Ameiva corvina

Number of Pages: 2Integrative BiologyGeological Science

A Classic Question Revisited in Red-winged Blackbirds: Disentangling Confounding Hypotheses Surrounding Parental Investment Theory and Nest Defense Intensity

The pattern of increased nest-defense effort over the course of a nesting season could result from 3 distinct (albeit non-exclusive) mechanisms: increased value of offspring to parents with progression towards independence (parental-investment theory), decreased opportunity for renesting (renesting-potential hypothesis), or decreased perceived costs of defense after repeated encounters with human observers (positive-reinforcement hypothesis). To gauge relative empirical support for each of these mechanisms, we disentangle these 3 often-confounded hypotheses using multi-model inference with mixed-model ordinal regression applied to an extensive red-winged blackbird (Agelaius phoeniceus) nesting data set (4,518 monitoring visits to 1,330 nests). Parent aggression was rated on an ordinal scale (0-4) during repeated monitoring visits. Additionally, we assessed clutch/brood size, nest density, time of day, and nest concealment effects on aggression. In a preliminary analysis, including all 3 major hypotheses, male and female nest defense was most strongly explained by parental investment (nest age). Positive-reinforcement (visit number) and renesting potential (Julian date), were also well-supported predictors in males. The interactions of decomposed nest age (within- and between individual centered) with Julian date were particularly important in the top male model. Additional factors, such as clutch/brood size, nest density, and nest concealment appeared to have larger predictive roles in explaining female aggression relative to males. These patterns are likely explained by different sexual reproductive roles within a polygynous mating system. Our study highlights the importance of interacting mechanisms involving parental investment theory and the use of within-individual standardization to help disentangle competing, and empirically confounded hypotheses

Spatial Ecology and Habitat Use of the Western Fox Snake (Elaphe Vulpina Vulpina) on Squaw Creek National Wildlife Refuge

The western fox snake (Elaphe vulpina vulpina) is endangered in the state of MIssouri, occupying only the northern corner of the state. I investigated the spatial ecology and habitat use of this snake on Squaw Creek National Wildlife Refuge using radio telemetry. A total of 21 snakes were tracked during a portion of the 2003 active season. Snake locations were recorded with GPS units and plotted into a GIS program. At each snake location and 207 random sites for comparison, 29 microhabitat variables were measured. There were no general gender or seasonal gender differences in activity measures. Linear migrations were observed in several male snakes between hibernacula and summer feeding grounds. Females made long migrations (1259 ± 241 SE m) to suspected oviposition sites. Snake home ranges (37.55 ± 8.93 SE ha, 100% MCP) included all tracking points, and snakes traveled at a mean daily speed of 47.39 ± 4.12 SE (m/day). Snakes were commonly associated with lowland rather than upland habitat subunits, with wet prairies and managed wetlands having the highest proportions, respectively. Use of habitat subunits was individually variable and collectively-nonrandom. Wet prairies were used significantly more than expected whereas bottomland forests were generally avoided. Habitat centroids significantly differed between groups (male, female, and random locations) and in subsequent pairwise comparisons. Male and female snakes typically were found in denser-taller vegetation and taller-coverage dead vegetation than random sites. Only 2 of 21 snakes were tracked to known hibernacula due to loss of transmitter signal, or mortality (depredation and human activity)

American Crow Caches Rabbit Kits

Volume: 118Start Page: 572End Page: 57

EFFECTS OF SCALE AND HABITAT MANAGEMENT ON GRASSLAND BIRD RESPONSE IN CONSERVATION RESERVE PROGRAM FIELDS IN NORTHWEST ILLINOIS

North American populations of grassland birds have been declining consistently for the past several decades. Grassland birds respond to multiple scales which encompass a spectrum of habitat variables, and the habitat scale of importance may depend on the response of interest. For practitioners, having knowledge of the effect of scale is useful because conservation efforts can be focused at the most appropriate scale. However, previous multi-scale studies of grassland birds and other taxa have rarely incorporated on-the-ground habitat management while simultaneously investigating site-specific species turnover dynamics (Chapter 1) and daily nest survival (Chapter 2). Also, habitat management-related studies often suffer when not accounting for inherent variation between fields, field landscapes, and study year; thus, to disentangle specific effects of management, it is important to account for this variation by using these factors as random effects within mixed-effects models (Chapter 3). Understanding multi-scale habitat relationships affecting site turnover, also known as dynamic occupancy, and daily nest survival rate (nest survival or DSR), as well as how multiple avian responses vary with grassland management would further benefit conservation decision making for focal species. I investigated dynamic occupancy and nest survival of both obligate and facultative grassland species relative to multi-scale habitat factors on private lands (Conservation Reserve Program) in northwest Illinois during 2011-2014. I also conducted a separate analysis focusing on how multiple avian responses, ranging from species presence/absence (P/A) to species-specific nest survival, are influenced by non-fire grassland management treatments. For dynamic occupancy, a combination of ≥2 scales always outperformed single-scale models for all species. Three of 7 species responded to either cumulative habitat management (proportion of field managed over the study period) or yearly management (33% of field managed before a particular breeding season) regardless of dominant grass type. Of the 48 covariates appearing in top models across species for both dynamic and single-season occupancy, microhabitat covariates (42%) were represented most often, followed by patch-scale (33%) and landscape-scale (25%) factors. Covariates with the most consistent effects and the greatest frequencies appearing in competitive (∆AIC ≤ 4) dynamic and single-season occupancy models included landscape forest cover (n = 10), surrounding patch grassland cover (n = 7), and field size (n = 6). In general, increasing levels of forest cover adjoining fields had consistently negative effects on occupancy, colonization, and persistence across species, while grassland surrounding fields and field size had positive effects on these responses. Microhabitat covariates better explained colonization and extinction across the focal species. Of the 22 habitat covariates in top colonization and extinction models, microhabitat variables were represented 50% of the time, compared to 32% and 18% representation for patch-scale and landscape-scale covariates, respectively. I recommend that wildlife biologists utilize habitat management techniques to ensure grassland birds have different successional stages within their range of preferences. My results suggest that grassland disturbance, while influencing turnover dynamics of different species, may be less influential within smaller fields and landscapes dominated by forest cover. I analyzed the daily nest survival rate for 2 species (red-winged blackbirds and dickcissels) and 2 groups of nesting communities (ground and above-ground nesters). Temporal variables such as Julian date and stage of nest were significant predictors of nest survival for red-wings (50.58 ∆AICc = best temporal model) and dickcissels (2.28 ∆AICc = best temporal model) in addition to habitat covariates. In 3 of 4 analyses ≥2 habitat scales were better predictors of nest survival over one scale. For ground nesters the patch scale was be best predictor of nest survival. However, the best model for ground nesters did not have overwhelming support compared to the random model (1.43 ∆AICc). The ground-nesting community appeared to suffer decreased nest survival with increasing proportion of surrounding grassland. The blackbird top model included nest- and landscape-scale covariates, and top models for dickcissels and the above-ground nesting community included the nest- and patch-scale covariates. Blackbirds had a significant increase in nest survival when nests were placed in areas with higher vegetation density and height (greater visual obstruction). Comparatively, the predictive ability of habitat covariates was not as strong for the other 3 analyses; however, notable patterns include dickcissel nest survival decreasing with increasing nest distance to edge and above-ground nests had increased nest survival with increasing patch perimeter-area-ratio. My results suggest different species are responding to different scales, but finer-scale habitat covariates generally help predict nest survival over course-scale habitat features, such as landscape covariates. Songbird nest survival maybe more influenced by fine-scale habitat characteristics such as nesting cover and field vegetation complexity and density, which can deter nest predators and reduce their search efficiency. In a way, this is positive news for practitioners working in grasslands patches located in less than ideal patch or landscape configurations, suggesting more effort could be focused on improving conditions for colonization and persistence of focal species (Chapter 1). By focusing management on dynamic occupancy responses, increasing potential nesting habitat and territory quality for focal species will likely follow. When investigating multiple avian responses to management, within a consistent mixed-effect modeling framework, it appeared that avian survey related responses were best supported, having consistently larger ∆AICc values for top models, when compared to nesting-related data. One explanation of this relative difference could be attributed sample size difference between analyses. Focusing on the effects of management, this analysis accounted for inherent variation across fields, year, and potentially field landscape, as random effects within all models. As suggested from Chapter 2, and despite a large sample of nests, explanation of DSR across all species and focal species showed little improvement with management covariates. Brome fields cumulatively managed with spray or spray/seed treatments (Chapter 1) appeared to respond most and likely explained general positive effects for red-winged blackbird and dickcissel abundance; however, this was at a cost to species abundance for bobolink (Dolichonyx oryzivorus), Henslow’s sparrow (Ammodramus henslowii), eastern meadowlark (Sturnella magna), field sparrow (Spizella pusilla), and northern bobwhites (Colinus virginianus), due to the release of tall forbs within the seed bank after spraying brome dominated fields. Dramatic vegetation responses in sprayed brome fields likely led to an overall decrease in obligate-grassland bird richness and conservation value on brome field types that were cumulatively management over the course of the study. These results suggest the importance of non-native brome CRP fields for certain grassland-obligate bird species, while also revealing the apparent decoupling of nest survival and other avian responses measured commonly. I suggest managers and researchers pay closer attention to variables affecting nesting abundance/density in grassland systems when possible and recognize the potential importance of non-native grasses for grassland-obligate birds in some regions

Shew_et_al_2018_Journal_of_Applied_Ecology

Data package includes: README, text R script, and data files used to analyze daily nest survival of grassland birds in northwestern, Illinois, USA (2011-2014) associated with Conservation Reserve Program management and multi-scale factors

Data from: Finer-scale habitat predicts nest survival in grassland birds more than management and landscape: a multi-scale perspective

1. Birds may respond to habitat at multiple scales, ranging from microhabitat structure to landscape composition. North American grassland bird distributions predominantly reside on private lands, and populations have been consistently declining. Many of these lands are enrolled in U.S. federal conservation programmes, and properly guided management policies could alleviate declines. However, more evaluative research is needed on the effects of management policies juxtaposed with other multi-scale habitat features. Furthermore, research focused on nest survival is arguably more valuable because habitat associations with avian densities can sometimes be deceptive. 2. We investigated nest survival of a grassland facultative (red-winged blackbird, Agelaius phoeniceus) an obligate species (dickcissel, Spiza americana), and two nesting communities (ground and above-ground nesters) relative to management and multi-scale habitat (nest-site characteristics, in-field microhabitat, patch metrics, and landscape context). Our study was conducted on private lands in Illinois (2011-2014) and directly linked to policy-based management (disking, herbicidal spraying, spray/interseeding) and landowner decisions. 3. Multi-scale models explained more variation in nest survival compared to single scales or management in three of four analyses (blackbirds, dickcissels, and above-ground nesters). Finer-scale habitat variables, such as nest-site characteristics, were more often in top and among the competitive models relative to landscape factors. 4. Compared with other management types, disking (i.e. tractor-pulled disc harrows removed approximately 50% of vegetation) displayed distinct effects and positively influenced nest survival in above-ground nesters. Also, greater proportions of a field managed cumulatively and yearly, regardless of type, generally improved nest survival for dickcissels and above-ground nesters. All groups except above-ground nesters had generally higher nest survival in native grass fields. 5. Synthesis and applications. Habitat practitioners can improve nest survival for certain grassland birds by directly affecting infield-microhabitat vegetation and structure. However, characteristics associated with specific nest locations often drive nest survival. We suggest habitat managers and agency staff promote native grass practices and management, such as disking, to enhance nest survival of grassland bird populations. Management will likely be most effective in favourable unfragmented grassland landscapes with less surrounding forested areas, which also promote other important responses (e.g. colonization and persistence) of target species

Crop Residue burning from high-resolution satellite imagery and PM2.5 dispersion: A case study of Mississippi County, Arkansas, USA

ABSTRACTCrop residue burns typically result in particulate matter (PM2.5), methane (CH4), carbon monoxide (CO), nitrous oxide (N2O), nitrogen oxides (NOx), volatile organic carbon (VOC), and black carbon emissions, which affect air quality and can pose a risk to public health. Currently, Arkansas farmers self-regulate crop burning using voluntary smoke management guidelines to reduce community impacts from smoke by ensuring burns take place in optimal conditions. The aim of this study is to identify burned cropland areas and examine human-caused fire PM2.5 emissions and dispersion during optimal burn conditions, specifically within Mississippi County, Arkansas, USA, using two separate methods. During the 2019 harvest season, high-resolution satellite data was used to manually identify burned areas and crop types. The total cumulative cropland burned area in 2019 was estimated to be 7,137 acres (29.03 km2). Burning harvested rice fields accounted for approximately 35% of the total annual PM2.5 emissions from all annual agricultural burning as reported in the 2017 U.S. EPA National Emissions Inventory, while PM2.5 emissions from burning corn fields were only 8% of the total estimated annual PM2.5 emissions. Approximately 43% of annual agricultural burning PM2.5 emissions occurred between 15 August and 23 October in Mississippi County. These high-resolution burned areas were not captured in the standard coarse resolution active fire products. Secondly, during the 2020 fall harvest season, we measured PM2.5 emissions using a Purple Air sensor and modeled smoke dispersion from a planned burn of rice fields following state-level voluntary guidelines. Additionally, the smoke transport model HYSPLIT was deployed to model this planned burn. The HYSPLIT results suggest that smoke disperses into the atmosphere from burns following the guidelines, limiting ground-level human exposure under optimal burning conditions.Implications: Fire has long been used as a cropland management tool to control weeds and invasive species and remove residues between crop rotations. Residue burns produce emissions that can present public health concerns. This study presents a novel attempt to quantify cropland burning with satellite imagery, estimate emission inventories by crop type, and simulate particulate matter dispersion from in-field burns. The results of this two-phase analysis show that our understanding and quantification of human-caused cropland burning and emissions can still be improved and integrated into management approaches as well as emission inventories

The need for early Kasai portoenterostomy: a Western Pediatric Surgery Research Consortium study

PurposeThe purpose of this study was to investigate factors impacting transplant-free survival among infants with biliary atresia.MethodsA multi-institutional, retrospective cohort study was performed at nine tertiary-level children's hospitals in the United States. Infants who underwent Kasai portoenterostomy (KP) from January 2009 to May 2017 were identified. Clinical characteristics included age at time of KP, steroid use, surgical approach, liver pathology, and surgeon experience. Likelihood of transplant-free survival (TFS) was evaluated using logistic regression, adjusting for patient and surgeon-level factors. Secondary outcomes at 1 year included readmission, cholangitis, reoperation, mortality, and biliary clearance.ResultsOverall, 223 infants underwent KP, and 91 (40.8%) survived with their native liver. Mean age at surgery was 63.9 days (± 24.7 days). At 1 year, 78.5% experienced readmission, 56.9% developed cholangitis, 3.8% had a surgical revision, and 5 died. Biliary clearance at 3 months was achieved in 76.6%. Controlling for patient and surgeon-level factors, each additional day of age toward operation was associated with a 2% decrease in likelihood of TFS (OR 0.98, 95% CI 0.97-0.99).ConclusionEarlier surgical intervention by Kasai portoenterostomy at tertiary-level centers significantly increases likelihood for TFS. Policy-level interventions to facilitate early screening and surgical referral for infants with biliary atresia are warranted to improve outcomes