Unusual Behavior in Parental Care by a House Wren (Troglodytes aedon): Post Fledging Use of an Old Nest During Cold Nights

I report on the unusual behavior of an adult House Wren (Troglodytes aedon) leading recently fledged young back to the nest for two consecutive nights. The ambient temperature reached below 0°C during both nights. Despite disadvantages associated with remaining in the nest, this observation suggests that adult birds may assess trade-offs between perceived risks versus the benefits of engaging in other activities, in this case roosting communally for thermoregulation

Factors Associated with Flammulated Owl and Northern Saw-Whet Owl Occupancy in Southern Idaho

Spatially explicit models depicting species occupancy offer a useful conservation tool for land managers. Using occurrence data collected in 2009 and 2010 from the Boise National Forest, Idaho, we developed distribution models for Flammulated Owls (Psiloscops flammeolus) and Northern Saw-whet Owls (Aegolius acadicus) to explore associations between habitat factors and owl occupancy. We then spatially applied these models in a Geographic Information System. We considered land cover and topographic variables at three spatial scales: 0.4-km, 1-km, or 3-km-radius plots centered on point-count locations (n  =  150) with resolution of land covers at 30 m. Flammulated Owls occupied 27 (18%) point-count locations and occurred in areas with a higher proportion of Douglas-fir (Pseudotsuga menziesii) at the 0.4-km scale, less diverse land cover composition at the 1-km scale, and in south-facing aspects at the 3-km scale. Northern Saw-whet Owls occupied 45 (30%) point-count locations and were associated with relatively flat terrain at the 0.4-km scale that had larger proportions of non-forest land cover. At the 1-km and 3-km scales, Northern Saw-whet Owls occurred in areas with south-facing aspects having a higher proportion of ponderosa pine (Pinus ponderosa), respectively. Biologists and land managers interested in the conservation of Flammulated Owls and Northern Saw-whet Owls can use our approach to delineate habitats important for these owls or to help identify locations suitable for restoration

A Road Maintenance Management Information System for Counties and Cities

County Highway Departments in Indiana follow guidelines approved by the State Board of Accounts, mainly for highway resource accounting and not for maintenance activity costing. The existing Daily Work Report Form was modified to help maintenance activity costing with more precise reporting of road location, equipment and material use and also for storage on a microcomputer database. The Highway Extension and Research Project for Indiana Counties and Cities (HERPICC) at Purdue University tested the recommended procedures in a pilot project with White County Highway Department in Indiana, U.S.A.. A user-friendly program was developed using the R-Base 5000 database software for maintenance activity accounting and has been recommended for use by county highway and city street departments in Indiana. In addition, organizational requirements such as maintenance staff training, requirements for road inventory and road section demarcation, and special considerations for unpaved road maintenance activities such as dragging, grading, spot regraveling and the reporting required are described

Self-Regulation of Solar Coronal Heating Process via Collisionless Reconnection Condition

I propose a new paradigm for solar coronal heating viewed as a self-regulating process keeping the plasma marginally collisionless. The mechanism is based on the coupling between two effects. First, coronal density controls the plasma collisionality and hence the transition between the slow collisional Sweet-Parker and the fast collisionless reconnection regimes. In turn, coronal energy release leads to chromospheric evaporation, increasing the density and thus inhibiting subsequent reconnection of the newly-reconnected loops. As a result, statistically, the density fluctuates around some critical level, comparable to that observed in the corona. In the long run, coronal heating can be represented by repeating cycles of fast reconnection events (nano-flares), evaporation episodes, and long periods of slow magnetic stress build-up and radiative cooling of the coronal plasma.Comment: 4 pages; Phys. Rev. Lett., in pres

MOLT PATTERNS AND SEXING AND AGING CRITERIA FOR TEN SPECIES OF HIGH ELEVATION LANDBIRDS FROM SOUTHEASTERN PERU

Abstract ∙ Knowledge of molt patterns and their resulting plumages is useful for aging and sexing birds and, in mono‐ chromatic species, morphometric measurements can help to discern males from females. However, these data are largely undescribed for the majority of the world’s bird species, especially in the tropics. We sought to classify the molt strategy for 10 species of Neotropical passerines during their breeding seasons and considered whether a combination of wing chord, tail length and mass could be used to determine their sex. We used banding data from three years of mark‐recapture study at Wayqecha Biological Station (2900 m a.s.l.) along the east slope of the Andes in southeastern Peru to characterize molt and estimate morphological measurements. Each of the species exhibited a complete definitive prebasic molt and either a partial (nine species) or partial‐incomplete (one species) preformative molt, which we interpreted to be consistent with a complex basic molt strategy. For five of the 10 species, we found that wing, tail, and body mass measurements were useful in distinguishing between males and females. This study contributes to our understanding of tropical bird molt by providing previously undescribed aging and sexing criteria for some tropical landbirds common to high elevations of southern Peru.Resumen ∙ Patrones de muda y criterios para categorizar sexo y edad en diez especies de aves altoandinas en el sureste de Perú Los patrones de muda en la mayoría de las aves Neotropicales son poco conocidos y en especial se desconoce si las medidas corporales pueden ser usadas para determinar el sexo en especies sin dimorfismo sexual. En este trabajo clasificamos la estrategia de muda para 10 especies de paserinos Neotropicales y también exploramos si una combi‐ nación de medidas de longitud del ala, longitud de la cola y masa corporal pueden ser usadas para la determinación del sexo. Usamos datos de anillamiento de tres años de un estudio de recaptura en la Estación Biológica Wayqecha (2900 m s.n.m.) en el flanco oriental de los Andes al sureste de Perú. Cada especie exhibió una estrategia básica compleja de muda con una muda prebásica definitiva compleja, y una muda preformativa parcial (nueve especies) o parcial‐incompleta (uno especie). Para cinco de cada 10 especies, la combinación de medidas de la longitud del ala, la cola, y la masa corporal sirvieron para distinguir entre machos y hembras. Este estudio contribuye a la creciente literatura sobre los patrones de muda en aves tropicales y provee herramientas para clasificar la edad y el sexo de aves con plumaje sexualmente monocromático

A Model for Patchy Reconnection in Three Dimensions

We show, theoretically and via MHD simulations, how a short burst of reconnection localized in three dimensions on a one-dimensional current sheet creates a pair of reconnected flux tubes. We focus on the post-reconnection evolution of these flux tubes, studying their velocities and shapes. We find that slow-mode shocks propagate along these reconnected flux tubes, releasing magnetic energy as in steady-state Petschek reconnection. The geometry of these three-dimensional shocks, however, differs dramatically from the classical two-dimensional geometry. They propagate along the flux tube legs in four isolated fronts, whereas in the two-dimensional Petschek model, they form a continuous, stationary pair of V-shaped fronts. We find that the cross sections of these reconnected flux tubes appear as teardrop shaped bundles of flux propagating away from the reconnection site. Based on this, we argue that the descending coronal voids seen by Yohkoh SXT, LASCO, and TRACE are reconnected flux tubes descending from a flare site in the high corona, for example after a coronal mass ejection. In this model, these flux tubes would then settle into equilibrium in the low corona, forming an arcade of post-flare coronal loops.Comment: 27 pages plus 16 figure

Fast Collisionless Reconnection Condition and Self-Organization of Solar Coronal Heating

I propose that solar coronal heating is a self-regulating process that keeps the coronal plasma roughly marginally collisionless. The self-regulating mechanism is based on the interplay of two effects. First, plasma density controls coronal energy release via the transition between the slow collisional Sweet-Parker regime and the fast collisionless reconnection regime. This transition takes place when the Sweet--Parker layer becomes thinner than the characteristic collisionless reconnection scale. I present a simple criterion for this transition in terms of the upstream plasma density (n_e), the reconnecting (B_0) and guide (B_z) magnetic field components, and the global length (L) of the reconnection layer: L < 6.10^9 cm [n_e/(10^{10}/cm^3)]^(-3) (B_0/30G)^4 (B_0/B_z)^2. Next, coronal energy release by reconnection raises the ambient plasma density via chromospheric evaporation and this, in turn, temporarily inhibits subsequent reconnection involving the newly-reconnected loops. Over time, however, radiative cooling gradually lowers the density again below the critical value and fast reconnection again becomes possible. As a result, the density is highly inhomogeneous and intermittent but, statistically, does not deviate strongly from the critical value which is comparable with the observed coronal density. Thus, in the long run, the coronal heating process can be represented by repeating cycles that consist of fast reconnection events (i.e., nanoflares), followed by rapid evaporation episodes, followed by relatively long periods (1-hour) during which magnetic stresses build up and simultaneously the plasma cools down and precipitates.Comment: 17 pages, no figures; accepted to the Astrophysical Journal; replaced to match the accepted versio

Variable Shifts in the Autumn Migration Phenology of Soaring Birds in Southern Spain

While alteration of the migratory habits of birds is widely regarded as one of the most evident ecological effects of climate change, studies reporting shifts in migration phenology for long-lived, long-distance migrants have been few. Using time series of count data collected in southern Spain during autumn migration, we examined the magnitude and direction of phenological shifts for six common species of soaring birds. Many current methods for investigating phenological change rely on continuous data sets; however, these data may be unavailable for a variety of reasons. We used a cross-correlation analysis, which allowed us to compare recent data on the timing of migration from 1999–2011 to a historic data set collected during 1976–1977. The direction of phenological shifts for autumn migration was species-specific. White Storks Ciconia ciconia and Black Kites Milvus migrans appeared to have delayed passage, Black Storks Ciconia nigra and European Honey Buzzards Pernis apivorus have advanced their migratory timing, and we found no clear phenological change for Short-toed Eagles Circaetus gallicus or Booted Eagles Hieraaetus pennatus

Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model

The full kinetic dynamics of a perpendicular collisionless shock is studied by means of a one-dimensional electromagnetic full particle simulation. The present simulation domain is taken in the shock rest frame in contrast to the previous full particle simulations of shocks. Preliminary results show that the downstream state falls into a unique cyclic reformation state for a given set of upstream parameters through the self-consistent kinetic processes.Comment: 4 pages, 2 figures, published in "Earth, Planets and Space" (EPS), the paper with full resolution images is http://theo.phys.sci.hiroshima-u.ac.jp/~ryo/papers/shock_rest.pd

Diamagnetic Suppression of Component Magnetic Reconnection at the Magnetopause

We present particle-in-cell simulations of collisionless magnetic reconnection in a system (like the magnetopause) with a large density asymmetry across the current layer. In the presence of an ambient component of the magnetic field perpendicular to the reconnection plane the gradient creates a diamagnetic drift that advects the X-line with the electron diamagnetic velocity. When the relative drift between the ions and electrons is of the order the Alfven speed the large scale outflows from the X-line necessary for fast reconnection cannot develop and the reconnection is suppressed. We discuss how these effects vary with both the plasma beta and the shear angle of the reconnecting field and discuss observational evidence for diamagnetic stabilization at the magnetopause.Comment: 10 pages, 10 figures; accepted by JGR; agu2001.cls and agu.bst include