Regulated power supply Patent

Design, development, and operating principles of power supply with starting circuit which is independent of voltage regulato

Review: NORTH AMERICAN DUCKS, GEESE & SWANS: IDENTIFICATION GUIDE. Frank S. Todd.

The North American Duck, Geese & Swans: Identification Guide, released in 2018, is the culmination of a lifetime of waterfowl photography by the late Frank Todd. Indeed, this book stands apart from other identification guides as being entirely photo-driven, with minimal introductory material, notations of field marks, or descriptions of the various waterfowl species. It is small enough to be carried in the field (6.5” × 9” × 0.5”), but most readers will find it less useful than a standard bird identification book (Sibley 2014), even for waterfowl. As the title suggests, the Todd guide focuses on North American species, but also includes an opportunistic sample of some vagrants. The sheer number of photographs is impressive (even overwhelming at times), and this guide would make a colorful addition to the libraries of amateur waterfowl enthusiasts across North America. The book format is straightforward: each group of birds (e.g., dabbling ducks, sea ducks) begins with a conversational paragraph that provides an entry-level description of basic life history and behavior. Within taxonomic groupings, each species that follows is allotted 1–3 pages with a small range map, one line of morphological measurements, four bullet points of identification tips, and an estimated North American population size that sometimes includes worldwide estimates. The overwhelming majority of each species account is composed of 5–45 photos of the bird in question. Interestingly, the photos themselves have been clipped to silhouettes in photo-editing software, i.e., ducks are “floating” on a monochromatic page rather than swimming on the water or flying through the air as they were in the original photograph. This cropping method is similar to that used in the Crossley ID Guide: Waterfowl, but Crossley et al. (2017) set collages of clipped photographs into a realistic photo backdrop to highlight the habitat in which species are commonly observed

Vegetation phenology and nest survival: Diagnosing heterogeneous effects through time

bias; duck; grassland; mallard; prairie; Robel; waterfowl; WATERFOWL PRODUCTION; HABITAT SELECTION; ARTIFICIAL NESTS; MOTTLED DUCKS; WINTER-WHEAT; SUCCESS; NORTH; PREDATION; CONCEALMENT; FIELD

Cover Use and Activity Time Budget of Blue-Winged Teal, Mallard, and Pintail Broods

Blue-winged teal (Anas discors), mallard (A. platyrhynchos), and pintail (A. acuta) broods were observed on 17 days between 25 June and 30 July, 1976. Brood activities and cover uses were recorded continuously from first light until dark. Observations of 269 broods from three wetlands were evaluated by species and brood age-class. Activity time budgets revealed significant (p\u3c.01) age specific differences in total feeding time and visibility among age-classes of all species combined and age-classes of blue-winged teal broods. Feeding modes also varied among age-classes. Daily patterns of cover use varied among brood age-classes and species. Morning and evening feeding peaks became more pronounced, and overall visibility increased, with brood age. Interspecific differences in daily activity patterns were observed among broods of the same age-class. Duration of active periods increased with age in blue-winged teal broods. Active periods recurred at regular intervals in all broods throughout the day, suggestive of polycyclic behavior patterns similar to those of adult ducks. A progressive increase in brood visibility was attributed primarily to seasonal changes in brood age structure and to wetland water loss. Temperature and wind speed influenced brood visibility during most observation days. Climatic conditions favorable to nighttime brood activity influenced brood behavior during the following day. Accuracy of present brood inventory techniques could be improved if considerations were made for brood behavior patterns and environmental factors which alter brood cover use

Louisiana Black-bellied Whistling-Duck clutch characteristics in the presence of conspecific and interspecific brood parasitism

Black-bellied Whistling-Ducks (Dendrocygna autumnalis; Whistling-Duck) are undergoing a rapid range expansion northward and now breed throughout the Southeastern United States. As a facultative cavity-nesting species, they have the potential to compete with Wood Ducks (Aix sponsa) and Hooded Mergansers (Lophodytes cucullatus) for nest sites. Little is known about Whistling-Duck breeding biology, and estimates of clutch characteristics and rates of conspecific and interspecific brood parasitism (CBP and IBP, respectively) are lacking. We monitored Whistling-Duck nests in Louisiana to describe nesting chronology, clutch size of parasitized and unparasitized (normal) nests, and hatchability (i.e., the portion of eggs that hatched) for clutches of different sizes and types. We monitored a total of 558 nest boxes between 2020–2021 and determined the presence of brood parasitism for 231 Whistling-Duck nests. CBP was detected in 73 (31.6%) nests, and IBP was observed in 51 (22.1%) nests parasitized by Wood Ducks, two (0.9%) nests parasitized by Hooded Mergansers, and one nest contained eggs from all three species. Normal clutches were smaller (15.4 ± 4.4 eggs) than CBP clutches (26.1 ± 8.8 eggs) and mixed clutches (22.2 ± 5.3 eggs; clutches containing Wood Duck or Hooded Merganser eggs; all pairwise P \u3c 0.0001). However, within clutch repeatability, estimates for egg morphology data (i.e., length, width, and mass) were low (\u3c 0.40) for normal clutches, suggesting CBP went undetected. Of 180 fated nests used to determine hatchability, 66 (36.7%) were successful, 49 (27.2%) were abandoned, 64 (35.6%) were depredated, and one (0.6%) was nonviable. Considering successful nests, hatchability was high for all clutch size bins ranging from 67.4% (41–45 eggs) to 81.6% (11–15 eggs). Our study is the first to document Whistling-Ducks successfully hatching mixed-species broods, and such high productivity could be contributing to Whistling-Duck range expansion

Subsampling reduces sorting effort for waterfowl foods in salt-marsh core samples

Waterfowl researchers often use soil core samples to estimate food availability in foraging habitats, and these estimates are needed for bioenergetic models of carrying capacity. However, core sampling is frequently a time-and resource-intensive process, and some researchers have suggested that subsampling may be a valuable way to reduce processing time. We evaluated whether 10% and 25% by mass subsampling are appropriate techniques for reducing core-sorting effort while maintaining precision for samples taken in six separate habitat types along the Delaware bayshore. We found no significant difference between biomass found in 100% sorted cores and estimated biomass obtained by 10% and 25% subsampling. We found that 10% subsampling offered the greatest time savings, reducing mean sorting times by 77% (from 13.7 hours to 3.3 hours) from 100% sorted cores. We recommend that researchers consider subsampling to reduce core-sorting effort and cost, particularly when processing large numbers of cores

Assessing uncertainty in coastal marsh core sampling for waterfowl foods

Quantifying foraging resources available to waterfowl in different habitat types is important for estimating energetic carrying capacity. To accomplish this, most studies collect soil-core samples from the marsh substrate, sieve and sort food items, and extrapolate energy values to wetland or landscape scales. This is a costly and time-intensive process; furthermore, extrapolation methods yield energy estimates with large variances relative to the mean. From both research and management perspectives, it is important to understand sources of this variation and estimate the number of soil cores needed to reduce the variance to desired levels. Using 2,341 cores collected from freshwater and salt marsh habitats at four sites along the Atlantic Coast, we examined sampling variation and biological variation among sites and habitats. When we removed extreme outliers in the data caused by large animal food items found in a small core sample, estimates of energy density decreased by an order of magnitude for most habitats. After removing outliers, we found inconsistent geographical variation among habitat types that was especially pronounced in freshwater and no evidence for within-season temporal depletion of food resources for any site or habitat. We used a Monte Carlo simulation approach to estimate the optimal number of cores (minimizing both cost and estimated variance) sampled in each habitat type. Across most contexts, a reduction in the coefficient of variation reached diminishing returns near 40 core samples. We recommend that researchers explicitly address outliers in the data and managers acknowledge the imprecision that can arise from including or excluding outliers when estimating energy density at landscape scales. Our results suggest that collecting 40–50 cores per habitat type was sufficient to reduce the variance to acceptable levels while minimizing overall sampling costs

Time to fly: A comparison of marginal value theorem approximations in an agent-based model of foraging waterfowl

One of the fundamental decisions foragers face is how long an individual should remain in a given foraging location. Typical approaches to modeling this decision are based on the marginal value theorem. However, direct application of this theory would require omniscience regarding food availability. Even with complete knowledge of the environment, foraging with intraspecific competition requires resolution of simultaneous circular dependencies. In response to these issues in application, a number of approximating algorithms have been proposed, but it remains to be seen whether these algorithms are effective given a large number of foragers with realistic characteristics. We implemented several algorithms approximating marginal value foraging in a large-scale avian foraging model and compared the results. We found that a novel reinforcement-learning algorithm that includes cost of travel is the most effective algorithm that most closely approximates marginal value foraging theory and recreates depletion patterns observed in empirical studies

Participar de la extensión en el LVM en clave nodocente

El presente trabajo se propone compartir la experiencia como integrantes nodocentes en uno de los Proyectos de Extensión que están llevándose a cabo actualmente en el Liceo “Víctor Mercante”.Liceo "Víctor Mercante

Wetland occupancy by duck broods in cropland-dominated landscapes of the United States Prairie Pothole Region

The Prairie Pothole Region (PPR) is globally important for breeding waterfowl but has been altered via wetland drainage and grassland conversion to accommodate agricultural land use. Thus, understanding the ecology of waterfowl in these highly modified landscapes is essential for their conservation. Brood occurrence is the cumulative outcome of key life-history events including pair formation and territory establishment, nest success, and early brood survival. We applied new technological advances in brood surveying methods to understand brood use of wetlands and how land use and wetland-specific factors influenced brood use of 413 wetlands in crop-dominated landscapes in the PPR of Iowa, Minnesota, North Dakota, and South Dakota, USA, during summers of 2018–2020. Dynamic occupancy models combining information from 2 visits throughout the year revealed no difference among the 4 states or between private and public lands, resulting in a region-wide annual wetland occupancy estimate of 0.41 (95% credible interval [CrI] = 0.26, 0.58). We assessed aquatic invertebrate forage availability, wetland and upland vegetation communities, and various water chemistry metrics in a subset (n = 225) of these wetlands to evaluate how landscape and wetland-specific factors influenced occupancy. The amount of grassland surrounding wetlands was the only variable to influence occupancy at a landscape scale, while wetland size, invertebrates, fish, and vegetation communities influenced occupancy at finer scales. Closer scrutiny of wetland area revealed occupancy was greater in small wetlands after controlling for total wetland area. Our results indicate the greatest constraint on brood occupancy across crop-dominated landscapes of the PPR in the United States was the occurrence of semipermanent wetlands suitable for brood rearing. Other factors, such as wetland vegetation or surrounding land use, had minor intervening influences on duck brood use and ducks were distributed invariant of wetland ownership or broad spatial processes occurring among states. These results demonstrated wetland conservation and restoration strategies are likely to yield gains in annual duck broods across this vast, altered, and highly modified landscape