Food Habits of the Hoary Bat in an Agricultural Landscape

Information on diets is fundamental to ecological studies. Prey use by the solitary, tree-roosting hoary bat (Lasiurus cinereus) in agricultural landscapes is not known. We examined the stomach contents and fecal material from carcasses of hoary bats collected during a mortality study at wind turbine sites in southwestern Minnesota. We compared diet of hoary bats to availability of prey to determine whether bats were opportunistic or selective. Food of the hoary bats primarily consisted of lepidopterans (moths; 49-50 %) and coleopterans (beetles; 28-40 %). The abundance of insects in the diet of hoary bats was not proportional to the estimated availability of prey. Hoary bats selected large, soft-bodied insects (e.g., lepidopterans and neuropterans) and avoided small or hard-bodied insects (e.g., coleopterans, dipterans, and hemipterans). We suggest that hoary bats do not select prey based on availability, but rather, select prey that are large and soft-bodied

Factors Influencing Persistence of White-footed Mice

We examined factors that potentially influenced persistence of the white-footed mouse (Peromyscus leucopus) during 1981 to 1988 at Konza Prairie Biological Station, Kansas. We predicted that both abiotic (e.g., precipitation and temperature) and biotic (e.g., availability of food and density of conspecifics) factors would influence persisten~e of individuals at the study site. Persistence of individual white-footed mice on the study site differed among years and seasons. White-footed mice that were first captured in summer or in autumn persisted longer than those first captured in spring. Young females (less than 20 g) had greater persistence than young males, whereas old males (greater than or equal to 25 g) had greater persistence than old females. Persistence of white-footed mice captured in summer, autumn, and spring was related to abundance of white-footed mice, to production of seeds by woody plants, and to precipitation during MarchMay, respectively. Ambient temperature had no influence on persistence. We suggest that biotic and abiotic factors that influence persistence of white-footed mice are local in scale and that they affect persistence differentially at different times of the year

Food Habits of Dabbling Ducks During Fall Migration in a Prairie Pothole System, Heron Lake, Minnesota

We conducted an analysis of dabbling duck food habits in the fall of 2002 and 2003 in the Heron Lake system. Gizzard contents of hunter-harvested birds were analyzed using the percent aggregate volume method to determine what food items were consumed and in what quantity. Curltop Ladysthumb (Polygonum lapathifolium) was the food item consumed most often (82.2%) and in the greatest volume (34.2 ml). Sago Pondweed (Stuckenia pectinata) was the only food item of which multiple plant parts were consumed. However, the seeds and tubers only comprised 1.27 and 0.07 of the total aggregate percent

Nonnative Ungulate Impacts on Greater Sage-grouse Late Brood-rearing Habitat in the Great Basin, USA

Domestic livestock grazing is the dominant land use on much of the current range inhabited by greater sage-grouse (Centrocercus urophasianus; sage-grouse) in the western United States. Nonnative feral horses (Equus ferus caballus) also inhabit important sage-grouse seasonal habitats. Overabundant feral horse populations and improper grazing by domestic cattle (Bos taurus) can impact the health of sagebrush (Artemisia spp.) and desert shrub rangeland communities and native wildlife. These impacts to sage-grouse can be exacerbated when they affect late brood-rearing habitat, which provide the forbs and arthropods required to fledge broods. Managers require better information regarding the extent of these impacts. In 2020, we assessed the potential impact of feral horses and domestic cattle on sage-grouse late brood-rearing habitats in western Utah and eastern Nevada, USA. We acquired late brood-rearing location data from sage-grouse marked with global positioning system and very-high frequency radio-transmitters from 2016 to 2020 for North Utah data, 2017 to 2018 for South Utah data, and 1961 to 2017 for both east and west Nevada data to delineate late brood-rearing habitats. Using these location data, we compared 8 sites (4 pairs) within horse and non-horse use areas to assess sage-grouse habitat quality characteristics between areas that have been predominantly horse and cattle grazed versus sites that have been predominantly cattle grazed. For each pairing, 1 site was located within and the other outside of a Bureau of Land Management herd management area boundary, and both sites shared similar habitat characteristics (i.e., topography, dominant vegetation, soils, and climate) and selection probability for broods. We collected vegetation and dung count data at each site to assess characteristics related to habitat quality for sage-grouse brood-rearing, based on ungulate presence. We used a mixed model analysis of variance to detect differences between each paired site comparison (α \u3c 0.01). Horses or evidence of horse presence (i.e., dung) were not detected at our non-horse sites allowing for an unbiased comparison between paired sites. Cattle presence was noted at all our paired sites. Average annual grass frequency was 0.74 in horse and 0.17 in non-horse use areas (P = 0.20), and average annual grass cover was 4.0% compared to 0.2% in horse use areas (P = 0.32). Average annual grass biomass was 0.45 kg/ha in horse and 0.04% in non-horse use areas (P = 0.34). Vegetation height was 44.2 cm in non-horse compared to 34.5 cm in horse use areas (P = 0.23). These results suggest that increased ungulate grazing and year-long use of late brood-rearing habitat by feral horses coupled with livestock grazing may impair habitat suitability, particularly considering ecological impacts from invasive plant species. Our results suggest that managing late brood-rearing habitats to reduce the frequency and intensity of year-long grazing by feral horses can be best accomplished by reducing horse numbers and the seasonal distribution of grazing by domestic livestock

N-body simulations of gravitational dynamics

We describe the astrophysical and numerical basis of N-body simulations, both of collisional stellar systems (dense star clusters and galactic centres) and collisionless stellar dynamics (galaxies and large-scale structure). We explain and discuss the state-of-the-art algorithms used for these quite different regimes, attempt to give a fair critique, and point out possible directions of future improvement and development. We briefly touch upon the history of N-body simulations and their most important results.Comment: invited review (28 pages), to appear in European Physics Journal Plu

Artificial Nightlight Alters the Predator–Prey Dynamics of an Apex Carnivore

Artificial nightlight is increasingly recognized as an important environmental disturbance that influences the habitats and fitness of numerous species. However, its effects on wide‐ranging vertebrates and their interactions remain unclear. Light pollution has the potential to amplify land‐use change, and as such, answering the question of how this sensory stimulant affects behavior and habitat use of species valued for their ecological roles and economic impacts is critical for conservation and land‐use planning. Here, we combined satellite‐derived estimates of light pollution, with GPS‐data from cougars Puma concolor (n = 56), mule deer Odocoileus hemionus (n = 263) and locations of cougar‐killed deer (n = 1562 carcasses), to assess the effects of light exposure on mammal behavior and predator–prey relationships across wildland–urban gradients in the southwestern United States. Our results indicate that deer used the anthropogenic environments to access forage and were more active at night than their wildland conspecifics. Despite higher nightlight levels, cougars killed deer at the wildland–urban interface, but hunted them in the relatively darkest locations. Light had the greatest effect of all covariates on where cougars killed deer at the wildland–urban interface. Both species exhibited functional responses to light pollution at fine scales; individual cougars and deer with less light exposure increasingly avoided illuminated areas when exposed to greater radiance, whereas deer living in the wildland–urban interface selected elevated light levels. We conclude that integrating estimates of light pollution into ecological studies provides crucial insights into how the dynamic human footprint can alter animal behavior and ecosystem function across spatial scales

Prenatal Diagnosis of Oculocutaneous Albinism by Electron Microscopy of Fetal Skin

Oculocutaneous albinism was diagnosed prenatally by electron microscopic examination of fetal skin samples taken during fetoscopy at 20 weeks of gestation. Melanosome development in hair bulb melanocytes progressed no further than stage II, indicating a lack of melanin synthesis. In 4 age-matched control fetuses, numerous stage IV melanosomes, signifying active melanin synthesis, were identified. The diagnosis was confirmed after the pregnancy was terminated at 22 weeks. Examination of the fetal eye showed absence of pigment in the retinal epithelium and uvea at a stage when ocular melanogenesis would normally be active. This study shows that oculocutaneous albinism can be detected in the second trimester using similar techniques to those employed in the prenatal diagnosis of epidermolysis bullosa and ichthyosis

Testing the priority-of-access model in a seasonally breeding primate species

In mammals, when females are clumped in space, male access to receptive females is usually determined by a dominance hierarchy based on fighting ability. In polygynandrous primates, as opposed to most mammalian species, the strength of the relationship between male social status and reproductive success varies greatly. It has been proposed that the degree to which paternity is determined by male rank decreases with increasing female reproductive synchrony. The priority-of-access model (PoA) predicts male reproductive success based on female synchrony and male dominance rank. To date, most tests of the PoA using paternity data involved nonseasonally breeding species. Here, we examine whether the PoA explains the relatively low reproductive skew in relation to dominance rank reported in the rhesus macaque, a strictly seasonal species. We collected behavioral, genetic, and hormonal data on one group of the free-ranging population on Cayo Santiago (Puerto Rico) for 2 years. The PoA correctly predicted the steepness of male reproductive skew, but not its relationship to male dominance: the most successful sire, fathering one third of the infants, was high but not top ranking. In contrast, mating success was not significantly skewed, suggesting that other mechanisms than social status contributed to male reproductive success. Dominance may be less important for paternity in rhesus macaques than in other primate species because it is reached through queuing rather than contest, leading to alpha males not necessarily being the strongest or most attractive male. More work is needed to fully elucidate the mechanisms determining paternity in rhesus macaques

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks