There is an unsettled debate on the benefits of mechanical disturbance for native species in fire-prone habitats. We compared the demographic effects of fire and mechanical treatments (Gyro-tracing) on Polygonella myriophylla, a prostrate clonal shrub listed as endangered and narrowly endemic to pyrogenic scrub ecosystems in south-central Florida. This species is commonly found in gaps within a matrix dominated by resprouting shrubs, but also occurs under other shrubs and along the shoulders of adjacent road-side habitats. We designed and executed a replicated (that plots per treatment, 1 ha per plot; total 147 initial plants) experiment including plots burned, mechanically chopped, with both treatments and without treatments at the Lake Wales Ridge Wildlife and Environmental Area - Carter Creek in Highlands County, central Florida (2005-2008; treated in summer of 2005). Cumulative mortality of standing P. myriophylla after 3 y was higher in burned plots (> 80%) than in chopped-only and untreated plots (∼ 50 % and ∼ 40 % respectively). Post disturbance growth in canopy area among the surviving plants was consistently higher in mechanically disturbed plots compared to untreated plots and intermediate burned conditions. We found three putative seedlings, accounting for less than 3% of the initial genets, before treatment application, but many seedlings after treatments. Seedling recruitment (∼ 90) post-treatment was higher in disturbed plots, highest when both treatments occurred together, and almost null in untreated plots. Recruitment was highest in the first-year post disturbance (70%), decreasing in subsequent years. Disturbances may improve the persistence of P. myriophylla by increasing recruitment and individual growth, however; fire and mechanical disturbance should be used with caution for this species given many plants died during treatment.

Midwestern savannas and woodlands were once dominant transitional communities but are now considered endangered. Savanna and woodland habitat is being restored and managed throughout the central and east-central portions of the United States, but few studies have investigated the effects of management on songbird nest survival. We monitored songbird nests in managed savanna and woodland sites in southern Missouri from 2009 to 2011 to estimate nest survival and to predict the relationships between nest survival and temporal, vegetation structure, and nest site variables. Daily nest survival was generally higher for the four canopy-nesting species, Acadian flycatcher (Empidonax virescens), blue-gray gnatcatcher (Polioptila caerulea), Eastern wood-pewee (Contopus virens), and summer tanager (Piranga rubra) (0.96-0.98), than the four shrub-nesting species, field sparrow (Spizella pusilla), indigo bunting (Passerina cyanea), prairie warbler (Setophaga discolor), and yellow-breasted chat (Icteria virens) (0.92-0.95), for which we estimated survival rates. In general vegetation structure around the nest had little influence on nest survival, except for canopy cover, which occurred in the top model set for four species. Nest survival of yellow-breasted chats was much higher in areas of lower canopy cover, whereas nest survival of Eastern wood-pewees was moderately lower and indigo buntings and summer tanagers peaked at low and intermediate levels of canopy cover, respectively. Therefore, savanna and woodland management, which tends to open the tree canopy, may benefit some bird species in this forested landscape, particularly those associated with low to intermediate canopy cover.

Avian nesting behavior has been correlated with environmental variables and many birds appear to be breeding earlier in response to warming spring temperatures. A primary concern associated with changes in nesting phenology is the potential for ecological asynchrony, whereby avian lifecycle events become out of sync with food resources, potentially leading to avian population declines and decreased opportunities for some birds to suppress pests in agroecosystems. Studies assessing changes in nesting phenology have been conducted at multiple scales and, in many cases, regional assessments allow researchers to pinpoint particular climate variables that impact first egg dates. The objective of this study is to assess the impacts of temperature, precipitation, and growing degree-days (GDD) on first egg dates of Eastern Bluebirds (Sialia sialis) and Tree Swallows (Tachycineta bicolor) across a latitudinal gradient in Ohio. In total we assessed 6535 nesting records submitted through the Cornell Lab of Ornithology's NestWatch Project from 2000-2015. Eastern Bluebirds and Tree Swallows generally nested earlier in areas of lower latitude, although bluebirds in southwest Ohio nested later than birds in central Ohio. Eastern Bluebird first egg dates were earlier in warmer spring (P < 0.001) and both Eastern Bluebird and Tree Swallow first egg dates were later in wetter springs (P < 0.001). Spring temperature did not impact the first egg dates of Tree Swallows (P = 0.89). Tree Swallows first egg dates coincided with greater GDD accumulations than first egg dates of Eastern Bluebirds, and both overlapped key control windows for common insect pests in Ohio. Given climate change predictions in this region in the next century, our results suggest temperature-related first-egg-date advancements may be moderated by nesting delays associated with increased precipitation. Our results also demonstrate a mechanism for using GDD to identify overlaps between the nesting dates of birds and important pest emergence windows in Ohio, which could inform efforts to biologically suppress insect pests.

Grassland habitat in the Northern Prairie region of North America has been greatly reduced since historical times, and conversion to agricultural row-crop production has recently intensified this decline. Common Nighthawk (Chordeiles minor) nesting habitat includes grasslands and flat, gravel rooftops, but relative occurrence of nighthawks in these habitats in the Northern Prairie region has not been previously quantified. We conducted point counts at 396 sites within two study areas in South Dakota, Nebraska, and Iowa; an eastern region dominated by row-crop agriculture and a western region with more grassland within the landscape. We compared land cover at points where nighthawks were present between the two regions and found higher incidences of cropland and grassland in the western region and higher developed land cover in the eastern region. We also compared land cover surrounding points where birds were present vs. absent for both regions combined and found greater cropland around points without birds and greater developed land cover around points with birds. We used Generalized Linear Models (GLMs) with binomial distributions to examine nighthawk presence relative to landscape variables, and ranked models with AICc. In the eastern study region, developed land cover was positively associated with nighthawk presence and cropland showed a weak negative trend with nighthawk presence. Nighthawks in the western region showed a positive association with cropland; suggesting that cropland has a positive effect on nighthawk occurrence, presumably by providing foraging opportunities, if grassland is present within the landscape at sufficient levels. If 2006-2015 regional conversion rates of grasslands and gravel rooftops continue, Markov models project suitable breeding habitat will decrease to levels where nighthawks might be extirpated as breeding birds from urban regions of the Western Corn Belt by 2026 and with substantial population reductions over the entire Northern Prairie region by 2106.

The state of Texas has the highest population of feral hogs, Sus scrofa, than any state in the U.S.A. The expanding abundance and distribution of feral hogs throughout North America is testimony to their ability to adapt to differing environmental and habitat conditions. We evaluated movements and activity of 18 feral hogs fitted with Global Positioning System (GPS) collars between March 2015 through July 2017 in the Texas Panhandle, U.S.A., following three toxicant field studies. We investigated movements of feral hogs in response to individual, weather, and environmental variables using generalized linear mixed models. Nocturnal and diurnal 3 h movements were 753.8 ± 14.28 m and 277.45 ± 8.04 m for all hogs, respectively. Overall mean distance (± se) traveled by feral hogs was 3666.9 ± 64.7 m per day (range: 7.9 to 12985.33 m). Daily distance by males and females averaged 3903.6 ± 112.05 m and 3546.1 ± 78.88 m, respectively, and were not found to be significantly different between sexes. Behavior of feral hogs showed a unimodal pattern, peaking during nocturnal hours. Time of day, land cover type, and temperature were important explanatory variables driving 3 h movements. Sex, temperature, and previous day precipitation were important explanatory variables driving daily distances. Predicting what drives hog movement (e.g., individual and external factors) can allow managers to identify when and where to locate individuals for control efforts, possibly preventing initial invasions by feral hogs.

The red imported fire ant is a well-studied pest in the southern United States, but investigations of invasions in the central region are relatively rare. We compared two central Oklahoma invasions: a newly observed urban invasion on the campus of the University of Central Oklahoma, and an established invasion around Lake Arcadia. We genotyped the General protein-9 (Gp-9) locus to determine social form and eleven microsatellites to evaluate population structure. We hypothesized that colonies were polygyne, that the repeated introductions required to reach central Oklahoma would lead to low genetic diversity, and that the two sites were independently colonized and, therefore, would be genetically isolated. As expected, the analysis of 33 sampled colonies showed that almost all were polygyne and exhibited low genetic diversity, although comparable to diversity found in previous studies. Contrary to our original hypothesis, we discovered that the two separate invasion sites of our study are not differentiated from each other. We found no evidence of distinct genetic clusters within or across sites. However, we did find evidence of two or more introductions that have become integrated. The potential for contemporary gene flow near the northern edge of the fire ant range is concerning as it allows for the maintenance of genetic variation that can lead to more effective adaptation to new environments.

Freshwater mussels play important roles in ecosystems and are globally imperiled. Adult mussels are sedentary and dispersal is as larvae attached to fish hosts and as juveniles in stream drift. Understanding juvenile dispersal is important for understanding the patchy distribution of adult mussels and for conservation. We propose the location in which a juvenile mussel ends up on the streambed is determined by a combination of the juvenile's settling velocity, current speed, and streambed topography. We conducted a laboratory experiment to quantify the settling velocities of juveniles of four mussel species and of polymer microparticles, later utilized as surrogates for juveniles. We performed a flume experiment where we measured drift distances of microparticles at three low flow velocities over gravel and over a simulated mussel bed (gravel combined with mussel shells). Lastly, we measured drift distances of microparticles at five sites in two small rivers under summer low flow conditions. There were no significant differences in settling velocities among the four mussel species, live juveniles sank at a significantly lower rate than dead juveniles, and there were no significant differences in settling velocities between live juveniles and microparticles. The distances microparticles drifted in the flume increased with flow velocity and were shorter over the simulated mussel bed than over gravel. In the field most microparticles were recaptured near their release locations. In this study, juvenile mussels had limited dispersal potential with most drifting < 10 m. This limited dispersal should result in many juveniles settling within mussel beds, areas where habitat conditions are favorable for survival and growth, and may contribute to the patchy spatial distribution of mussel beds in rivers.

Redside dace Clinostomus elongatus in Minnesota represent genetically unique peripheral populations on the extreme western edge of their native range with uncertain population status. Electrofishing surveys were conducted in 2017 in the Little Cannon River watershed to ascertain life history traits (e.g., age, growth, reproductive traits) for comparison to core populations in eastern North America and to assess population status. Minnesota redside dace grew faster but lived shorter lives than their core populations/counterparts. Females matured at age-2 and about 80 mm total length and males at age-1 and 70 mm. Females produced up to 962 eggs. Estimated population size for age 1 dace was 9251 (95% C.I. 8300–10,201) and for age 2 was 6600 (95% C.I. 5789–7411). These values exceeded a demographic minimum viable population estimate of 3305 (nearly double) suggesting that redside dace should persist in this watershed for at least the next two decades (until ≈ 2040).

Round goby (Neogobius melanostomus) are invasive benthic fish native to the Black and Caspian Seas of Eurasia. First documented in the Chicago Area Waterway System in 1993, this aggressive species has been progressing from Lake Michigan toward the Mississippi River via the Illinois River. Here we describe the history of round goby monitoring in the Illinois River and the more recent annual efforts by the U.S. Fish and Wildlife Service to document the expansion of round goby toward the Mississippi River using multiple gears. From 2014 to 2017, annual monitoring has documented the expansion of round goby in the lower Illinois River to within 55 rkm of the Mississippi River, beyond previously published capture locations. Although it is unclear whether or not round goby are reproducing this close to the Mississippi River or if a population is established, their presence is concerning considering their deleterious impacts to native species in other systems. Additionally, the Mississippi River and its tributaries provide an abundance of preferred spawning habitats that could facilitate the expansion of self-sustaining populations throughout the Upper Mississippi River watershed. We urge the development of more robust monitoring and management strategies designed to identify and mitigate the potential impacts of this species.

The headwaters of the Susquehanna River are contained within the Otsego Lake catchment in central New York and are home to members of the aquatic neuropteran family Sisyridae, which are predators/parasites of freshwater sponges as larvae. This study used cytochrome oxidase I (COI) barcoding to identify the neuropteran taxa present on freshwater sponges and both spicule morphology and COI to identify sponge species in the Otsego Lake watershed. Both Climacia areolaris (Hagen, 1861) and Sisyra vicaria (Walker, 1853) were identified from a tributary to Otsego Lake and within the main branch of the Susquehanna River, while multiple sponge species were identified from the watershed. These are the first records of sisyrids from the Otsego Lake watershed and Climacia areolaris from Otsego County, New York.

The potential for arbuscular mycorrhizal (AM) fungi to confer resistance and provide bioprotection against plant pests and pathogens is intriguing to biologists studying at many levels of biological organization, including the organismal, population, and community levels. In recent years, there has been a growing trend to experimentally test the role of AM-fungi in plant-enemy performance. Yet, it remains unclear whether taxon usage in these studies are biasing the results. Here I conducted a survey, while strictly focusing on the effect of AM-fungi, with respect to plant-enemies performance. I found 25% of case studies did not observe a reduction in performance. Interestingly, 75% of studies featured a single AM-fungal taxon, as opposed to multiple taxa. What is even more compelling, 72% of studies featured Rhizophagus irregularis and Funnelformis mosseae. These findings demonstrate a lack of AM-fungal diversity in this area of research and a need for expansion in mycorrhizal taxon usage, to understand more fully the significance of mycorrhizal application in conferring bioprotection.

The Osage orange (Maclura pomifera) is considered anachronistic because it has no known seed disperser. However, anecdotal observations suggest squirrels (Sciurus spp.) may act as dispersers as they move fruits away from parent plants and through the prolonged handling time required to access the seeds. Our aim was to determine if squirrels potentially disperse Osage orange seeds in this manner by presenting Osage orange seeds and fruits in the presence and absence of sunflower seeds (whole and shelled), which squirrels are known to consume readily. We found, although squirrels preferred sunflower seeds, they readily consumed the Osage orange seeds and moved the fruits when multiple food sources were available. However, when fruits were presented alone, we found a small number of fruits were moved and these were moved only a short distance. Our results suggest that while squirrels occasionally show interest in Osage orange fruits, they do not typically disperse M. pomifera seeds via fruit handling. We therefore conclude anecdotal observations of squirrels feeding on seeds represent uncommon events, supporting the hypothesis that M. pomifera is anachronistic.