post-fire plant-microbial interactions in these systems remain poorly documented. We investigated the effect of fire intensity and pre-fire vegetation on soil biogeochemistry in Florida scrubby flatwoods. We measured vegetation structure in 30 plots of ¼ m radius before a prescribed burn. Fire duration and temperatures were recorded in each plot. Soil samples taken immediately preceding and 2 w after the burn were analyzed for organic matter, inorganic N, available P and K, N mineralization rates, and potential nitrification rates. All nutrients and N mineralization rates significantly increased after fire. N and P increases were positively correlated with both fire intensity and vegetation. N mineralization was most strongly correlated with changes in available soil P, suggesting P stimulated N ...
19 citations
TL;DR: This paper examined orientation strategies of crayfish collected from lake and river habitats to an odor source dispersed in either a lotic (river) or a lentic (lake) manner.
Abstract: Crayfish of the species Orconectes virilis inhabit two distinct types of hydrodynamic environments: lakes and rivers. Odor cues in these habitats convey chemical information differently due to dispersion by different physical processes. In the laboratory we examined orientation strategies of crayfish collected from lake and river habitats to an odor source dispersed in either a lotic (river) or lentic (lake) manner. Our results showed lake crayfish had variable responses under both flow regimes whereas river crayfish oriented similarly under both flow regimes. Lake crayfish increased walking speeds, decreased heading angles, and decreased turn angles while orienting under lotic versus lentic conditions. Conversely, river crayfish oriented similarly under both flow regimes and reflected lake crayfish behavior in lotic flow. We conclude lake and river crayfish show differences in their orientation strategies due to influences from sensory signals in their source habitat. These results show crayfish...
17 citations
TL;DR: The potential preference for natural crevice/cavity roosts by little brown bats may have been a pre- adaptation that allowed the species to take advantage of the rapidly growing availability ofcrevice/Cavity mimicking anthropogenic roosting during the spread of Europeans throughout North America.
Abstract: In recent decades tree roosts of endangered Indiana bats (Myotis sodalis) have been more heavily studied than those of little brown bats (Myotis lucifugus), a much more common sympatric bat species. Motivated by precipitous declines in both species’ populations, we attempted to address this inconsistency by comparing the characteristics of these sibling species’ roosts. We used radio telemetry to find roosts of adult female bats of both species in two sites in southern Illinois and two sites in south-central Indiana. We then collected data on roost characteristics and bat movements. Little brown bats used more anthropogenic roosts and crevice/cavity roosts than Indiana bats, which used exfoliating bark roosts almost exclusively. Additionally, both species roosted in similar tree genera with similar DBHs (diameter at breast height) and roost heights. However, little brown bats roosted in shorter trees and in bigger clusters (based on emergence counts) than Indiana bats. Both species moved similar ...
17 citations
TL;DR: This paper used 21 y of data from the Manitoba metapopulation to assess effects of weather and land management on the western prairie fringed-orchid population in Canada and the United States.
Abstract: The western prairie fringed-orchid is a rare North American orchid restricted to a few remnants of wet to mesic tallgrass prairie. It is federally listed in both Canada and the United States and both countries have developed a recovery plan for the species. Two key management objectives are to monitor population trends and identify beneficial management practices. We used 21 y of data from the Manitoba metapopulation to assess effects of weather and land management on this species. Our results suggest the metapopulation in Manitoba is relatively stable. Western prairie fringed-orchids appear to benefit most from a combination of warm temperatures in the previous growing season followed by cool snowy but short winters and wet springs. Periodic burning (e.g., every 2–3 y) may benefit fringed-orchids, whereas grazing may be detrimental. This was not a controlled experiment, however, and gaps in the data may have influenced our results. Prescribed burning is a viable management tool for curtailing wo...
15 citations
TL;DR: Reduced throughfall and soil moisture below shrubs supported the hypothesis that L. maackii competes with tree seedlings by interception and were inconclusive regarding the hypothesis of competition by water uptake.
Abstract: We quantified the fine root length density of Lonicera maackii (Amur honeysuckle) and native trees at two depths on transects away from individuals of this invasive shrub and tested whether the invasive shrub L. maackii reduced water availability for other forest plants by either of two mechanisms: (1) intercepting rainwater during light rain events or (2) absorbing large amounts of water through its fine roots. To test the two hypothesized mechanisms, we selected plots near large L. maackii shrubs and control plots away from any large L. maackii shrubs in the forest understory. Within each plot we placed a trenched and an untrenched subplot and measured soil water content in each. We also measured precipitation above and below L. maackii canopies. We found that within 2 m of large L. maackii shrubs, this shrub accounted for a large fraction (22–25%) of the fine roots in the top 12 cm of soil. Reduced throughfall and soil moisture below shrubs supported the hypothesis that L. maackii competes wit...
15 citations
TL;DR: This is the first time a population of an ericaceous species has been shown to be pollinated primarily by nocturnal floral visitors and suggests pollination biologists should not be so quick to discount these potentially important pollinators.
Abstract: Studies of pollination biology are largely diurnally biased, especially in plant species whose flowers conform to diurnal pollination syndromes. Though these syndromes can be useful in generating hypotheses regarding a species’ primary pollinators, they may also lead to incorrect assumptions. This study explores the relative contributions of diurnal and nocturnal pollination to fruit set in Lyonia lucida, an ericaceous shrub of the southeastern United States whose floral form suggests pollination by bumble bees. Floral visitation to L. lucida and pollen loads of visitors were quantified in a population of the species in Central Florida (U.S.A.), and the relative contributions of diurnal and nocturnal pollination tested. Mating system characteristics of L. lucida were also examined. Results show L. lucida flowers are visited mainly by nocturnal moths, who are capable of carrying large pollen loads, and nocturnal pollination is the primary driver of fruit set. In addition L. lucida at the study sit...
TL;DR: It is inferred that diet is not a likely driver of disparate subpopulation growth rates of this recovering species, and the first rigorous analysis of bobcat diet in Ohio is presented.
Abstract: Bobcats (Lynx rufus) are a native carnivore of Ohio, but by 1850 were extirpated or nearly so following pioneer settlement of the state. The first modern record of a bobcat in Ohio was an adult male killed in 1946. Distribution accounts indicate that population re- establishment began around 2000. Today the bobcat is protected, and verified sightings, camera surveys, and genetic analyses point to two subpopulations: a fast growing, self-sustaining eastern subpopulation, and a more slowly growing southern subpopulation. We evaluated stomach contents of 120 adult and subadult bobcat carcasses to help understand the disparity in subpopulation growth rates, and inform proper bobcat management. We identified prey species morphologically. We quantified prey species taken and converted their frequencies to caloric intake estimates. We calculated dry weight estimates of prey groups and compared them between bobcat age classes, sexes, regions, and across seasons. We examined regional diet differences furt...
TL;DR: The results suggest both sexes participate in territorial defense through physical confrontations and such encounters can be costly to both dispersing juveniles and resident adults.
Abstract: Conspecific aggression may play an important role in partitioning resources and maintaining territories among beavers (Castor canadensis), yet few studies have examined physical evidence of agonistic encounters. We trapped and examined pelts from 147 beavers harvested between 2006 and 2012 from the Sangamon River (n = 96) and tributary streams (n = 51) in central Illinois. We modeled the influence of sex, age class, season (predispersal or dispersal), and habitat (river or tributary stream) on the number of recent injuries caused by conspecifics. One-third (51/147) of beavers had ≥1 injury; of those, the median number of injuries was 2.0. Kits had fewer injuries than adults (βKit = −2.24 ± 0.63), but yearlings and subadults did not (βyearling = 0.02 ± 0.38, βsubadult = −0.22 ± 0.48). Beavers on small streams had only one-quarter of the injuries recorded for beavers on the river (βStream = −1.34 ± 0.82). We failed to detect differences in injuries between the sexes. Our results suggest...
TL;DR: Results suggest decreasing fire frequency to once every 2 y, perhaps combined with biennial grazing management, may enhance fire behavior to better meet management objectives.
Abstract: Fire and grazing are commonly used to manage nonnative grasses in the Northern Great Plains, but the effects of fire frequency and management between fire events on fire behavior in this region are poorly understood. We examined temperature and duration of prescribed spring fires at two locations where plots were treated with two fire frequencies (annual or biennial), simulated grazing (1 mo of weekly clipping in spring) and no simulated grazing. In May 2011 and 2013, soil surface fire temperatures and heat duration were monitored in treatment plots using thermocouples. Probes also were placed at 1, 2, and 3 cm depths to measure soil heat transfer. Lethal heat duration (>60 C) at the surface tended to be longer in plots treated with biennial fires compared to plots treated with annual fires. Fires in 2011 had higher maximum temperatures than 2013. Cooler fires in 2013 were characterized by longer durations of lethal heat. However, simulated grazing increased residence time of lethal temperatures ...
TL;DR: The vegetative reproduction and dynamics of Andropogon gerardii, a dominant C4 perennial grass of the Great Plains of North America, were compared between tallgrass and northern mixedgrass prairie habitats and similar population growth rates occurred in both habitats.
Abstract: Plant species with wide distributions may differ in their population dynamics across their range, especially in contrasting habitats. Most tiller recruitment of perennial grasses occurs vegetatively from the belowground bud bank rather than from seed. Seed reproduction often occurs under a narrower range of environmental conditions than vegetative reproduction. As a result flowering and seedling recruitment patterns of a species often differ between contrasting habitats and across its range. How vegetative reproduction and bud bank dynamics of a species vary between contrasting habitats has not been well studied and could explain the differences in its persistence and productivity between habitats. Therefore, the vegetative reproduction and dynamics of Andropogon gerardii, a dominant C4 perennial grass of the Great Plains of North America, were compared between tallgrass and northern mixedgrass prairie habitats. Bud production and tiller recruitment in 10 populations were examined throughout an a...
TL;DR: Increased distribution of mottled sculpin in previously unavailable upstream habitats coupled with substantial post-restoration movement distances provides new insight on their potential for redistribution following habitat reconnection, which is an important consideration for stream restoration projects.
Abstract: Anthropogenic activities have greatly altered the natural flow regime of lotic ecosystems in many ways, including dams and culverts, which restrict sediment transport and fragment fish habitat. Sculpins, Cottus spp., are an important food-web link between macroinvertebrates and larger stream fishes and are greatly affected by culverts. Results from a previous study indicate a substantial increase in the relative abundance of mottled sculpin, Cottus bairdii, was observed upstream of a renovated road-stream crossing during the first season after construction. Redistribution of this nature from a putatively sedentary species would have required substantial movement. Our objectives were to quantify post-restoration mottled sculpin movement and habitat use in a restored stream reach. The extent of post-restoration mottled sculpin movement and habitat use were directly measured using telemetry of Passive Integrated Transponder (PIT) tag-marked fish. The maximum linear distance moved by a marked mottled...
TL;DR: There were significant differences in the percentage of prey consumed by otters at Emiquon and in previous studies conducted in Whiteside County, Illinois, and Alberta, Canada.
Abstract: North American river otters (Lontra canadensis) frequently visit latrines where they deposit urine, feces, and anal secretions as olfactory signals. River otter scat was collected from latrines to identify prey at the Emiquon Preserve and the Emiquon National Wildlife Refuge located along the Illinois River near Havana and Lewistown in Fulton County, Illinois. Remains of prey from dissected scats were compared to osteological resources to taxonomically identify the remains. Fish were present in 85.4% of the dissected samples. Common carp (Cyprinus carpio) were the most common fish preyed upon during the study, occurring in 69.8% of all dissected samples. Crayfish were present in 77.1% of samples. Amphibians, insects, filamentous algae, green-winged teal (Anas crecca) or blue-winged teal (A. discors), and muskrat (Ondatra zibethicus) were also consumed. The minimum number of individuals (MNI) consumed was also determined based on the prey remains present. The results of a two-tailed Fisher's exact...
TL;DR: Examination of herbaceous vertical vegetation structure and diversity in plants, arthropods, and arbuscular mycorrhizal fungi in three Great Lakes sand dune chronosequences found vertical structure of vegetation can be important in explaining richness and abundance in other trophic levels across a successional gradient.
Abstract: While ecologists have studied succession for well over 100 y, there has been little characterization of diversity patterns in nonplant organisms or their interactions across successional gradients. In this study we examined herbaceous vertical vegetation structure and diversity in plants, arthropods, and arbuscular mycorrhizal fungi (AMF) in three Great Lakes sand dune chronosequences. Plant species richness increased linearly across the primary successional gradients at the three sampling sites, while plant vertical structure remained constant. Total arthropod abundance and species richness were positively associated with plant vertical cover, while AMF spore abundance and morpho-type richness were positively associated with plant species richness. Carnivore and herbivore functional groups of arthropods responded differently to plant vertical cover and species richness. Diversity across early primary successional gradients does not consistently increase among different trophic levels, and the ve...
TL;DR: Results suggest mammalian herbivores have an important functional role in prairie communities with potential consequences for community dynamics and the success of prairie restorations.
Abstract: Historic, wide-spread destruction of native prairies in Minnesota was caused by conversion to agricultural land, disruption of disturbance regimes, and loss of key species. Attempts to restore tall-grass prairies have resulted in a new ecosystem type on the Midwestern landscape, with novel assemblages of both plant and animal species. The mammalian herbivore community, once dominated by bison, is now primarily comprised of white-tailed deer (Odocoileus virginianus), Eastern cottontail rabbits (Sylvilagus floridanus), and small mammals such as meadow voles (Microtus pennsylvanicus). The role of this assemblage of herbivores in restored prairies is not well understood. This study characterizes patterns of mammalian herbivory on five legume species in restored prairie in southern Minnesota. Legumes were sampled along transects that varied in their distance from the prairie-forest boundary and time since prescribed burning. Herbivore selectivity was determined for each legume species using an electiv...
TL;DR: In this article, the authors sampled soil, vegetation, and amphibians in 21 vernal pools in Pictured Rocks National Lakeshore (PIRO) during spring 2010 to provide quantitative and qualitative evaluation of the abiotic and biotic characteristics of these pools to help managers determine which pools to prioritize for conservation.
Abstract: Vernal pools are isolated ephemeral bodies of water that are often overlooked on the landscape. Despite their temporary nature, these pools are important to forest communities, providing critical breeding habitat for amphibians and an important food and water source for other taxonomic groups including birds, bats, and other terrestrial vertebrates. Sparse information about vernal pools in the upper Midwest, including Pictured Rocks National Lakeshore (PIRO), inhibits conservation. We sampled soil, vegetation, and amphibians in 21 vernal pools in PIRO during spring 2010 to provide quantitative and qualitative evaluation of vernal pool abiotic and biotic characteristics within PIRO to help managers determine which pools to prioritize for conservation. Average vernal pool size sampled was 0.124 ha. Soils had an average of 13.5% carbon and 0.7% nitrogen. Vegetation was diverse within the vernal pools, with 115 vascular plants identified. Five species of amphibians were encountered during our surveys...
TL;DR: In this article, the authors observed abnormally long parturition seasons in free-ranging elk populations in Missouri and South Dakota during 2012, where the last known births occurred on 26 Sep. 2012 in South Dakota and 4 Sep. 2013 in Missouri.
Abstract: The timing of births in ungulates has significant implications for juvenile survival and population growth. For North American elk (Cervus elaphus), typical parturition season ranges from late May to early Jun., and juveniles born outside of this peak characteristically exhibit lowered survival. We observed abnormally long parturition seasons in free-ranging elk populations in Missouri and South Dakota during 2012. Both populations exhibited late births; the last known births occurred on 26 Sep. in Missouri and 4 Sep. in South Dakota. Duration of parturition season was 112 and 119 d in Missouri and South Dakota, respectively. In Missouri, late births likely resulted from breeding by both yearling females and males. Late parturition in South Dakota may be caused by extended estrous cycles of elk that occurred on high quality range where few adult males were located.
TL;DR: In this paper, the effects of biomass harvest on nest success and density using 109 blue-winged teal, mallard, and ring-necked pheasant nests found in southwestern Minnesota during 2009 (pretreatment) and 2010 (posttreatment).
Abstract: Grasslands enrolled in conservation programs provide important habitat for nesting game birds and waterfowl, but conservation grasslands have been targeted as a source of biomass for bioenergy and this could impact nesting birds. We studied the effects of biomass harvest on nest success and density using 109 blue-winged teal (Anas discors), mallard (Anas platyrhynchos), and ring-necked pheasant (Phasianus colchicus) nests found in southwestern Minnesota during 2009 (pretreatment) and 2010 (posttreatment). Grassland biomass was harvested in late autumn of 2009 with production-scale machinery. Harvest treatments included controls (0% biomass removal), partial harvest (50 or 75% biomass removal), and full harvest (100% biomass removal) from 8 ha plots. Nest success averaged 31% and was not influenced by biomass harvest. Daily survival rates were greater for nests located closer to wetlands. Estimated total nest density (0.42 nests ha−1; corrected for survivorship) was similar across harvest treatmen...
TL;DR: Monitoring herbaceous-layer plant species presence and cover in two peri-urban nature preserves in central Indiana shows considerable turnover in individual species presence, with perennial forb species the most likely species to be found in only 1 y or the other.
Abstract: Peri-urban natural areas, at the boundaries of cities and adjacent agricultural/ rural land, are subject to ecological threats endemic to both land use types. We used permanent plots to document changes in habitat quality by monitoring herbaceous-layer plant species presence and cover over a decade (1996/97 and 2007) in two peri-urban nature preserves in central Indiana, U.S.A. The preserves are comprised of different forest community types: wet-mesic depressional forest and mesic upland forest. Habitat characteristics, based on Floristic Quality Assessment parameters, showed only a single change for either preserve between survey years: wetness values were lower in the wet-mesic depressional site in 2007 than in 1996, indicating more plants with affinity for wet soil. No changes in community structure (total species richness, evenness, and diversity) were found. The number of nonnative species increased between survey years, especially in the wet-mesic depressional forest, where numbers went from zero to six, five of which are classified as invasive. There was considerable turnover in individual species presence, with perennial forb species the most likely species to be found in only 1 y or the other. Species did not rearrange themselves within plots, but completely appeared or disappeared from all plots within a preserve between the sample years, suggesting that species composition of the flora is dynamic. Management recommendations, including those related to evidence of heavy deer browse, are presented based on our findings. Repeat monitoring of our plots in future decades will allow quantification of any extinction debt that may now be in place due to the increased presence of nonnative species, especially invasive shrubs escaped from landscaping.
TL;DR: It is predicted the diel emission patterns of floral scent might covary with the daily abundance of diurnal moths, identified in a previous study as the most important pollinators in a Konza Prairie population of P. divaricata, and peaks in median floral scent emissions are documented, coinciding with peaks in moth visitation and resulting seed production.
Abstract: The study of floral traits and pollination for the plant genus Phlox has historically been focused on either surveys of general pollinator affinities across the genus or detailed research on pollinator-mediated evolution of floral color in a single species (Phlox drummondii). The purpose of this study was to explore a different kind of trait - floral scent - in Phlox divaricata, a species noted for its strong scent. Specifically, we predicted the diel emission patterns of floral scent might covary with the daily abundance of diurnal moths, identified in a previous study as the most important pollinators in a Konza Prairie population of P. divaricata. Consistent with this prediction, we documented peaks in median floral scent emissions at 1000-1200 and 1930-2130, coinciding with peaks in moth visitation and resulting seed production. Two groups of scent compounds contributed to this pattern; linalool and its associated lilac aldehyde/alcohol compounds (especially lilac aldehyde B) contributed a greater proportion to scent at 1000-1200, while aromatic compounds (including benzaldehyde and benzyl acetate) contributed a greater proportion to scent at 1930-2130 and other afternoon time periods. These volatiles are known floral attractants for several lepidopteran pollinators, including noctuid moths. However, there is an additional peak in pollinator abundance (Hemaris diurnal hawkmoths) and seed set at a time when scent production is relatively low (1400-1600) suggesting additional factors mediate both pollinator behavior and floral volatile emissions. Future studies of P. divaricata should test for the presence of destructive floral enemies that might be attracted by floral volatiles during mid-afternoon periods, as well as the importance of visual floral traits (color, shape) in attracting diurnal moths, an important functional group of pollinators that has received minimal attention in North America.
TL;DR: The results suggest Trirhabda beetles may negatively impact Eurosta demographics and highlight the need for further study on how factors affecting gall induction may influence the structure of insect communities.
Abstract: Phytophagous insects from different feeding guilds may compete indirectly via altering the chemical defenses or nutritional quality of their shared host plants. Gall-formers are understudied in this context but may be susceptible to this mode of competition early in their life history, when they may be particularly sensitive to changes to the specific reactive tissue needed for gall development. Here, we conducted a natural experiment to investigate the effect of folivory of Canada goldenrod, Solidago altissima, by Trirhabda beetles on gall induction success for the goldenrod gall fly, Eurosta solidaginis. We monitored oviposition events and gall development on individual Solidago ramets at sites differing in their levels of Trirhabda folivory. We found a strong inverse relationship between Trirhabda leaf damage and successful gall induction rates. These results suggest Trirhabda beetles may negatively impact Eurosta demographics and highlight the need for further study on how factors affecting g...
TL;DR: Ingestion of microcystin may represent a previously unrecognized stressor on bat populations in this region and is measured in emergent Hexagenia limbata mayflies and fecal samples collected from a maternity colony of little brown bats located adjacent to a Michigan lake.
Abstract: Recent studies documented the potential transfer of microcystin, a hepatotoxin produced by some cyanobacteria, from aquatic to terrestrial ecosystems. Using enzyme linked immunosorbent assay, we measured microcystins in emergent Hexagenia limbata mayflies and fecal samples collected from a maternity colony of little brown bats (Myotis lucifugus) located adjacent to a Michigan (U.S.A.) lake that experiences seasonal blooms of toxicogenic Microcystis aeruginosa. All H. limbata and M. lucifugus fecal samples contained microcystin (H. limbata: mean = 293.88 ng/g dw ± 35.99 se, n = 39; M. lucifugus: mean = 262.10 ng/g dw ± 31.08 se, n = 20). Ingestion of this toxin may represent a previously unrecognized stressor on bat populations in this region.
TL;DR: For example, this article found that during the breeding season, male white-tailed deer (Odocoileus virginianus) take excursions outside of their normal home ranges, likely in search of receptive females.
Abstract: During the breeding season, male white-tailed deer (Odocoileus virginianus)have been reported to take excursions outside of their normal home ranges, likely in search of receptive females. However, we documented additional excursive movements by males during spring in north central Pennsylvania. From December 2011 – April 2012, we equipped 13 mature (≥2.5 y old) male white-tailed deer with global positioning system (GPS) collars programmed to record locations hourly. We defined an excursion as any occasion where a male traveled ≥1.6 km outside of its 95% home range boundaries for ≥12 h. Between 6 April and 6 June 2012, nine males (69.2%) made excursions with six making ≥2 excursions. Mean total path distance and duration of excursions was 4.0 km (range = 1.7-8.0 km) and 22 h (range = 12–40 h), respectively. Although the reason for spring excursions is obscure, hypotheses such as increased doe aggression before parturition, males returning to natal home ranges, or visitation to mineral sites d...
TL;DR: In this article, the authors evaluated the reproductive success of tree-nesting waterbirds on selected wetlands and rivers in northeast South Dakota during the 2008 and 2009 breeding seasons, and found that the success of these birds varied with the area of wetland habitat in the landscape.
Abstract: The northern Great Plains of North America provides critical breeding habitat for many colonial tree-nesting waterbirds, but reproductive success and population parameters for these species are largely unknown within the Prairie Pothole Region, specifically in South Dakota. The objective of this study was to evaluate reproductive success of colonial tree-nesting waterbirds on selected wetlands and rivers in northeast South Dakota. During the 2008 and 2009 breeding seasons, nesting and fledging success of Black-crowned Night-Heron (Nycticorax nycticorax), Great Blue Heron (Ardea herodias), Cattle Egret (Bubulcus ibis), Great Egret (A. alba), Snowy Egret (Egretta thula), and Double-crested Cormorant (Phalacrocorax auritus) were estimated in 39 individual colonies. A total of 2551 individual nests were monitored from 15 Apr. - 15 Aug. in 2008 and 2009. Overall apparent nest and fledge success (respectively) were: Black-crowned Night-Heron (52.1%, 47.9%), Great Blue Heron (58.2%, 35.9%), Cattle Egret (73.1%, 69.2%), Great Egret (61.5%, 50.7%), Snowy Egret (83.6%, 81.7%), and Double-crested Cormorant (70.4%, 54.2%). Nest abandonment accounted for an average of 47.6% of nest failures for all species combined. Nest structure failure and young dying within nests accounted for most failures to fledge. Nesting success increased with the area of wetland habitat in the landscape for all species analyzed. Lower reproductive success of Black-crowned Night-Heron and Great Blue Heron, compared to other findings across the U.S. and Canada, suggests that these breeding populations in northeast South Dakota may be declining. Cattle Egret, Great Egret, Snowy Egret, and Double-crested Cormorant reproductive success is relatively high in northeast South Dakota compared to other North American populations. Preserving and restoring wetland habitat surrounding waterbird colonies will provide successful nesting habitat as well as foraging areas and opportunities for new colony site locations.
TL;DR: A more spatially-targeted effort to reduce density, by removal of social groups, in areas where chronic wasting disease is present may provide better efficacy in reducing potential for disease transmission.
Abstract: We studied the seasonal home range of individual white-tailed deer (Odocoileus virginianus) as it related to landscape pattern (forest-edge density; the ratio of agriculture to forest), local deer density, and harvest intensity in a population managed for control of chronic wasting disease in south central Wisconsin. The ratio of agriculture to forest showed strong positive correlation to home range size for most age and sex classes, while forest edge density was inversely related to home range size for adult females. Individual home range size proved largely independent of density and harvest intensity. It is likely that socio-spatial factors (i.e., fidelity) and the availability of food and cover influence home range size more strongly than hunting pressures or density reductions. This suggests localized reductions may create areas of low density without changing the behavior patterns of the population. Our findings suggest a more spatially-targeted effort to reduce density, by removal of socia...
TL;DR: R. ficaria's ability to maintain production across a large range of litter depths may provide a competitive advantage over plant species not adapted to varying litter depths.
Abstract: Ranunculus ficaria is an invasive plant species in the northeastern United States, especially in urban riparian habitats. Changes in the frequency and intensity of flooding events in these urban riparian corridors create patches of heavy litter and patches of bare ground. Many plant species either cannot penetrate deep litter, or they are susceptible to freezing temperatures and drying conditions on bare ground. This can result in competitive advantages for invasive species that are adapted to these varying conditions. We conducted a field experiment to test the effects of leaf litter depth on R. ficaria biomass, bulbil production, flower production, and seed production under deep (20 cm) litter, intermediate (10 cm) litter, shallow (5 cm) litter, and bare ground along an urban stream in Louisville, Kentucky. Deep litter and lack of litter decreased plant biomass compared with shallow litter. Bulbil production was not significantly different across treatments. Flower and seed production were only...