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Eight eastern U.S. prairie sites were sampled for exotic species abundance in relation to levels of native diversity; including species and functional richness, species evenness, and functional group similarity for the alpha (quadrat; 1m2; n = 508) and gamma (site; n = 8) scales. Spearman's rank co- efficient analyses found only a weak negative correlation (P < 0.001; rs =–0.14) with species richness and exotic abundance; and was nonsignificant for the other measures of diversity. Principal Components Analysis (PCA) indicated instead that exotic abundance was more correlated with higher soil parameter values among the sites. Both Lonicera japonica and Lespedeza cuneata represented 90% of the exotic cover from among the study sites.
Arbuscular mycorrhizae (AM) are widespread in plant communities and are important mediators of plant community structure. However, patterns of variation among species and linkages with above-ground traits have received much less attention. To address this research need, we surveyed plant species from a long-term study of old field succession for AM colonization. Root tissue was collected from five individuals for each of 46 species that represented a range of origins and life forms. Root samples were cleared, stained, and examined to determine the percentage of colonized hyphae area and the number of vesicles and arbuscules. Nonnative species had greater hyphal colonization than native taxa, and the number of vesicles produced in woody species was lower than in the herbaceous species of the system. AM were associated with above-ground traits in both woody and herbaceous taxa, suggesting mycorrhizae integrate with other plant traits to generate resource acquisition strategies. AM decreased as species peaked later in succession for herbaceous species but was not associated in woody species. These results suggest AM may play an important role in species invasion and overall plant functional strategies, but these relationships may vary based on plant life form.
Milkweeds (Asclepias spp.) are host plants for monarch butterflies (Danaus plexippus), which are currently being considered for listing under the Endangered Species Act. Previous research has documented declines in milkweed availability in the Midwest, but less research has focused on the southern Great Plains. Furthermore, the influence of management practices on the structure of milkweed populations has not been evaluated. We assess the age structure of Asclepias viridis, an important milkweed species for monarchs in the southern Great Plains, in two land uses that differ in the frequency and timing of mowing. Plant age may influence resource availability for larval and adult monarchs by affecting foliar biomass and flower production, and flower production and subsequent seed production may influence the recruitment of new individuals to the population. Using herb-chronology, we found age structure did not differ between roadsides mowed several times during the growing season and grasslands mowed less frequently. However, we did find younger individuals in less frequently mowed grasslands had more stems and more flowering stems than those in more frequently mowed roadsides. Though plant age did not differ among the land uses and mowing regimes included in this study, our results suggest frequent mowing can negatively affect foliar and reproductive biomass of younger A. viridis plants. Limiting mowing during the early summer flowering season for A. viridis could support efforts to maximize host plant and nectar availability for monarchs and other pollinators.
Cites are relatively new landscapes for breeding Cooper's Hawks (Accipiter cooperii) that nest commonly in urban and rural habitats throughout North America. There is a call for data that may indicate if cities are low quality, sink habitats, as for some other raptors, or if cities function as high-quality, source habitats. Source habitats should exhibit high nesting densities, high reproductive output, and they should produce net emigration to sites that offer the potential for greater fitness. There are no reports of connectivity via dispersed individuals and their reproductive success (i.e., gene flow) between rural and urban subpopulations for Cooper's Hawks in North America. We report one of the highest nesting densities in North America, one nest/238 ha in the city of Oshkosh, Wisconsin in 2015, with regular spacing of nests suggestive of the saturated, stable population which occurs elsewhere throughout the state. Averages of 4.7 eggs and 4.1 nestlings per nest in Oshkosh, respectively, rank among the highest metrics for the species, and are similar to the stable and high reproductive indices found elsewhere throughout rural and other urban Wisconsin habitats across 34 y (1980–2015). An apparent low index of hatchling mortality rate (10%), or the loss of offspring from clutch to brood counts, was also found in Oshkosh. We detected both breeding and natal dispersal, with relatively high clutch and nestling counts, among eight individual Cooper's Hawks of both sexes moving into and emigrating from Stevens Point, Wisconsin with surrounding rural habitats. Most dispersal movements were less than 10 km. A relative similarity in maximum dispersal distances across 38 y (1980–2017) for rural-to-rural movements in males (35 km) and females (79 km), with those distances in males (27 km) and females (48 km) that moved between Stevens Point and its rural surroundings, suggest the maximum extent of natal dispersal movements is not habitat-specific in Wisconsin Cooper's Hawks. Discussion of various demographic contexts, including potentially confounding ecological variables, revealed limitations to previous reports and interpretations of reproductive output and nesting densities for the species, including assessments of habitat quality. We suggest high-quality rural and urban nesting habitats in Wisconsin are not source habitats for Cooper's Hawks within the state given none comparatively appears to offer the potential for greater fitness. Therefore, there should be no net dispersal among habitat types.
The evolution of colonial breeding remains an outstanding question in evolutionary biology due to our limited understanding of the costs and benefits of group living. We document 85 cases of Barn Swallows (Hirundo rustica erythrogaster) laying, and subsequently abandoning, eggs in empty, unclaimed nests located adjacent to active nests during a 6 y study. The frequency of this behavior was positively correlated with total available nests, a metric that increases with colony size. In addition, two female swallows were observed alternately incubating multiple clutches after mislaying eggs in neighboring nests. We argue the potential to mislay eggs and allocate parental care across separate nests may represent an overlooked cost of colonial nesting in birds.
Badger (Taxidea taxus) life history and ecology are poorly described despite widespread distribution in North America. We used radio-telemetry to estimate home range size and quantify habitat selection for badgers living in agricultural habitat in southwestern Wisconsin, U.S.A. Badgers in Wisconsin established relatively large home ranges (3 to 30km2), with those of males tending to be larger than females. Badgers selected broadly for nonforested grassland habitat in a matrix of agriculture, although fine-scale use varied substantially by individual. These patterns suggest that badgers tolerate levels of human alteration associated with agriculture in Wisconsin, although there may be limits to that tolerance.
Mammals commonly use latrines to communicate with each other via behaviors, such as scent marking and defecation. Olfactory cues resulting from these behaviors may influence the behavior of other species in and around latrines. The North American river otter (Lontra canadensis) is well known for its conspicuous use of latrines. We investigated whether latrine behavior of otters affected the behavior of other mammalian species. We used remote cameras to record activity patterns, visitation rates, and species richness at nine otter latrines located at five study sites across northern Indiana. We predicted the use of latrines by otters would result in the avoidance of latrines by other mammals in these riparian systems. Monthly mean species richness was lower at control sites than at latrine sites. Coyotes visited latrine sites more often than control sites, but all other species visited latrines and controls equally. Analysis of activity patterns revealed only white-tailed deer (Odocoileus virginiana) changed activity from primarily nocturnal at latrines to primarily diurnal activity at control sites. Our findings suggest otter latrine activity has minimal effect on the behavior of most other mammals. Therefore, surveying otter latrines with remote cameras may simultaneously provide unbiased estimates about the diversity of the riparian mammal community given mammals tended to visit latrine and control sites equally.
Black carp (Mylopharyngodon piceus) were imported to the U.S. in the 1970s to control snails in aquaculture ponds and have since escaped from captivity. The increase in captures of wild fish has raised concerns of risk to native and imperiled unionid mussels given previous literature classified this species a molluscivore. We acquired black carp from commercial fishers and biologists, and examined digestive contents of 109 fish captured over 8 y from lentic and lotic habitats in the central and southern U.S.A. Digestive tract contents were preserved, and diet items inventoried. We identified 59 aquatic animal taxa (21 mollusks, 27 insects, and 11 other invertebrates) and various plant material including nuts and seeds; no fish were found. Approximately 45% of stomachs examined were empty or only contained flukes (Trematoda) that had infected mollusks before they were ingested. Nonempty stomachs contained snails (16.5%), bivalve mussels (22.8%), and insect larvae (net-spinning caddisflies, 15.6%; burrowing mayflies, 6.4%; and midges, 13.7%). Fish also consumed freshwater sponges (Porifera), moss animals (Bryozoa), crustaceans (Ostracoda and Decapoda), water mites (Acarina), and three worm phyla (Nematoda, Nemertea, Annelida). Seven taxa of unionid mussels were identified from shell fragments among the fish we examined, all of which are found in habitats with soft mud or sand/silt substrates. Diet of fish captured in lentic environments contained significantly higher richness than those captured in lotic environments. Individual black carp often contained large numbers of only one or two diet items that were assumed locally abundant and did not always crush the shells of mollusks. Most fish we examined consumed benthic prey, which supports the classification of black carp as a benthic foraging species. However, the presence of other aquatic taxa associated with pelagic or subsurface zones suggests black carp are opportunistic in their consumption of diet items and flexible in their feeding modes.
The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 watersheds, possibly stable in 25%, possibly recovering in 8%, at risk in 33%, and possibly extirpated in 13% of the watersheds. The increasing trend in percent decline evident in earlier time periods reversed, going from 68% in 2010–11 to 40% in the most recent surveys. Following decades of decline, the status of Topeka shiners in Iowa appears to be improving. One potential reason for the reversal in the distributional decline of Topeka shiners in Iowa is the increasing number of oxbow restorations. Until a standardized monitoring program is established for Iowa, periodic status assessments such as this will be necessary to chronicle progress toward conserving this endangered fish species.
Smallmouth buffalo (Ictiobus bubalus (Rafinesque)) are an important component of the Middle Mississippi River commercial fishery. Despite their commercial importance, limited contemporary information is available regarding population age and growth. Therefore, the objective of this study was to determine age and growth of Middle Mississippi River smallmouth buffalo. To fulfill this objective, 125 individuals collected during routine Long-Term Resource Monitoring element hoop net surveys were aged via lapilli otoliths (mean age = 17.9 years; SD = 8.3), and a von Bertalanffy growth model (Lt = 730.289[1 - e-0.086(t-5.051)]) was used to evaluate growth. Our results indicate Middle Mississippi River smallmouth buffalo can achieve maximum ages beyond 20 y despite commercial harvest. Ultimately, we hope our results catalyze future research which seeks to understand other aspects of smallmouth buffalo biology and ecology.
From 2013–2018 crevices between segments of concrete barriers on the sides of 164 bridges in northern Arkansas were surveyed for bat presence on 1270 occasions and gray bats (Myotis grisescens) were found roosting in 21 bridges. Bats used bridges over streams of all sizes and did not select crevices based on width. Seventy-two bats (62 males, 10 females) were captured alive and two were found dead. Most bats were observed in the spring (62, 84%) with some observations in fall (10, 14%), and two (3%) juvenile males were found in the summer. In 75% of observations, a single gray bat was detected on the bridge. However, there were surveys in which multiple gray bats or gray bats and other species used the same crevice. This research provides a better understanding of the migratory patterns of this federally-endangered species.