Singing behaviour of ruby‐crowned kinglets Regulus calendula in relation to time‐of‐day, time‐of‐year and social context

2020 ◽  
Vol 51 (7) ◽  
Author(s):  
Mohammad Fahmy ◽  
David R. Wilson
Keyword(s):  
Social Context ◽  
Time Of Day ◽  
Time Of Year

Effect of time of day, time of year, and life history strategy on time budgeting in juvenile Atlantic salmon, Salmo salar

1999 ◽  
Vol 56 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
Sveinn K Valdimarsson ◽  
Neil B Metcalfe
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Life History Strategy ◽  
Time Of Day ◽  
Life History Strategies ◽  
Foraging Efficiency ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Time Of Year

Traditionally, behavioural studies on juvenile Atlantic salmon, Salmo salar, have been conducted during the day in summer. It is known that Atlantic salmon become nocturnal in winter, but very little is known about their behaviour at that time. Therefore, observations in a seminatural stream were carried out during the day and night, from February to June, comparing diel and seasonal differences in behaviour between fish adopting alternative life history strategies. The results showed a general trend for more activity in spring than in winter, and the fish were found to be foraging at surprisingly low light levels. There were differences in relative feeding rate between the life history strategies; the early migrant fish foraged mostly during the day whereas the delayed migrant fish did more foraging at night. There is some evidence that the early migrant fish made fewer feeding attempts over the winter, which is surprising, since they grow faster over that period. This suggests differences in foraging efficiency, which could contribute to the separation into these two life history strategies.

Analysis of an Instaneous Census Method for Heathland Birds

1983 ◽  
Vol 10 (3) ◽  
pp. 521 ◽  
Author(s):  
GH Pyke
Keyword(s):  
Frequency Distribution ◽  
Bird Species ◽  
Time Of Day ◽  
Vegetation Height ◽  
Time Of Year

Birds were censused from the top of a 2.5-m ladder positioned at the centre of circles of radius 20 m. Every 1 min the observer visually scanned one half of a circle, recording the identity of and the distance to every bird seen. This procedure was carried out for about eight scans and then repeated for the complementary semicircle. Birds tended to be repulsed from the observer and/or ladder. Consequently the census method cannot be used to estimate absolute densities. However, the frequency distribution of bird-observer distances was found to be independent of time of day, time of year, and bird species. The method can, therefore, be used at a particular location to compare different bird species and different times. Vegetation height affected the frequency distribution of bird-observer distances and so the method cannot provide accurate comparisons of bird densities in different areas. Fewer birds were seen per scan when the census was carried out 4-6 h after sunrise. The two observers in the study saw the same average number of birds per scan.

Xylem sap analysis for determining nutritional status of trees: Pseudotsugamenziesii

1985 ◽  
Vol 15 (2) ◽  
pp. 429-437 ◽  
Author(s):  
N. Stark ◽  
C. Spitzner ◽  
D. Essig
Keyword(s):  
Xylem Sap ◽  
Time Of Day ◽  
Tree Age ◽  
Poor Growth ◽  
Field Problem ◽  
Soil Extracts ◽  
Growth Site ◽  
Ion Concentrations ◽  
The Poor ◽  
Time Of Year

Xylem sap extraction of branches as a new field problem-solving technique in forestry, environmental pollution, and botany is described. The influence of extraction pressure, crown aspect, height into the crown, tree age, time of year and day, and soil chemistry on the ion concentrations in xylem sap are discussed. Xylem sap extraction with a pressure chamber provides a good indication of the nutrient status of a species if the trees are of similar age, and if they are sampled at the same aspect, crown height, time of day, time of year, and on the same soils. Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir), growing on nutrient-poor acid soils and moderately fertile alkaline soils showed significant differences in growth rate and ion concentrations in the xylem sap and soil. Trees on the faster growth site (< 12 rings/2.54 cm) had significantly more Ca, K, Mn, P, and N in the xylem sap. Trees on the poor growth site had high levels of Mg in the sap. Trees growing on the poor site which was also K deficient transpired more rapidly than those with faster growth. It is hypothesized that insufficient plant K could reduce the ability of the guard cells to control water loss. The stem water potential was slightly, but not significantly, higher on the poor growth site. Although there is no proof that the deficient ions are the cause of poor growth, they are suspect, given the similar water availability on the two sites. The concept of nutrient supplying potential of a tree, or its ability to supply its needles and meristems with water and nutrients is discussed. Distilled water soil extracts and foliar analyses would not have reflected the same ion relationships (deficiencies or excesses) that are evident in the xylem sap. Evidence for the factors controlling growth in these stands is being sought through fertilizer tests.

scholarly journals Should it matter when we record? Time of year and time of day as factors influencing frontal EEG asymmetry

2012 ◽  
Vol 91 (2) ◽  
pp. 283-291 ◽  
Author(s):  
Jamie R. Velo ◽  
Jennifer L. Stewart ◽  
Brant P. Hasler ◽  
David N. Towers ◽  
John J.B. Allen
Keyword(s):  
Time Of Day ◽  
Eeg Asymmetry ◽  
Frontal Eeg Asymmetry ◽  
Record Time ◽  
Factors Influencing ◽  
Time Of Year

scholarly journals Solar Dish Field System Model for Spacing Optimization

2007 ◽  
Author(s):  
John Igo ◽  
Charles E. Andraka
Keyword(s):  
Capital Investment ◽  
Meteorological Data ◽  
Field Performance ◽  
Energy Performance ◽  
Time Of Day ◽  
Plant Production ◽  
Electrical Grid ◽  
Time Of Year ◽  
The Individual ◽  
The Impact

Dish Stirling power generation systems have been identified by DOE, Sandia National Laboratories, and Stirling Energy Systems (SES) as having the capability of delivering utility-scale renewable energy to the nation’s electrical grid. SES has proposed large plants, 20,000 units or more (0.5 GW rated power) in one place, in order to rapidly ramp up production automation. With the large capital investment needed in such a plant it becomes critical to optimize the system at the field level, as well as at the individual unit level. In this new software model, we provide a tool that predicts the annual and monthly energy performance of a field of dishes, in particular taking into account the impact of dish-to-dish shading on the energy and revenue streams. The Excel-based model goes beyond prior models in that it incorporates the true dish shape (flexible to accommodate many dish designs), multiple-row shading, and a revenue stream model that incorporates time-of-day and time-of-year pricing. This last feature is critical to understanding key shading tradeoffs on a financial basis. The model uses TMY or 15-minute meteorological data for the selected location. It can incorporate local ground slope across the plant, as well as stagger between the rows of dish systems. It also incorporates field-edge effects, which can be significant on smaller plants. It also incorporates factors for measured degraded performance due to shading. This tool provides one aspect of the decision process for fielding many systems, and must be combined with land costs, copper layout and costs, and O&M predictions (driving distance issues) in order to optimize the loss of power due to shading against the added expense of a larger spatial array. Considering only the energy and revenue stream, the model indicates that a rectangular, unstaggered field layout maximizes field performance. We also found that recognizing and accounting for true performance degradation due to shading significantly impacts plant production, compared with prior modeling attempts.

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