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Sericea lespedeza (Lespedeza cuneata) is a high-tannin, late-season invasive forb species that reduces biodiversity in tallgrass prairie ecosystems. The largest tallgrass prairie remnant exists in the Flint Hills of Kansas and Oklahoma, where the most common grazing management practice involves prescribed fire in early spring followed by intensive stocking with yearling beef cattle from April to July. Sericea has continued to spread under this management regime. From 2013 to 2016, in Kansas Flint Hills tallgrass prairie, we tested the effects of using spring burning with early-season steer grazing, followed by late-season sheep grazing (Steer+Sheep) compared to spring burning followed by steer grazing only (Steer) on sericea vigor, grassland birds, and pollinators. Density and nest success of Grasshopper Sparrows (Ammodramus savannarum) and Eastern Meadowlarks (Sturnella magna) were not negatively affected by Steer+Sheep relative to Steer treatments, whereas there was evidence of a negative effect in these same metrics for Dickcissels (Spiza americana). Abundance of butterflies and their nectar sources were similar between treatments but abundance of grassland specialist butterfly species was low, overall. Comprehensively, Steer+Sheep effectively controls the spread of sericea but may not create habitat for all tallgrass prairie wildlife species.
Habitat features associated with nest locations can affect survival and reproductive success of individuals living at particular nest sites. In this study we analyzed vegetation associated with nests of prairie voles (Microtus ochrogaster), living in 0.1 ha outdoor enclosures, and found they differed from plants at randomly selected locations. Although vegetation changed during the 15 wk study, vegetation at nests tended to provide cover (taller plants) or impede predators (thornier plants). Vegetation close to nests as well as in the habitat patch (enclosure) where the nest was located predicted female survival, pup survival, and female reproductive success. The number of pups produced per nest was not related to vegetation near nests but increased with increasing thorny vegetation within enclosures. Pup survival was greater when there was more woody vegetation near nests and more dicots within enclosures. Female survival was negatively associated with plant height at nests and woody vegetation within enclosures but positively related to preferred food plants within enclosures. Our results suggest fitness consequences resulting from vegetation near nests and on a larger spatial scale surrounding the nest could influence nest site selection in prairie voles.
Black-tailed prairie dogs are herbivorous rodents known to have large effects on grassland landscapes in North America. They have considerable impacts on prairie plant communities as the result of repeated clipping of vegetation that can reduce preferred forage species and may indirectly result in increased abundance of disturbance-tolerant species. We investigated plant communities within three different habitat types: Active and inactive prairie dog colonies, and adjacent suitable, but unoccupied, control areas in the Northern Great Plains of Montana, U.S.A. Plant species richness did not vary markedly between the three habitat types. However, plant composition measured as cover of plant life forms (forbs, shrubs, and graminoids), which was further divided into native status (native or introduced), and plant species indicators (plant species associated with a specific habitat) did vary distinctly between the three habitat types. Differences in plant composition between the habitat types suggests black-tailed prairie dog activities result in greater diversity of plant microhabitats at a landscape scale, and prairie dogs are an important component of the overall ecosystem in the Northern Great Plains of North America.
The tallgrass prairie ecosystem was historically maintained through the interaction of climate, fire, and grazing by large ungulates. Efforts are being made to return large ungulates (bison) back into prairie landscapes, but successful introductions can be constrained by suitable habitat as determined by resource availability (plant biomass, forage quality of the plant biomass, and soil carbon and nitrogen), particularly given some of these tracts are former arable land that has been restored to tallgrass prairie. The objective of this study was to quantify whether plant biomass (available forage) differs between prairie types, if forage quality varies across native prairie remnants and restored prairies, and if these differences are related to carbon and nitrogen storage in soil. We sampled native prairie remnants, low seeded-diversity older restored prairies, and high seeded-diversity younger restored prairies at Nachusa Grasslands, Illinois during July 2014. Total plant biomass differed between the three prairie types, with the high seeded-diversity younger-restored prairies having almost twice that of the low seeded-diversity older-restored prairies and more than twice that of the remnant prairies. In regard to forage quality, the percentage of crude protein in dry matter was greater in the remnant prairies compared to both of the restored prairie types. The high seeded-diversity younger restored prairies had the highest lignin concentration in the forage. The fat content of forage was highest in the high seeded-diversity younger restored prairies. Total soil carbon and nitrogen did not differ between the three prairie types at either the 0–10 cm or 10–20 cm depth. The preliminary findings of this study suggest bison grazing within the introduction unit at Nachusa Grasslands will be more intensive within restored prairies as compared to remnants.
Mountain lions (Puma concolor) have many impacts on the ecosystems they inhabit, leading to both biological and social ramifications. Yet, due to the relatively recent natural recolonization by mountain lions of the Little Missouri Badlands Region of western North Dakota, detailed data regarding many aspects of this population have been lacking. We studied mountain lions occupying the Badlands Region to improve our understanding of the characteristics of the North Dakota mountain lion population. Our objectives included estimating annual survival rates, documenting sources of mortality in this population, and creating a population model using statistical population reconstruction (SPR) techniques. Between 2012 and 2016, the average annual survival rate estimated from known fate models was 0.456. Sex-specific annual survival was estimated at 0.589 for females and 0.259 for males. We recorded 17 cause-specific mortalities of marked mountain lions over the same 5 y period, plus the probable failures of two litters of marked dependent kittens. Results from our population model indicate annual population abundance estimates between 2005 and 2017 ranged from a low of 27 total mountain lions in 2005–2006 to a high of 165 in 2011–2012. The model indicated an increasing trend in total abundance between 2005 and 2012, then a reversal and sharp drop in abundance from 2012 to 2014, until the trend leveled with similar total abundances from 2014 to 2017. The results from our study can help inform current and future management decisions in North Dakota and may also provide insight for managers faced with potential mountain lion recolonization further eastward in the United States.
Bats exploit forest resources based on species-specific adaptations, resulting in differences in activity across forested landscapes. Forest management practices alter forests, impacting species differently and presumably affecting bat activity. Application of forest management that promotes species-specific bat conservation requires further understanding of bat response to silvicultural practices. We surveyed timber harvest treatments on two Indiana State Forests to compare bat activity across forest management treatments, in forests adjacent to harvests, and at locations across the harvest-forest gradient from May to July in 2013 and 2014. We used Wildlife Acoustics Song Meter SM2BAT+ detectors and Kaleidoscope Pro analysis software to survey bats in relation to four treatment types: clear cut, patch cut, shelterwood preparatory cut, and intact forest. Detectors were deployed at two points within each treatment and three points on the forested periphery of treatments and recorded for three consecutive nights. We examined bat activity using N-mixture models that estimate abundance and probability of detection for an open population and used Akaike's Information Criterion to select the best models. Based on identification of acoustic calls, eastern red bats and hoary bats were more active in harvest treatments than control treatments. Big brown, eastern red, and tri-colored bats were most active at harvest edges. Northern long-eared and Indiana/little brown bats were most active at harvest edges and in adjacent forest and hoary bats were most active at harvest centers. Differences in bat activity across these managed forests suggest bat assemblages benefit from management that employs an array of silvicultural methods, provides edge habitat, and maintains adjacent forest stands. Our results can be used to predict effects of forest management practices on species-specific bat activity to maximize bat usage of forests.
Our understanding of mammalian predation on salamanders is primarily restricted to small carnivorous species (i.e., shrews). We conducted a series of investigations to determine whether the Virginia opossum (Didelphis virginiana) is a predator of various salamander species [Desmognathus fuscus, Plethodon dorsalis, and Notophthalmus viridescens (adult and eft)] from the eastern United States. All species, including toxic newt efts, were palatable to opossums. These results suggest opossums could be an active predator of salamanders. In a second study, each terrestrial salamander species exhibited avoidance responses to kairomones from opossums indicating that despite a significant risk of mortality each salamander has evolved mechanisms to minimize predation risk. Combined with overlapping habitat preferences, foraging behavior that places them in contact, and a dietary preference for animal matter, these data suggest opossums may be an important predator on terrestrial salamanders.
The round goby (Neogobius melanostomus) was discovered in 2013 in the French Creek (Allegheny River Drainage) watershed and is the first documented invasion outside of the Lake Erie basin in Pennsylvania. The round goby throughout the Laurentian Great Lakes is known to eat dressenid mussels (Dreissenidae), but consumption of either dressenids or native mussels (Unionidae) in tributaries to Lake Erie is minimal based on low populations of any bivalves. The French Creek watershed, on the other hand, harbors 29 species of native freshwater mussels as well as introduced fingernail clams (Sphaeriidae; Corbicula fluminea). The objectives of this study were to document the diet of round gobies in the French Creek watershed to determine whether consumption of native freshwater mussels was occurring. Round gobies were collected in the summer months (May–Sept.) of 2016 via kick seine in four locations, dissected, and their stomach contents identified to lowest possible taxa. We separated the gobies into categories based on length classes, in order to determine if diet changed with increased size and age. Unionid mussels were consumed by all length classes, particularly in length class one (30–44 mm), but diet shifted to a dominance of sphaeriids in length class four (≥75 mm). Round gobies also consumed benthic aquatic insects, a large percentage of which were chironomids (greater than 24% in all size classes). This is the first documentation of unionid consumption by the round goby in Pennsylvania that poses possible threats to native mussels in the French Creek watershed.
Determining the genetic diversity of unionid populations is important for the preservation of the species and ecosystems in which they reside. The Yellow lampmussel, Lampsilis cariosa, is an endangered unionid found along the Atlantic Slope drainages in the United States and Canada. Along with many other North American unionid species, L. cariosa populations are declining. In order to enhance conservation efforts, the genetic structure and diversity of current populations must be examined. A sample of 178 individuals of L. cariosa from 20 populations in the Susquehanna and Delaware River drainages, and two different river populations in Maine were genotyped at the mitochondrial cytochrome oxidase subunit one (COI) gene and seven microsatellite loci. Haplotype genetic diversity for L. cariosa was low, while nucleotide diversity was high. Analysis of mtDNA showed significant population structure but lower than that of other mussel species. Our results indicate past gene flow among populations found in the Susquehanna and Delaware drainages with recent demographic expansion. As an endangered species with currently small population sizes, conservation efforts for L. cariosa should focus on protecting genetic diversity by preserving the largest populations in different drainages.
Intraguild predation and cannibalism are important behaviors that provide resources and influence interactions between different predators. Cannibalistic species should have a mechanism to identify offspring and suppress predation. We tested this hypothesis using two nonnative species of pholcid spiders in Ohio, Pholcus phalangioides and Pholcus manueli. In the laboratory we allowed females of both species to produce clutches. Once hatched the spiderlings were separated from their mother for 1 h and then reintroduced to the mother, a conspecific, or were introduced to an heterospecific adult female. The proportion of prey items consumed was recorded. Pholcus phalangioides predation patterns were consistent across species, but P. manueli feed on P. phalangioides young at twice the rate of young conspecifics, treating heterospecific young similar to control crickets. Further, mothers did not prey on their own young. These results highlight an important biological difference between the two species and indicate that intraguild predation may play an important role in interactions between the two species.
In the United States earthworms of two Asian species (Amynthas tokioensis and A. agrestis) are leading a northward invasion into temperate forests and horticultural landscapes. Some studies have shown temperature sensitivity in earthworms, but none has explicitly tested the range of heat tolerance for A. tokioensis and A. agrestis cocoons. This study tested the hypothesis A. tokioensis and A. agrestis cocoons would become nonviable when exposed to 55 C in a laboratory setting. Clitellate earthworms of A. tokioensis and A. agrestis were established in replicate incubation cultures to quantify cocoon production rate and to obtain cocoons of known source. Cocoons were then exposed to heat treatments (3 or 15 d at 20, 30, 40, 45, 50, 55, or 60 C) to determine viability after heat exposure. Twelve A. tokioensis and A. agrestis earthworms produced as many as 74 and 82 cocoons in 20 d, respectively (overall mean = 0.14 ± 0.10 cocoons earthworm–1 d–1). All heat treatments ≥40 C resulted in zero viability (P < 0.001), but the 30 C treatment was no different than the control at 20 C (P = 1.000). These findings were consistent regardless of species, treatment length, or period of incubation during which the cocoons were collected. The threshold of tolerance was between 27.1 C (maximum of the 30 C treatment) and 38.1 C (minimum of the 40 C treatment) for A. tokioensis and A. agrestis cocoons. These data may guide management decisions concerning the spread of A. tokioensis and A. agrestis to new locations.
Freshwater sponges (Porifera: Spongillida) are an understudied fauna. Many U.S. state and federal conservation agencies lack fundamental information such as species lists and distribution data. Such information is necessary for management of aquatic resources and maintaining biotic diversity. During the months of June, July, and August of 2013, 2014 and 2015 a survey was conducted in Tennessee to document species of freshwater sponges and obtain preliminary distribution data. Selected rivers and streams were sampled at two to five sites. A total of 520 sponge samples were collected. Spicules and gemmules were viewed and photographed using Scanning Electron Microscopy. Thirteen or 39% of the known species of freshwater sponges occurring in the North America have been collected from Tennessee's rivers and streams. Eunapius fragilis, Spongilla lacustris, and Trochospongilla horrida were the most abundant and widely distributed species. Corvospongilla becki and Heteromeyenia latitenta were the least frequently encountered sponges.
Large areas of the Northern Great Plains of North America were intentionally planted with the non-native crested wheatgrass 80–90 y ago. Land managers hope to restore these near-monoculture fields to more diverse native grassland. Our goal was to help guide selection of native species for restoration. We sampled vegetation at each of 24 fields planted with crested wheatgrass in the 1930's in northeast Montana across a range of soil textures. We documented composition at the edge of each crested field and in adjacent native vegetation, allowing us to rank native species as to their ability to persist with crested wheatgrass and determine how soil texture influences their ability to coexist with crested wheatgrass. We identified 29 native species that commonly re-established in crested wheatgrass fields. Sagebrush and several grasses occurred with similar abundance across all soils. Six forb species occurred preferentially on either heavy or light soils. Our results can be used to design seed mixes that will provide native species capable of coexisting with crested wheatgrass in eastern Montana. Application of our methods may be useful in other areas of the Great Plains.
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