Showing papers in "American Midland Naturalist in 2021"

Ground Layer Microhabitats Influence Recruitment of Longleaf Pine in an Old-growth Pine Savanna

Abstract: Globally, savanna trees experience bottlenecks to recruitment. Likelihoods are low that juveniles, especially of nonclonal, reseeder species, will survive and reach sizes that survive recurrent fires. We hypothesized if ground layer vegetation within savannas contained patches with reduced fire effects, likelihoods of juvenile trees surviving fires would be increased. We refined our general hypothesis based on a field study in an old-growth southeastern pine savanna of North America, in which longleaf pine (Pinus palustris Mill.) is the most abundant tree. We hypothesized that recruitment of pines into the fire-resistant ‘grass stage’ may be more likely in three ground layer microhabitats (inside crowns of fallen pines, around pine tree stumps, and inside patches of oak/hardwood stems) than in surrounding groundcover located away from overstory pines. We measured the composition and abundance of ground layer vegetation and censused juvenile grass stages ( 5 times more likely inside the three microhabitats than in the surrounding ground layer matrix. Recruitment was also more likely in pine than oak/hardwood microhabitats. We propose that altered microhabitats, especially those generated by death of large longleaf pines, likely facilitate recruitment into populations of this reseeding savanna tree.

Ultraviolet Biofluorescence in Pocket Gophers

Abstract: Biofluorescence in mammal pelage is considered rare, but has been documented in multiple taxa in recent years. Herein, we provide the first observations of biofluorescence in fossorial mammals. We documented biofluorescence in live Geomys pinetis (southeastern pocket gopher) and in museum specimens of four additional geomyid species. Although unknown, the adaptive significance of biofluorescence in pocket gophers is likely similar to that documented in terrestrial and arboreal species previously, including communication or predator evasion.

A 20 y Analysis of Weather and Management Effects on a Small White Lady's-slipper (Cypripedium candidum) Population in Manitoba

Abstract: The small white lady's-slipper, Cypripedium candidum, is a rare perennial orchid with a limited distribution in Canada, occurring as isolated populations in remnant tallgrass prairie in southern Manitoba and Ontario. The species is listed as endangered in both provinces and as threatened federally. Despite its status, information on how environmental conditions and land management affect population size and persistence of this species is limited. We used 20 y of monitoring data collected for a subset of the largest population in Canada to evaluate the response of small white lady's-slipper to land management and weather. Long-term monitoring suggests the population is in decline and may not persist under the current climate and management regime. Temperature appears to regulate vegetative growth and flowering proximately. Warm temperatures early in the spring, when shoots are emerging, appear favored, but high temperatures during anthesis appear detrimental, reducing both vegetative growth and flowering. In contrast, precipitation appears to have a lag effect on growth and flowering. However, snow depth was identified as a positive influence on vegetative growth, suggesting precipitation in early spring, when shoots are emerging, is also important for above-ground growth. Some grazing appears to benefit the species presumably by reducing competition and shading, but frequent grazing may increase the risk of direct damage to individuals from cattle consumption and trampling and does not provide sufficient time for individuals to recover following grazing events. Our findings add to the knowledge of orchid conservation and management, highlighting the importance of long-term monitoring in detecting population trends in species with erratic life cycles and fluctuating populations, such as the small white lady's-slipper.

Regulation by the Pitcher Plant Sarracenia purpurea of the Structure of its Inquiline Food Web

Abstract: Phytotelmata, the water-filled habitats in pitcher plants, bromeliad tanks, and tree-holes, host multitrophic food webs that are model experimental systems for studying food-web structure and dynamics. However, the plant usually is considered simply as an inert container, not as an interacting part of the food web. We used a manipulative field experiment with a response-surface design to determine effects of nutrient enrichment (multiple levels of NH4NO3, PO4, and captured prey), top predators (removed or present), and the plant itself (with or without plastic tubes inserted into the pitchers to isolate the food web from the plant) on the macrobial food web within the modified leaves (“pitchers”) of the carnivorous pitcher plant Sarracenia purpurea. Connection to the plant, addition of NH4NO3, and removal of the top predator significantly increased the food web's saturation, defined as its trophic depth and number of interactions. No effects on food-web saturation resulted from addition of PO4 or supplemental prey. Plants such as S. purpurea that create phytotelmata are more than inert containers and their inhabitants are more than commensal inquilines. Rather, both the plant and the inquilines are partners in a complex network of interactions.

Decomposition of Leaf Litter from Native and Nonnative Woody Plants in Terrestrial and Aquatic Systems in the Eastern and Upper Midwestern U.S.A.

Abstract: Leaf litter decomposition plays an important role in nutrient cycling in both terrestrial and aquatic systems. Decay rates vary based on species, habitat, climate, and local environmental conditions. Invasive plants alter decomposition processes; however, there is a lack of research exploring patterns at regional and continental scales. In this study we examined the decomposition of both native and nonnative, invasive woody plant leaf litter and mixtures of the two, in both terrestrial and aquatic habitats at nine locations in the eastern and midwestern U.S.A. There was significant variation among locations, which was not clearly related to either average air temperature or precipitation. Unexpectedly, in locations with multiple years of data, there were higher rates of decomposition in years with lower temperatures and precipitation in both terrestrial and aquatic habitats. We found decay rates were generally higher in aquatic than terrestrial habitats and leaf litter from nonnative invasive species generally decayed faster than that of native species in both terrestrial and aquatic systems. Differences in litter decay rates among invasive species were significant in both terrestrial and aquatic habitats; whereas no differences were found among native species in either habitat. In mixed litter bags, decay rates were lower than what was predicted based on the relative amounts of native and invasive litter in each bag, possibly indicating the presence of native leaf litter slows the decomposition of invasive leaf litter. Additionally, there may have been threshold effects in the mixed litter bags, especially in aquatic systems. While this study supported several generalizations about leaf decomposition rates (invasive > native, aquatic > terrestrial), the variability in the decay rates from different locations and habitats indicates combinations of different species and local conditions may overshadow other general trends related to litter decomposition.

Spatial and Temporal Variation in Length-Weight Relationships of Age-0 Scaphirhynchus Sturgeon in the Lower Missouri River

Abstract: Length-weight relationships can be useful tools for assessing fish condition. We developed these equations (W = aLb) for wild-caught age-0 (4.1–12.0 cm) Scaphirhynchus sturgeon from eight reaches spanning over 750 river km of the lower Missouri River from 2014 to 2017. We used nonlinear modeling to estimate the constant (a) and exponent (b) of the LW equation for each reach to assess potential spatial differences. We also assessed long-term temporal effects by estimating these parameters by year at Lexington reach, which is located in the middle of our sampling area and was the only reach sampled all 4 y. Constant and exponent estimates from linearized regressions varied by reach and were inversely related during the spatial analyses. Similarly, parameter estimates were also inversely related and varied among years during the temporal analysis at Lexington. To account for the relationship between constant and exponent values, we used predicted weights at 2 cm increments (4.1–12.0 cm) for the spatial analysis (by reach) and for the temporal analysis (by year). During the 2014 and 2015 spatial analyses, weights varied by size but were usually higher in Lexington and Glasgow, which were the furthest upstream reaches sampled during those years. During 2016 and 2017, Lexington was the furthest downstream reach sampled but did not consistently yield relatively high predicted weights. Temporal analysis at Lexington yielded higher predicted weights for 2014–2015 compared to 2016–2017 for higher size categories (10- and 12-cm). In general our results suggest differences in body condition among reaches and years in the lower Missouri River. Further research is needed to identify the specific mechanisms driving spatial and temporal L-W relationship differences observed and to determine if differences in predicted body conditions affect long-term survival and recruitment of age-0 Scaphirhynchus sturgeon. Currently, factors influencing age-0 Scaphirhynchus sturgeon condition and growth are unknown and this work serves to highlight knowledge gaps regarding factors influencing Scaphirhynchus sturgeon recruitment.

Assessing Linkages Between Small Impoundments and Long-term Trajectories of Prairie Stream Fish Assemblages

Abstract: Most stream fish communities have changed over time in response to common anthropogenic disturbances. Impoundments are a widespread anthropogenic stressor that can negatively impact stream fishes as they alter flow regimes, block movements, and act as fountainheads for the introduction and spread of invasive species. Recent studies, however, have reported the occurrence and reproduction of native fishes in impoundments, suggesting they might benefit some native fishes. Our primary objective was to evaluate whether impoundment construction has led to changes in fish community structure in prairie streams. To accomplish this, we compared fish occupancy in small impoundments (,5 ha) to temporal trends in stream occupancy among species to test whether species' increases in stream occupancy were related to their occupancy in impoundments. We examined stream fish communities in the Upper Cottonwood River basin, Kansas, from 1948–2018, and sampled small impoundments in 2016 and 2017. A third (32%) of fish communities in impoundments were similar to stream assemblages, whereas most impoundments (68%) were dominated by sport or bait fishes. In streams, six species showed increases in occupancy and four species showed decreases since small impoundment construction. Of the species that exhibited increased stream occupancy, five showed a positive, logistical relationship between a species' impoundment occupancy and its increase in stream occupancy. Species declining in stream occupancy experienced continued linear declines and may still be declining. Our research suggests stream fish communities have changed since impoundment construction, and are associated with locally-invasive, native species reaching a new stable state in streams accompanied by declines in other native stream fish species.

The Rocky Road to Eastern Hellbender (Cryptobranchus a. alleganiensis) Recovery in Ohio: An Evaluation of Habitat in Ohio's Streams

Abstract: Determining habitat characteristics that influence the contemporary distribution of species is imperative for effective conservation planning. The Eastern Hellbender (Cryptobranchus a. alleganiensis) reaches its Midwestern northern range limit in Ohio, U.S.A.Most previous studies have focused on habitat within the mountainous core of the species' range. We assessed physical and chemical habitat characteristics across the extant range of the Hellbender in Ohio. Physical habitat characteristics were similar to habitat across the range. Hellbenders occupied stream segments typically in contact with steep hillsides that are the source of large shelter rocks. Stream substrate consisted of large boulders and cobble and contained moderate proportions of gravel and sand. Both water temperature (max = 29.4–33.0 C) and conductivity (range = 284–1323 µS/cm) were elevated in Ohio streams. Historic alterations to streams in combination with distinct hydrologic regimes and geology have resulted in habitat characteristics not commonly reported elsewhere. This may have contributed to Hellbender populations being dominated by large adults. Developing an understanding of the role habitat structure and perturbations play in egg and larval survival is critical for the implementation of effective conservation strategies.

Roost Use and Movements of Northern Long-Eared Bats in a Southeast Nebraska Agricultural Landscape

Abstract: Bats are important bio-indicators of ecosystem health and provide a number of ecosystem services. White-nose Syndrome and habitat loss have led to the decline of many bat species in eastern North America, including the federally threatened northern long-eared bat, Myotis septentrionalis. White-nose Syndrome was only recently found in Nebraska, which lies on the western extent of this species geographic range. To better understand how this forest-dependent species persists in an agriculturally dominated landscape amid a growing number of pressures, we investigated the roosting habits of this bat at the Homestead National Monument of America, located in southeast Nebraska. We mist-netted bats on eight nights in 2019 (16 August–26 August) and caught 55 bats across five species, including five juvenile northern long-eared bats. We located five unique roosts between two juvenile radio-tracked bats; most of the female roosts were in anthropogenic structures and tree cavities within 0.23 km of capture, while most of the male roosts were in snags and tree cavities as far as 2.73 km from the capture site. Fence cavities were also used by other undocumented northern long-eared bats. We recorded three radio-tagged bats that commuted between roosting sites and capture sites within hours after sunset. Our results provide evidence that at the distributional edge for this species, wooded areas, riparian zones, and human-built structures in an intensively managed agricultural landscape are used by this imperiled species.

One House is a Home for Many: Temporal Partitioning of Vertebrates on an American Beaver Lodge

Abstract: American beavers (Castor canadensis) are emblematic of diverse and dynamic freshwater ecosystems across North America. Numerous studies have described positive associations between beaver-modified habitats and biodiversity across a wide range of taxa. Yet few studies have documented biodiversity associated with the epicenter of beaver-modified habitats – the beaver lodge. We used an internet-connected, solar-powered, time-lapse camera system to examine daily and seasonal temporal partitioning amongst vertebrate taxa that visited an American beaver lodge in south-central Nebraska over 9 mo. We observed at least 28 species on the lodge, and many organisms were present during discrete daily and seasonal time periods. These observations provide a more holistic view of a widely recognized, yet understudied, component of beaver-modified habitats. Future use of similar visual-recording systems may reveal that other animal structures, such as burrows, nests, and hives, are prominent ecosystem components in the wild.

Influence of Forest Fragment Composition and Structure on Ground-Dwelling Arthropod Communities

Abstract: Habitat fragmentation is the process of reducing habitat area while increasing the number and isolation of habitat patches. Although much of Indiana's land area was historically covered with contiguous forests, remaining forests are now heavily fragmented. This is especially true in northeastern Indiana where agriculture is the dominant land use cover type. Loss of functional forests in northeast Indiana could lead to a loss of biodiversity at a regional scale. Ground-dwelling arthropods have been used frequently as biological indicator taxa of forest health. We characterized 10 typical northeast Indiana forest plant communities and inventoried ground-dwelling arthropod communities within those forests. Plant community and environmental heterogeneity within forests were used to assess forest complexity, and ground-dwelling arthropod communities were compared to forest environmental characteristics. Our forest comparisons revealed plant community and structural heterogeneity differences. While overstory and understory diversity, compositional heterogeneity, and litter depth did have influence on arthropod communities' relative dissimilarities in nonmetric multidimensional scaling ordination plots, those communities were similar across all forest patches. However, those same environmental variables did not have direct influence on overall arthropod abundance, richness, or diversity. Even though differences did occur in forest structure and composition, arthropod communities had high similarity values, especially in August. As the forests in the region are similar in type and structure, between-forest comparisons of arthropod communities showed corresponding similarities in composition, abundance, richness, and diversity.

Limited co-existence of native unionids and invasive dreissenid mussels more than 30 Y post dreissenid invasion in a large river system

Abstract: There are serious concerns for native freshwater mussel survival (Bivalvia: Unionidae) in the Laurentian Great Lakes region after populations were seemingly pushed to the brink of extirpation following the introduction of dreissenid mussels (Dreissena polymorpha and D. rostriformis bugensis) in the mid-1980s. The Detroit River was the first major river system in North America to be invaded by dreissenids, and unionids were considered extirpated from the river by 1998. Since then several unionid refuges (areas with relatively low dreissenid impact and surviving unionids) have been found in coastal areas of lakes St. Clair and Erie, but no documentation exists in the Detroit River. To assess dreissenid presence and potential unionid persistence, a mixture of stratified random, historical, and potential refuge sites were surveyed during summer 2019 in the Detroit River. Unionid and dreissenid habitat use was further investigated with analysis of variance and classification tree analyses. Of the 56 sites surveyed, only five sites had live unionids totaling 220 animals of 11 species. More than 2000 unionid shells of 31 species were collected from 39 sites, confirming the large and diverse unionid populations that existed prior to the dreissenid invasion. Ninety-eight percent of live unionids found showed evidence of past or present dreissenid attachment. Estimated dreissenid densities were highly variable with river location and ranged from 0 to 5673 live individuals per m2, with the largest densities concentrated in the upstream half of the Detroit River. Despite their previously assumed extirpation from the Detroit River, live unionids were found during this comprehensive survey. Although only 40% of the historical species within the unionid assemblage remains, our results suggest, in the right conditions, some coexistence is possible among some species of unionids and dreissenids in this large river system.

Assessing the Impacts of Prescribed Fire and Bison Disturbance on Birds Using Bioacoustic Recorders

Abstract: Grassland bird responses to grazing and prescribed fire are species-specific and are primarily known from systems with cattle as the predominant grazer. There is less knowledge of how grazing by bison impacts grassland birds, especially in sites restored and reconstructed from row-crop agriculture. Working at a tallgrass prairie site consisting of restored and remnant prairie in the years following bison reintroduction and ongoing prescribed burning, we assessed overall species richness and the relative detection frequency of five focal species (Grasshopper Sparrow, Henslow's Sparrow, Dickcissel, Eastern Meadowlark, and Brown-headed Cowbird). We used stationary bioacoustics recorders to record the soundscape during the summer breeding season in areas with and without bison from 2016 to 2018. Species richness and the detection frequencies of our focal species were not influenced by bison disturbance. Grasshopper Sparrow and Dickcissel detection frequency increased slightly in response to prescribed fire, whereas Henslow's Sparrow detection frequency decreased. Time since sites were restored was a predominant factor that influenced the variation in detection frequency of Henslow's Sparrows and Eastern Meadowlarks, likely due to vegetation differences in restored versus remnant sites and each species' vegetation structure preferences. Brown-headed Cowbird detection frequency was unaffected by bison presence, prescribed fire, or time since restoration, but varied among sampling years. Our focal species showed no response to bison disturbance 4 y after the bison reintroduction. This suggests there could be a time-lag for a response or that these species will not respond to the bison reintroduction at this study site.

Effects of the Interaction of Bluegill and Two Species of Tadpoles on Experimental Zooplankton Communities

Abstract: Fish predation can structure zooplankton communities; however, the impacts of other organisms on zooplankton communities, alone or interacting with fish predation, are less known. We used two mesocosm experiments to study the impacts of Bluegill (Lepomis macrochirus) and tadpoles on temperate zooplankton communities, one with American Toad tadpoles (Anaxyrus americanus) and the other with Bullfrog tadpoles (Lithobates catesbeianus). In both experiments Daphnia (a larger bodied cladoceran) were virtually eliminated and rotifers were more abundant with Bluegill. Bluegill slightly reduced cyclopoid copepods in the American Toad experiment but not significantly, whereas cyclopoid copepods were more abundant with Bluegill in the Bullfrog experiment. Bosmina (a smaller bodied cladoceran) in the Bullfrog experiment were more abundant when Bluegill were absent, but there was no significant effect of Bluegill in the American Toad experiment. Tadpoles in general had no effect on our zooplankton communities. Our experiments confirm the influence of Bluegill on zooplankton communities, whereas tadpoles of the two anuran species had no widespread effects on zooplankton.

The Prevalence of the Raccoon Roundworm, Baylisascaris procyonis, in Allegheny Woodrat Habitat in the Mid-Atlantic Region, U.S.A.

Abstract: Baylisacaris procyonis is a roundworm that is tolerated by its primary host, raccoons (Procyon lotor). However, this roundworm can be fatal to intermediate mammalian hosts and may be a contributing factor to population declines of the endangered, Allegheny woodrat (Neotoma magister). We used fecal flotation to determine the prevalence of B. procyonis eggs in raccoon scat found in locations that overlap with where woodrats persist in the mid-Atlantic. We determined that B. procyonis was present at two extant woodrat colonies in Maryland and Pennsylvania. We expect woodrat populations at these sites to decline, if the roundworm and other factors (e.g., forest fragmentation) are not alleviated.

Understanding Habitat Use and Activity Patterns of Ornate Box Turtle (Terrapene ornata) in Eastern New Mexico

Abstract: The ornate box turtle (Terrapene ornata) is a terrestrial Emydid, listed as near threatened by the International Union for Conservation of Nature Redlist due to habitat destruction, degradation, habitat fragmentation, commercial harvest, and road mortality. Terrapene ornata is secretive, which can pose a challenge to conducting systematic surveys and assessing species status. Studies on the species' biology have relied on opportunistic encounters on the road and the use of radiotelemetry. The objective of this study was to assess the feasibility of using transect line surveys in single season occupancy surveys for T. ornata in Roosevelt County, New Mexico. We further used radiotelemetry to link turtle activity patterns with environmental conditions to aid in understanding detectability of the species. Our occupancy model showed the detection probability to be influenced by individual observers and the time of day. We found T. ornata to most likely occupy habitats with less dense ground cover and avoid highly altered habitats (i.e., cultivated fields). Radiotelemetry further revealed the effect humidity, time of day, and temperature on turtle activity patterns. The lowest activity occurred between 1200–1700 h, whereas peak activity occurred in early morning hours (0600–0900 h). The peak activity occurred between ∼10–25 C and was promoted by higher humidity. Our study represents the first attempt at using transect line surveys for occupancy modeling framework for the ornate box turtles. We suggest that future studies on box turtle occupancy focus on finer scale habitat assessment that would also include vegetation, invertebrate, and small mammal surveys.

Assessing the Effect of Eastern Hemlock (Tsuga canadensis) Decline from Hemlock Woolly Adelgid (Adelges tsugae) Infestation on Ectomycorrhizal Colonization and Growth of Red Oak (Quercus rubra) Seedlings

Abstract: Eastern hemlock (Tsuga canadensis (L.) Carriere) is a foundation species in eastern North American forests, providing critical habitats for a number of species. These trees are experiencing widespread decline due to the spread of hemlock woolly adelgid (HWA: Adelges tsugae Annand Order Hemiptera) into their range, potentially resulting in the disappearance of hemlocks from eastern forests. Hemlock dieback can lead to cascading effects on associated ecosystems, including belowground, mycorrhizal fungal communities. Ectomycorrhizal fungi (EM), which are mutualistic with many tree species and provide nutrients to plant hosts, are known to colonize hemlock as well as neighboring tree species at lower levels following HWA infection. This study investigated the effect of hemlock decline from HWA infestation on mycorrhizal communities, as inferred from colonization on northern red oak (Quercus rubra L.) “bait” seedlings grown near “host” hemlock trees. Hemlock health surveys were conducted in healthy (Carl Sandburg Home National Historic Site – CARL) and declining (Warren Wilson College – WWC) stands in western North Carolina, and host trees were paired between stands based on diameter. In each stand, northern red oak seedlings were planted within a meter of host hemlocks in early summer and allowed to grow for 8 w, when they were harvested. Seedling growth and dry biomass were recorded at harvest and roots were sampled for mycorrhizal colonization frequencies. Different mycorrhizal morphotypes were collected from seedling roots for subsequent DNA barcoding analyses to characterize EM taxonomic richness to compare mycorrhizal community assemblages between the two stands. Mycorrhizal colonization frequencies (percentage of the total number of EM-colonized root tips per seedling) and growth in seedling height were significantly greater at CARL than WWC, suggesting healthy hemlock stands are more favorable for oak seedling growth than declining stands. Moreover, a greater proportion of seedlings grown in the healthy stand were colonized by EM, indicating EM assemblages differ between a healthy and a declining hemlock stand. Differences between EM communities corresponded with altered seedling growth allocation, as seedlings in the declining stand had higher root to shoot ratios with reduced stem height, but showed greater investment in root biomass and stem diameter growth. We conclude EM communities differ between a healthy and declining hemlock stands, and changes in EM communities following hemlock dieback may affect the growth of replacement species.

Effects of the Herbicide Metolachlor and Fish Presence on Pond Mesocosm Communities

Abstract: The effects of many pesticides on aquatic ecosystems remain poorly understood, especially in naturalistic communities in which organisms are connected by a complex array of direct and indirect interactions. Moreover, multiple stressors can interact, and the addition of apex predators, such as fish, may introduce additional ecosystem changes that exacerbate or mitigate pesticide effects. Despite being both common and environmentally persistent, the effects of the herbicide metolachlor on realistic aquatic communities have received insufficient research attention. We tested the effects of metolachlor on pond mesocosms at three concentrations (0, 20, and 80 ppb), along with the presence vs. absence of fish (black crappie, Pomoxis nigromaculatus) to determine the independent and combined effects of these two environmental changes. We found both metolachlor and fish altered the pond mesocosms, but their effects did not interact. Metolachlor reduced phytoplankton as expected, but had nonlinear effects on dissolved oxygen. Metolachlor also altered tadpole behavior, making them less prone to hiding. Fish presence increased periphyton and decreased snail counts, as well as changing the behavior of tadpoles, reducing their hiding behavior. This work demonstrates previously undocumented effects of metolachlor in the presence and absence of fish and suggests future avenues of investigation.

Regal Fritillary (Speyeria idalia) Sex Ratio in Tallgrass Prairie: Effects of Survey Timing and Management Regime

Abstract: The regal fritillary, Speyeria idalia (Drury), was once a common inhabitant of North American grassland communities. Regal fritillary populations are commonly reported to have a male biased adult sex ratio (ASR) throughout their range. We assessed the observed ASR of regal fritillary throughout an annual flight period, investigated how the overall density of both sexes changed, and tested effects of prescribed fire, grazing and haying management treatments on male and female density. We found that regal fritillary exhibited an observed 2:1 male biased ASR across the entire emergence period. Our analysis also revealed that male density peaked earlier than female density in the flight period. Point estimates of density indicated sites that received prescribed burning at the moderate fire-return interval supported ≥1.3 times greater density of males and ≥5.6 times greater density of females versus sites burned with short and long fire-return intervals. Additionally, this effect was enhanced when combined with grazing which showed males were ≥1.9 times and females had ≥1.2 times greater point estimates of density in sites that were grazed and burned at a moderate fire-return interval versus other sites. The relatively stable status of regal fritillary within our study region suggests that a 2:1 male to female ASR may be considered the model composition of populations throughout their range. Likewise, the dynamic nature of the ASR throughout the flight period highlights the importance of conducting surveys across the flight period. Finally, these results corroborate an increasing number of research results that reveal common prairie management practices, such as prescribed fire can be applied within sites that contain regal fritillary and continue to support stable populations.

Vigilance Patterns of Black-Tailed Prairie Dogs (Cynomys ludovicianus) in Urban and Rural Areas

Abstract: We analyzed the relationship between landscape context and the vigilance and foraging patterns of the black-tailed prairie dog (Cynomys ludovicianus) in urban and rural areas. We observed five colonies, two in urban areas and three in rural areas from 23 March–20 April 2016, 31 August–19 September 2016, 26 March–12 April 2017, and 7 September–17 October 2017. We measured vigilance by observing individual prairie dogs for 5 min and recording the amount of time the individual spent vigilant or foraging. In addition, the total number of individuals in the colony that were actively vigilant or foraging were counted every 10 min for 1 h. Prairie dogs in rural colonies were more vigilant than those in urban colonies and displayed a lower proportion of individuals that were non-vigilant in both the spring and summer. Because prairie dogs in urban colonies might be habituated to disturbance and have a relatively low risk of predation, individuals spent much less time vigilant. Our findings could be used to better understand behavioral changes in black-tailed prairie dogs caused by encroaching urban development.

To Establish a Healthy Forest: Restoration of the Forest Herb Layer on a Reclaimed Mine Site

Abstract: Restoration efforts, such as invasive species removal and establishment of native flora, can be resource intensive. Therefore, understanding the effectiveness of restoration efforts can provide land managers with the confidence to pursue restoration. This study evaluated the effects of invasive species removal and compared active revegetation to passive revegetation in enhancing forest integrity on reclaimed surface coal mine land in southeastern Ohio. Surface coal mining occurred in the area from the 1940s to the 1980s, leaving a near continuous disturbance footprint of 3704.5 ha. This study occurred within 3.6 ha of the larger disturbance footprint where mining activity ceased and reclamation with tree planting occurred in the 1960s. Due to the disturbance, the site was prone to invasive species until their removal began in 2017. In spring 2019, 2 y following invasive species removal and 1 y following seeding and planting, we completed vegetation and bloom surveys across three treatments: managed forest with invasive species removed and subsequent native plantings (planted), managed forest with invasive species removed only (unplanted), and unmanaged forest (control). Our study found vegetative species diversity, vegetative species richness, and floral species richness and bloom time were enhanced for treatments in which invasive species were removed. The planted and unplanted treatments also supported understories comprising a different community composition when compared to control plots. However, no difference was found in community composition between planted and unplanted treatments despite application of active revegetation to support understory regeneration. Overall, results after 2 y support invasive species removal to improve the herbaceous layer of an understory, with more time likely needed for planted material to establish in order to distinguish between revegetation methods.

A Comparative Analysis of Adult Sex Ratios in Polygynous and Monogamous Mammal Populations

Abstract: An inverse density-dependent relationship between abundance and adult sex ratio (ASR, males:female) occurs in some populations of polygynous mammals due to life history differences between the sexes. Male fecundity and survival is dictated by attempts to obtain as many copulations as possible, whereas female fecundity and survival is dictated by resource acquisition. Therefore, females usually acquire forage before males as a result of interspecific scramble competition, particularly when forage becomes more limited at K carrying capacity. This leads to the passive displacement of males in a given area. The common belief is that most monogamous mammal populations exhibit balanced adult sex ratios. The coupling of sexually mature males and females in a population result in this pattern for this mating system. Present literature focuses on primary or secondary sex ratios in mammals or on ASR patterns within individual species. Our goal was to test if expected ASR patterns would be visible across numerous species in both mating systems. We hypothesized we would see an inverse relationship between abundance and ASR across polygynous populations, and no relationship between abundance and ASR across monogamous populations. We extracted time series population data from published literature for 43 populations of 15 different mammal species. Results from our analysis of a linear mixed-effects model were consistent with our hypothesis for polygynous populations, as we found a significant inverse relationship between abundance and ASR. However, our analysis also revealed a significant inverse relationship between abundance and ASR in monogamous populations that was not consistent with our hypothesis. Our findings provide quantitative support for a theoretical model explaining the evolutionary and ecological mechanisms driving a density-dependent relationship between abundance and ASR in polygynous mammals. An investigation into monogamous mammals is needed to assess why some species with this mating system display a density-dependent response in ASR as well.

Exploring the Origins of Red Foxes (Vulpes vulpes) on Isle Royale

Abstract: Isle Royale National Park is generally considered a pristine ecosystem, but the island archipelago has a long history of human impacts that have altered the island's mammal communities through extirpations and introductions. The origin of red foxes (Vulpes vulpes) on the islands are of particular interest given their ubiquity and uncertain colonization history. Red foxes were first reported on Isle Royale in 1925, shortly after the foundation of a small fox farm that began on Isle Royale in 1922. We sequenced two mitochondrial haplotypes from red fox scats collected on Isle Royale and compared them to haplotypes from the mainland surrounding Lake Superior, the predominant source of the island's other native mammals. Some Isle Royale foxes matched widespread haplotypes commonly found across Canada, but over half of our samples matched haplotypes previously detected only in Newfoundland. While we cannot conclude a singular origin, we offer a working hypothesis red foxes on Isle Royale are derived from a combination of natural colonization and human introduction. Specifically, we propose native red foxes may be admixed with fur-farmed foxes from an introduction in the early 20th century.

Seasonal Space Use and Movement of a Grey Wolf (Canis lupus) in a Protected Archipelago in Lake Superior, Ontario

Abstract: Data on movement of grey wolves (Canis lupus) in island systems is largely restricted to coastal environments and little is known about their space use and movement in freshwater archipelagos. We used data from a GPS-collared wolf in a protected archipelago in Lake Superior, Ontario to examine broad seasonal patterns in space use, movement, and activity. Over approximately 1 y of monitoring, the wolf made 190 crossings between islands and showed more extensive use of the archipelago during the nonwinter season. When ice was present in the archipelago, the mean weekly inter-island crossing rate of the wolf (± se) was 6.08 ± 1.31, with crossings largely restricted to the interior islands bounded by ice, compared to 2.85 ± 0.45 during the open water season. Mean wolf activity was highest in the nonwinter season, but movement rates were comparable across seasons. Our study is the first to document wolf movements in a freshwater archipelago with seasonal ice cover and supports data collection at fine temporal scales to better understand trends in wolf space use and movement at small spatial scales.

High-Frequency Photographic Imaging Provides Novel Insights into Nesting Bald Eagle Diet and Opportunities for Public Engagement

Abstract: Bald eagles (Haliaeetus leucocephalus) were formerly endangered in the contiguous United States, but have since recolonized much of their past range. Maintaining bald eagle populations following recovery requires knowledge of factors that influence nesting success, including food habits during the brood-rearing period. We examined over 26,000 images from a high-resolution, above-nest digital camera to document the diet of a nesting bald eagle pair in north-central Indiana, U.S.A., during the 2018 brood-rearing period. After the hatch of two eaglets in April 2018, the camera was programmed to take still photos of the nest every 20 min, in addition to live-streaming video to YouTube for public audiences. Still images were used to quantify and identify all prey deliveries to the lowest taxonomic level possible, typically species. A total of 135 prey items and at least 26 prey taxa were recorded during the 75 d of the study, although daily prey count became uncertain in the final 20 d as fledglings began to move out of camera view. The majority of recorded prey items (73%) were fish, with redhorse suckers (Moxostoma spp.) representing the most numerous of the 13 fish taxa observed. Smaller numbers of birds (13%), mammals (10%), and reptiles (4%) were also observed. Although our results represent one nest across a single brood-rearing season, we gained novel insights through the analysis of high-frequency, high-definition images that provided increased temporal and taxonomic resolution of prey deliveries. The use of a camera not only avoided historical biases in bald eagle diet analysis, but also provided a valuable tool to engage public audiences.

Breeding Bird Occurrence Across a Gradient of Graminoid- to Shrub-Dominated Fens and Fire Histories

Abstract: Population declines of birds affiliated with grasslands and grass-shrub habitats have been identified as a critical conservation concern. The effects of woody encroachment into grassland-dominated systems, which may contribute to species declines, has been examined mainly in upland systems. We examined occurrence of bird species across a gradient of graminoid- to shrub-dominated wetlands in the Upper Peninsula of Michigan and describe the habitat characteristics associated with their probability of occurrence at segment (100 × 100 m) and landscape (200 m buffer) scales. Because fire can suppress woody encroachment, we also examined the role of fire history, extending from 50 y on birds and habitat characteristics. We focused on seven species closely affiliated with grassland and grass-shrub habitats, but also found in wetlands: Sedge Wren (Asio flammeus), LeConte's Sparrow (Ammodramus leconteii), Savannah Sparrow (Passerculus sandwichensis), Bobolink (Dolichonyx oryzivorus), Common Yellowthroat (Geothlypis trichas), Swamp Sparrow (Melospiza georgiana), and Alder Flycatcher (Empidonax alnorum). We used nonparametric, multiplicative regression models to relate habitat variables and fire history to probability of species occurrence. Unlike studies in upland grasslands, none of the top models included measures of litter or graminoid height, and the highest probability of occurrence often was where graminoid cover was at intermediate rather than highest levels. Measures of woody cover or structure were important to all seven species modeled. We observed few clear differences in habitat metrics across fire history categories beyond the first year of burning. Years since last burned was in the best model for four of the seven species, despite high variability of habitat metrics within fire history categories; those species were more likely to occur in segments burned 15–19 y earlier. Infrequent light- to moderate-severity fires in fens had little effect on focal species occurrence beyond the first year after burning and little long-term effect to suppress woody cover.

Operational Impacts of a Water Management Structure on the Surrounding Fish Assemblages in a Restored Backwater and a Large Floodplain River

Abstract: Water management structures (WMS) are used to regulate water levels between large floodplain river backwaters and their adjacent river systems offering a balance between maintaining quality backwater habitat and providing benefits to the river systems. The design and operation of these WMS is dependent on unique management goals, and their impacts on the surrounding ecosystem are understudied. From 2016–2018 we quantified the response of the surrounding fish assemblages (i.e., backwater and river abundance and composition) to the WMS operation at the Emiquon Preserve, a 2723 ha restored floodplain lake located adjacent to the main channel of the Illinois River, U.S.A. Environmental conditions were recorded, and fish were collected using boat electrofishing on both sides of the WMS under three operational levels: closed and no flow, gravity flowing water, and mechanically pumping water to the river. Multivariate analyses determined that there was no difference in fish community composition within the Emiquon Preserve among operation levels. Within the river there were differences in community composition when the WMS was closed and mechanically pumping water. Environmental parameters varied seasonally and WMS operation level varied but indicated an increase in chlorophyll-a in the river when the WMS was mechanically pumping water, although the chlorophyll-a decreased within 200 m downstream of the WMS in the Illinois River. This study suggests that managed connections between restored backwater and habitats operated like this WMS have variable, spatially isolated impacts on fish communities despite supplying chlorophyll-a to large river ecosystems.

Long-lived Female Wolverines (Gulo gulo) Documented at the Southern Edge of Recolonization

Abstract: Wolverines (Gulo gulo) were nearly eliminated from the contiguous U.S. by the mid-1920s, when they began to naturally recolonize portions of their historical range. Currently, the Greater Yellowstone Ecosystem in Wyoming represents the southernmost distribution. Using remote cameras, we detected two female wolverines in 2016 and 2017 in Wyoming, originally captured as juveniles. At nearly 11 and 12 y old, both were documented in the same areas where they appeared to set up home ranges previously, suggesting continued residency. The presence of long-lived females near the southern boundary of recolonization is important to the persistence of residents as well as population expansion. However, nearest habitat to the south is ≥130 km across open land atypical of wolverine habitat. Connectivity between island-like patches of habitat will be critical to continued recolonization, although active restorations may still be needed in areas unlikely to receive females through natural dispersal.

Breeding Season Space Use by Lesser Prairie-Chickens (Tympanuchus Pallidicinctus) Varies Among Ecoregions and Breeding Stages

Abstract: Large-scale declines of grassland ecosystems in the conterminous United States since European settlement have led to substantial loss and fragmentation of lesser prairie-chicken (Tympanuchus pallidicinctus) habitat and decreased their occupied range and population numbers by ∼85%. Breeding season space use is an important component of lesser prairie-chicken conservation, because it could affect both local carrying capacity and population dynamics. Previous estimates of breeding season space use are largely limited to one of the four currently occupied ecoregions, but potential extrinsic drivers of breeding space use, such as landscape fragmentation, vegetation structure and composition, and density of anthropogenic structures, can show large spatial variation. Moreover, habitat needs vary greatly among the lekking/prelaying, nesting, brood-rearing, and postbreeding stages of the breeding season, but space use by female lesser prairie-chickens during these stages remain relatively unclear. We tested whether home range area and daily displacement (the net distance between the first and last location of each day) of female lesser prairie-chickens varied among ecoregions and breeding stages at four study sites in Kansas and Colorado, U.S.A., representing three of the four currently occupied ecoregions. We equipped females with very-high-frequency (VHF) or Global Positioning System (GPS) transmitters, and estimated home range area with kernel density estimators or biased random bridge models, respectively. Across all ecoregions, breeding season home range area averaged 190.4 ha (±19.1 ha se) for birds with VHF and 283.6 ha (±23.1 ha) for birds with GPS transmitters, whereas daily displacement averaged 374.8 m (±14.3 m). Average home range area and daily displacement of bird with GPS transmitters were greater in the Short-Grass Prairie/ Conservation Reserve Program Mosaic and Sand Sagebrush Prairie Ecoregions compared to sites in the Mixed-Grass Prairie Ecoregion. Home range area and daily displacement were greatest during lekking/prelaying and smallest during the brood-rearing stage, when female movements were restricted by mobility of chicks. Ecoregion- and breeding stage-specific estimates of space use by lesser prairie-chickens will help managers determine the spatial configuration of breeding stage-specific habitat on the landscape. Furthermore, ecoregion- and breeding stage-specific estimates are crucial when estimating the amount of breeding habitat needed for lesser prairie-chicken populations to persist.

Habitat use by Long-tailed Weasels in a Fragmented Agricultural Landscape

Abstract: Long-tailed weasels (Mustela frenata) have an extensive North American geographic range and tolerate a wide range of life zones, excluding some desert ecosystems. However, little is known of their habitat use in landscapes fragmented by agriculture, despite the fact that long-tailed weasel populations may be declining in these landscapes. During late winter-spring and late summer-autumn 1998–2000, we monitored 11 long-tailed weasels (seven males, four females) via radio telemetry to examine patterns of habitat use in an Indiana landscape fragmented by agriculture. Long-tailed weasels exhibited scale-dependent patterns of habitat selection (i.e., habitat selection within a landscape and selection of habitats within home ranges). Weasels selected forest patches, fencerows, and drainage ditches, whereas agricultural fields were avoided. Forest patches and fencerows provided suitable den sites and refuge cover from other predators and exhibited an abundant and diverse prey community. Drainage ditches provided movement corridors and access to free-standing, drinking water. The resource selection patterns and limited dispersal ability of long-tailed weasels compared to other carnivores are consistent with the notion that long-tailed weasels appear sensitive to agriculturally induced fragmentation of habitat.