229 research outputs found
American Kestrel Migration: Insights and Challenges from Tracking Individuals Across the Annual Cycle
Natural variation in migratory strategies across the range of the American Kestrel (Falco sparverius) creates a unique opportunity for comparative research of annual cycles. However, it can be logistically and technically challenging to track such a small but highly mobile species. We tagged American Kestrels with light-level geolocators or satellite transmitters with the aim of estimating migration timing and connectivity, and we monitored a subset of satellite-tagged individuals during the breeding season to assess transmitter function and wear. We recovered geolocators from six of 49 (12%) tagged individuals. One geolocator-tagged individual migrated approximately 1235 km from its Idaho breeding grounds to New Mexico near the Arizona border for the winter and returned to Idaho the following spring. The other five recaptured individuals remained near (\u3c 200 km) the breeding grounds year-round. The low reliability of recovery and low precision of locations suggested major limitations of using geolocators to track this species. Most satellite transmitters (18 of 22, 82%) failed prior to migration, but one satellite-tagged individual migrated approximately 5945 km from Canada to Nicaragua, and three others transmitted ≥1 location during migration. Transmitters stopped functioning while on live individuals despite showing no visible damage and maintaining adequate battery levels. These results suggest further testing and development are needed before these recently developed tags are deployed again on American Kestrels. Both individuals with complete migration tracks showed evidence of short distance (250–350 km) post-breeding movements to southern stopover sites where they stayed 1–3 mo before migrating onward. Although sample sizes were small, migration patterns were consistent with latitudinal leap-frog patterns described in previous studies and revealed an interesting pattern of a prolonged post-breeding stopover before longer migration. Further, the migration track from Canada to Nicaragua represents the longest recorded migration path for this species
Spatially explicit model of wintering common loons: conservation implications
Common loons Gavia immer are a conservation concern in New England due to a variety of anthropogenic factors, yet little is known about biotic and abiotic environmental factors determining their wintering distribution and abundance in nearshore and offshore waters. The primary objective of this study was to develop a spatially explicit abundance model of wintering common loons in the maritime waters of southern New England (USA) that could inform decisions about offshore development. Aerial line-transect surveys were conducted throughout a 3800 km2 study area off the coast of Rhode Island during the winters of 2010–2011 and 2011–2012. A density surface model (DSM) approach was used to account for imperfect detection and incorporate spatially explicit environmental covariates. Common loon densities were greatest in watersdeep, with high chl a surface concentrations (\u3e2 mg m−3). The DSM predicted 5047 (95% CI = 3993−6379) common loons in the study area during winter, which suggests this region provides key habitat for this species in eastern North America. This study highlights important areas for common loons in the region, suggests key biotic (primary productivity as measured by long-term chl a surface concentrations) and abiotic covariates (water depth) driving the spatial distribution and abundance of common loons in southern New England, and identifies sites that should be considered for protection from offshore development, including offshore wind facilities
Constraining the degree of the dominant mode in QQ Vir
We present early results of the application of a method which uses multicolor
photometry and spectroscopy for \ell discrimination. This method has been
successfully applied to the pulsating hot subdwarf Balloon 090100001. Here we
apply the method to QQ Vir (PG1325+101). This star was observed
spectroscopically and photometrically in 2008. Details on spectroscopy can be
found in Telting et al. (2010) while photometry and preliminary results on \ell
discrimination are provided here. The main aim of this work was to compare the
value of the \ell parameter derived for the main mode in QQ Vir to previously
published values derived by using different methods.Comment: Proceedings of The Fourth Meeting on Hot Subdwarf Stars and Related
Objects held in China, 20-24 July 2009. Accepted for publication in
Astrophysics and Space Scienc
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No maintenance -- no energy efficiency
Field investigations illustrate that it is not realistic to expect new high-tech equipment to function for a full life expectancy at high efficiency without significant operations and maintenance (O&M). A simple walk through inspection of most buildings reveals extensive equipment that is being operated on manual override, is incorrectly adjusted and operating inefficiently, or is simply inoperative. This point is illustrated with two examples at Robins Air Force Base, Georgia. The first describes development of a comprehensive, base-wide, steam trap maintenance program. The second describes a measured evaluation from a typical office building. The objective of both examples was to assess the importance of proper O&M. The proposed ``O&M First`` philosophy will result in more efficient building HVAC operation, provide improved services to the building occupants, and reduce energy consumption and unscheduled equipment repair/replacement. Implementation of a comprehensive O&M program will result in a 15--25% energy savings. The O&M foundation that is established will allow other energy conservation activities such is demand side management or energy management and control systems, to achieve and maintain their expected energy savings
Rapid environmental degradation in a subarctic ecosystem influences resource use of a keystone avian herbivore
Summary 1. Environmental degradation can change resource use strategies of animals and thereby affect survival and fitness. Arctic herbivores may be especially susceptible to the effects of such environmental change because their rapid growth rates demand high-quality forage, which may be limited as environmental conditions deteriorate. We studied the consequences of a trophic cascade, driven by Lesser Snow Goose (Chen caerulescens caerulescens) overgrazing on the south-west coast of Hudson Bay, Canada, which has caused tidal marsh (TM) degradation and the reduction in highquality forage plants, on gosling growth and resource use. 2. We compared resource use and body size of goslings that inhabited tidal and freshwater marsh (FM) to determine how current foraging strategies influence growth and to test the hypothesis that during early growth goslings require and so consume high-quality TM plants, but that during later growth they may switch to foraging in lower-quality FM. 3. To investigate gosling resource use throughout growth, we measured once a week for 28 days the body size of goslings as well as stable isotope ratios (d C) in multiple tissues of goslings that were collected from both TM and nearby FM. We also measured the stable isotope ratios in forage plants sampled along transects and from gosling foreguts. We used an isotopemixing model to determine the contribution of FM plants to gosling tissues. 4. Contrary to the proposed hypothesis, goslings inhabiting FM or TM primarily consumed FM plants during early growth. Furthermore, goslings that foraged extensively in FM had similar growth rates and grew to a similar size and body mass, as goslings that foraged in the degraded TM. However, goslings that currently inhabit freshwater or TM were significantly smaller than goslings that inhabited TM in the 1980s prior to habitat degradation. 5. Consequences of smaller overall body size include decreased survival and fecundity for arcticnesting geese. The ability of phenotypically plastic responses to sustain persistence is limited by reaction norms and the extent of environmental change. Current research is assessing whether those limits have been reached in this system
Phenology Effects on Productivity and Hatching-Asynchrony of American Kestrels (\u3cem\u3eFalco sparverius\u3c/em\u3e) Across a Continent
Optimal reproductive performance occurs when birds time reproduction to coincide with peak food availability. Deviation from optimal timing, or mismatch, can affect productivity, though birds may mediate some mismatch effects by altering their incubation behavior. We studied the consequences of nesting timing (i.e., clutch initiation relative to an index of spring start) on productivity across the breeding range of American kestrels (Falco sparverius) in the United States and southern Canada, and associations between nesting timing, incubation behavior, and hatching asynchrony. We used observations from long-term nest box monitoring, remote trail cameras, and community-scientist-based programs to obtain data on clutch initiation, productivity, incubation, and hatching synchrony. Kestrels that initiated clutches after the extended spring index (SI-x, start of spring estimate) had higher rates of nest failure and fewer nestlings than earlier nesters, and effects of nesting timing on productivity were strongest in the Northeast. In contrast, kestrels in the Southwest experienced a more gradual decline in productivity across the season. Spatial effects may be the result of regional differences in growing seasons and temporal nesting windows (duration of nesting season). Specifically, resource availability in the Northeast was highly peaked during the breeding season, potentially resulting in shorter nesting windows. Conversely, resource curves were more prolonged in the Southwest, and growing seasons are becoming longer with climate change, potentially resulting in longer nesting windows. We found an inverse relationship between nesting timing and the onset of male incubation. Males from breeding pairs that initiated clutches after SI-x began incubation sooner than males from breeding pairs that initiated clutches before SI-x. Early-onset of male incubation was positively associated with hatching asynchrony, creating increased age variation in developing young. In sum, nesting phenology relative to the SI-x has consequences for American kestrels’ productivity, and these consequences vary across space. The early onset of incubation may act as a potential adaptive behavior to advance the average hatch date and spread out energetic demands. Given the effects of nesting timing on productivity, kestrels are likely to be sensitive to climate-driven advances in growing seasons and vulnerable to phenological mismatch, particularly in the Northeast
Absolute dimensions of the unevolved B-type eclipsing binary GG Orionis
We present photometric observations in B and V as well as spectroscopic
observations of the detached, eccentric 6.6-day double-lined eclipsing binary
GG Ori, a member of the Orion OB1 association. Absolute dimensions of the
components, which are virtually identical, are determined to high accuracy
(better than 1% in the masses and better than 2% in the radii) for the purpose
of testing various aspects of theoretical modeling. We obtain M(A) = 2.342 +/-
0.016 solar masses and R(A) = 1.852 +/- 0.025 solar radii for the primary, and
M(B) = 2.338 +/- 0.017 solar masses and R(B) = 1.830 +/- 0.025 solar radii for
the secondary. The effective temperature of both stars is 9950 +/- 200 K,
corresponding to a spectral type of B9.5. GG Ori is very close to the ZAMS, and
comparison with current stellar evolution models gives ages of 65-82 Myr or 7.7
Myr depending on whether the system is considered to be burning hydrogen on the
main sequence or still in the final stages of pre-main sequence contraction. We
have detected apsidal motion in the binary at a rate of dw/dt = 0.00061 +/-
0.00025 degrees per cycle, corresponding to an apsidal period of U = 10700 +/-
4500 yr. A substantial fraction of this (approximately 70%) is due to the
contribution from General Relativity.Comment: To appear in The Astronomical Journal, December 200
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Cost-Effective Integration of Efficient Low-Lift Base Load Cooling Equipment
The long-term goal of DOE’s Commercial Buildings Integration subprogram is to develop cost-effective technologies and building practices that will enable the design and construction of net Zero Energy Buildings — commercial buildings that produce as much energy as they use on an annual basis — by 2025. To support this long-term goal, DOE further called for — as part of its FY07 Statement of Needs — the development by 2010 of “five cost-effective design technology option sets using highly efficient component technologies, integrated controls, improved construction practices, streamlined commissioning, maintenance and operating procedures that will make new and existing commercial buildings durable, healthy and safe for occupants.” In response, PNNL proposed and DOE funded a scoping study investigation of one such technology option set, low-lift cooling, that offers potentially exemplary HVAC energy performance relative to ASHRAE Standard 90.1-2004. The primary purpose of the scoping study was to estimate the national technical energy savings potential of this TOS
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