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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 woody invasion and both burning and grazing reduce litter and grass cover, but careful consideration of timing, frequency, and intensity of application is required so management does not hinder fringed-orchid reproduction or reduce survival, while also recognizing management requirements may vary among years depending on weather. Long-term studies are particularly valuable for the western prairie fringed-orchid due to its erratic life cycle and fluctuating populations, which complicate studies of environmental and management effects on this species.
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 site shows severe barriers to selfing and strong pollen limitation. 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.
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 sampled 80 0.04 ha fixed area plots throughout the study area. Forest structure shifted from relatively large trees at low densities, with few small stems prior to European settlement to a relatively high density of small stems, with few large trees post-industrial logging. Although relative contributions of species varied over the past two centuries, forest composition remained relatively stable. Despite changes in land use, Pinus palustris remained the most common species in the forest.
Stream channel incision in the Piedmont of the southeastern US has resulted in a loss of stream and floodplain functions. Reduced flood frequency and lowered water tables typify incised low-order streams of the region. The objective of this study was to determine if a quantifiable shift in riparian vegetation community structure exists along a gradient of channel incision. Stream channel incision was described using bank height ratio (BHR), defined as the ratio of streambank height to bankfull depth. Ten low-order streams in the Alabama Piedmont were selected across a gradient of BHR values (1.0–5.2). Stream incision is strongly correlated with a shift of community type in the ground flora stratum, from wetland-adapted species at low degrees of incision to plants typical of upland settings at incised sites. Based on Nonmetric Multidimensional Scaling (NMDS) ordinations, functional composition of the ground flora layer was significantly related to median groundwater depth and BHR. These results suggest strong linkages between channel incision, subsequent lowered water table levels and decreased soil moisture, and herbaceous/ground flora composition in floodplains of the Alabama Piedmont.
Largemouth Bass (Micropterus salmoides) is a common predator and popular sport fish in tidal freshwater streams and lakes of North America. Tidal freshwater streams of Chesapeake Bay watershed, the largest estuary of the United States, differ remarkably in availability of submerged aquatic vegetation (SAV) and suitability for spawning habitat for M. salmoides. After scoring nursery habitat attributes of size and habitat quality, I combined scores to form indices for 141 nursery habitats of the Chesapeake Bay watershed. Average index for nursery habitat quality was positively related to the relative abundance of juvenile M. salmoides. For two important coastal fisheries for M. salmoides, over half of highly indexed nursery habitats were expected to be negatively impacted by projected sea level rise (SLR). Innovative strategies aimed at conserving populations of M. salmoides may include identifying habitats vulnerable to such long-term habitat changes and either protecting important habitats or managing future expectations for these populations.
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 in the fall. Our estimates of prey diversity and richness indicate that salamanders consumed a subset of available ant species. Aphaenogaster picea, an abundant species that prefers similar microhabitat characteristics to P. cinereus, made up a majority of the ants in the diet. However, our results indicate that P. cinereus avoids foraging on Myrmica punctiventris, Myrmecina americana, and Lasius alienus, ants that are among the most abundant species in the forested areas of northeastern Ohio where the study was conducted. These species are potentially aggressive and/or chemically defended, reducing their profitability as prey. The striped and unstriped morphs of red-backed salamanders foraged similarly on ant taxa, but the striped morph consumed significantly more ants and was found within territories that contained more ants. Our findings suggest selective foraging may be more common among generalist predators than previously considered, and we propose striped and unstriped morphs may represent a trophic polymorphism in P. cinereus.
We tested whether food availability affects extrapair paternity in House Sparrows (Passer domesticus) by providing supplemental food at their nests during some fertile periods but not others. When comparing broods produced by the same pair, a higher proportion of broods contained at least one extrapair young when food supplements were present, although the difference was not significant, and the proportion of extrapair young per brood was higher when food supplements were present, although again the difference was not significant. There was also little evidence that the presence of food supplements affected the amount of time spent at the nest by males, females, or both sexes at the same time. We also conducted two smaller experiments designed to either increase or decrease the rate at which individuals encountered one another but found no concomitant increase or decrease in the rate of extrapair paternity. Overall, we found little evidence food distribution affects extrapair paternity in House Sparrows.
Bighorn sheep (Ovis canadensis) were re- introduced into the Black Hills, South Dakota, U.S.A. in 1965. To date limited information exists concerning vital rates of this population. From 2010 to 2013, we estimated survival and cause-specific mortality of 55 adult female bighorn sheep in three herds in the east-central Black Hills. We documented 21 mortalities. Of those, pneumonia (19%) and predation (19%) accounted for most known causes of mortality; however, we were unable to ascertain cause of death for 47.6% of mortalities. We used a known fate analysis in Program MARK to estimate monthly survival; our best approximating model indicated survival differed during May–Jun compared with the remainder of the year. Monthly survival estimates for May–Jun were 0.95 (95% CI = 0.91–0.97) compared with 0.99 (95% CI = 0.98–0.99) for Jul–Apr, and overall annual survival was 0.81 (95% CI = 0.72–0.87). We found little support for the hypothesis that survival was influenced by body mass or nutritional condition (ingesta-free body fat). Our results indicated disease, predation, and other factors predisposing ewes to mortality, especially during and shortly after parturition, were contributors to the current demographic status of this population.
Space use information for native minks (Neovison vison) along river systems is insufficient due to either low sample size or exclusion of tributaries that minks readily use. We compared linear home ranges for 23 minks and compared daily movement distances between the Hudson River and its tributaries for 33 minks. Mean home range proportion for 12 minks that used both the Hudson River ( = 2.7 km) and its tributaries ( = 3.0 km) was not significant. However, daily movement distances were significantly greater along tributaries ( = 732 m) than along the Hudson River ( = 532 m), which may indicate differences in prey density between each of the waterbody types. The mean home range for 11 minks that strictly used tributaries was 4.7 km and the mean overall home range (waterbody types combined) for all 23 minks was 5.2 km. There was a significant difference in home range size between males (5.8 km) and females (4.1 km). This study contributes to the relatively few available ecological studies of native minks in North America and provides managers with linear space use information for minks along a large river system.
The American hog-nosed skunk (Conepatus leuconotus) is an understudied mesocarnivore for which no extensive ecological studies have been conducted. We radio-collared 29 skunks (15 male, 14 female) at a site in west-central Texas, U.S.A. and used data from 14 (5 male, 9 female) to determine patterns of home range and spatial organization. Home range (95% fixed kernel) of males averaged three times that of females (1.9 km2 vs. 0.64 km2) and extensive intrasexual and intersexual overlap in home ranges was documented. Female home ranges and core areas differed significantly in their topography (changes with which were associated with habitat difference) from those of males. Home range sizes were correlated with body size and gender, but intersexual differences between home range sizes and their topography indicate space-use patterns between male and female American hog-nosed skunks are influenced by factors beyond metabolic requirements alone. Specifically, we believe male home ranges are large to maximize encounters with females whereas females selectively choose areas to ensure availability of resources such as foraging and den sites.
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 distances between roosts. However, little brown bats switched roosts slightly less often than Indiana bats. 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 of crevice/cavity mimicking anthropogenic roosts during the spread of Europeans throughout North America.
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.
Occurrence of melanism in the coyote (Canis latrans) has been poorly documented. We collected 244 coyote carcasses throughout Florida during 2011–2014 and documented 18 cases of melanism (7.4%). Melanistic individuals were positively correlated with tree canopy cover (βcanopy mean = 0.11, se = 0.03, P < 0.001) and consequently observed only in northern portions of Florida. However, geographic trends (e.g., northing, easting, north-westing) did not explain variation in our data as well as habitat. Melanism varied through space from locally abundant to absent, but the drivers perpetuating variation in frequency of melanism are likely complex as the mechanisms for polymorphic maintenance are unclear.
After translocation a female greater prairie-chicken (Tympanuchus cupido pinnatus) traveled over 3988 km between 5 April 2013 and 20 June 2014. The bird traveled a mean distance of 21.5 km per day during the spring (median distance per day 22.2 km; range 0–115 km per day) moving through portions of four states. Nine other marked birds traveled a mean distance of 336 km and a mean distance per day of 7.5 km during the spring (median distance per day 4.6 km; range 0–92 km per day). This is the first record of movements of this magnitude by a greater prairie-chicken. This report highlights the use of recent advances in satellite/GPS telemetry methods for advancing our knowledge of wildlife movements.
The Topeka shiner Notropis topeka is a federally endangered fish species that is estimated to occupy only 20% of its historic range. In Iowa Topeka shiners have been in decline for decades. Our goal was to determine the present distribution of Topeka shiners in the west-central portion of their range in Iowa and to characterize the extent of its decline. We compared the current distribution to distributions generated from earlier collections. We found Topeka shiners in six of 22 watersheds where they occurred historically. Status of Topeka shiners was judged to be stable in 27% of the watersheds, at risk in 45% of the watersheds, and possibly extirpated in 27% of the watersheds. None were classified as increasing. Based on comparison of the historical distribution with more recent ones, Topeka shiners in west-central Iowa showed a 27% decline a decade ago and currently exhibits a 73% decline in their distribution. The collective evidence from four of five other states in the species’ range reveals similar declines. This study provides further information on the local distribution and extent of decline for this federally endangered species with a greatly reduced and fragmented overall distribution.