Behavioural thermoregulation in wintering black ducks: roosting and resting

1984 ◽  
Vol 62 (7) ◽  
pp. 1223-1226 ◽  
Author(s):  
Lynn M. Brodsky ◽  
Patrick J. Weatherhead
Keyword(s):  
Volume Ratio ◽  
Cold Weather ◽  
Energy Costs ◽  
The Sun ◽  
Behavioural Thermoregulation ◽  
Feeding Site ◽  
Convective Heat Loss ◽  
Increase Food Intake ◽  
Consequent Reduction ◽  
Foraging Time

Black ducks (Anas rubripes) wintering near Ottawa, Canada, used a variety of behaviours to reduce their energy costs. The roost site that they occupied provided greater protection from wind than the feeding site, with the consequent reduction in forced convective heat loss. Time spent at the feeding site (i.e., away from the roost) varied with temperature such that ducks maximized their time at the roost on the coldest days. This relationship was facilitated by the ducks' food supply (cracked corn replenished daily), which precluded extending foraging time to increase food intake in cold weather. At the roost ducks huddled in colder weather and adopted postures that reduced both the nonfeathered area exposed to the air and also the surface to volume ratio. The ducks preferentially faced toward the sun and into the wind, but when these were in opposite directions they faced the sun only when wind speed was low.

Behavioural Thermoregulation in the Freeze-Tolerant Arctic Caterpillar, Gynaephora Groenlandica

1988 ◽  
Vol 138 (1) ◽  
pp. 181-193 ◽  
Author(s):  
OLGA KUKAL ◽  
BERND HEINRICH ◽  
JOHN G. DUMAN
Keyword(s):  
Solar Radiation ◽  
Growth And Development ◽  
High Arctic ◽  
The Sun ◽  
Metabolic Rates ◽  
Behavioural Thermoregulation ◽  
Body Temperatures ◽  
Feeding Site ◽  
Freeze Tolerant ◽  
Gynaephora Groenlandica

Larvae of the high arctic caterpillar, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae) spent most (60 %) of their time orienting towards the sun (i.e. basking) and only 20% feeding, primarily near midday. Larvae usually basked after feeding, then either fed again or moved to a new feeding site. Basking larvae reached their highest body temperatures (Tb) of ≊30°C (≊20°C in excess of the ambient temperature) when surrounded by snow on a calm day in the midday sun. Setae significantly decreased larval cooling rates. Maximal metabolic rates were attained in basking larvae, but at body temperatures below 10°C oxygen uptake was greatly reduced. Our studies indicate that G. groenlandica larvae are behaviourally adapted to utilize available solar radiation for growth and development.

Calculating the periods of radio signal transmission between two spacecrafts through the Venus atmosphere in the problem of studying its composition

2019 ◽  
Author(s):  
K.S. Fedyaev ◽  
V.V. Koryanov ◽  
S.A. Bober ◽  
V.A. Zubko ◽  
A.A. Belyaev
Keyword(s):  
Radio Signal ◽  
Initial Conditions ◽  
Libration Point ◽  
Signal Transmission ◽  
Energy Costs ◽  
The Sun ◽  
Initial State ◽  
Collinear Libration Point ◽  
Small Spacecraft ◽  
Atmosphere Of Venus

The paper considers calculating the periods of radio signal transmission through the atmosphere of Venus between a small spacecraft placed in a limited orbit in the vicinity of the collinear libration point of the Sun-Venus system and a Venus orbiter. The problem arises in the framework of the project under discussion to study the atmosphere of Venus. The possibility of transfers of these spacecrafts to the required orbits under various initial conditions is also studied. The impulses required for transferring to the specified orbits at the selected initial state vector, the most suitable for solving this problem are calculated. The duration and the number of transmission periods depending on the location of one of the spacecrafts in a limited orbit in the vicinity of the libration point L1 or L2 of the Sun-Venus system are analyzed. The influence of the shape of the orbiter near-Venusian orbit on the character and duration of the periods of transmission through the atmosphere of Venus is investigated. It is concluded that the location of a small spacecraft in a limited orbit in the vicinity of the L1 libration point of the Sun-Venus system is more advantageous compared to L2 both in terms of the duration and the number of the transmission periods as well as terms of the necessary energy costs.

The heat balance of sheep standing in the sun

1957 ◽  
Vol 8 (3) ◽  
pp. 271 ◽  
Author(s):  
CHB Priestley
Keyword(s):  
Heat Balance ◽  
Heat Load ◽  
The Body ◽  
Wave Radiation ◽  
The Sun ◽  
Convective Heat Loss ◽  
Radiation Exchange ◽  
Long Wave ◽  
The Heat Balance ◽  
Long Wave Radiation

An extension is made of Lee's (1950) original discussion of the heat balance of sheep exposed to a tropical sun. Methods are given for calculating the two quantities, convective heat loss and long-wave radiation exchange, which automatically compensate to a large extent for the added heat load. There appear to be advantages in distinguishing between the heat balance of the fleece and that of the body of the sheep, and this provides a method of estimating the heat conducted to the body as a consequence of the insolation.

scholarly journals Shorebird feeding specialists differ in how environmental conditions alter their foraging time

2019 ◽  
Vol 31 (2) ◽  
pp. 371-382 ◽  
Author(s):  
Henk-Jan van der Kolk ◽  
Bruno J Ens ◽  
Kees Oosterbeek ◽  
Willem Bouten ◽  
Andrew M Allen ◽  
...  
Keyword(s):  
Environmental Change ◽  
Environmental Conditions ◽  
Individual Variation ◽  
Water Levels ◽  
Cold Weather ◽  
Accelerometer Data ◽  
Tidal Period ◽  
Heterogeneous Populations ◽  
Feeding Specialization ◽  
Foraging Time

Abstract Feeding specialization is a common cause of individual variation. Fitness payoffs of specialization vary with environmental conditions, but the underlying behavioral mechanisms are poorly understood. Such mechanistic knowledge, however, is crucial to reliably predict responses of heterogeneous populations to environmental change. We quantified spatiotemporal allocation of foraging behavior in wintering Eurasian oystercatchers (Haematopus ostralegus), a species in which feeding specialization can be inferred from bill shape. We combined global positioning system (GPS) and accelerometer data to quantify foraging time of 64 individuals for every tidal period in one or two winter seasons. Individuals varied widely in foraging time (3.7–6.5 h per tidal period) and individuals that spend more time foraging had lower inferred survival. Feeding specialization appeared a major determinant of individual variation in foraging time and its spatiotemporal allocation. Visually hunting worm specialists foraged more during day time and complemented intertidal foraging with grassland foraging when the exposure of intertidal flats was limited and nights were well illuminated. Shellfish specialists increased total foraging time in cold weather, whereas foraging time of worm specialists decreased as frosty grasslands became inaccessible. Our results imply that worm specialists may be most sensitive to cold snaps and daytime disturbance, whereas shellfish specialists are most sensitive to high water levels. These behavioral responses can be implemented in population models to predict the vulnerability of heterogeneous populations to environmental change and, thereby, provide a shortcut to long-term population studies that require fitness data across many years and conditions to make similar projections.

scholarly journals Foraging and Territory Economics of Sexually Dimorphic Purple-Throated Caribs (Eulampis Jugularis) on Three Heliconia Morphs

The Auk ◽  
2005 ◽  
Vol 122 (1) ◽  
pp. 187-204 ◽  
Author(s):  
Ethan J. Temeles ◽  
Robin S. Goldman ◽  
Alexei U. Kudla
Keyword(s):  
Lower Cost ◽  
Energy Costs ◽  
Sexually Dimorphic ◽  
Costs And Benefits ◽  
Energy Demands ◽  
Males And Females ◽  
Relative Gains ◽  
Time And Energy ◽  
Territorial Bird ◽  
Foraging Time

Abstract We observed territorial Purple-throated Caribs (Eulampis jugularis) on three Heliconia morphs (H. caribaea and the red-green and green morphs of H. bihai) on the island of St. Lucia, West Indies, to examine how calculated costs and benefits compared with observed patterns of Heliconia use. Across the three years of our study, H. caribaea territories defended by Purple-throated Carib males were significantly smaller in area and had higher densities of flowers than red-green H. bihai territories, and both kinds of Heliconia territories defended by males were smaller and had higher densities of flowers than the green H. bihai territory maintained by a female. In the period (0630 to 1400 hours) during which birds maintained territories, total maintenance costs were more than met by energy obtained from territories, but only 2 of 13 territories provided sufficient nectar to meet birds' energy requirements for 24 h. Birds supplemented their energy intake from Heliconia territories by foraging at flowers in the rainforest canopy, and the percentage of time a territorial bird spent foraging in the canopy was inversely correlated with energy production on its Heliconia territory. The smaller territory areas and higher flower densities of H. caribaea territories lowered males' foraging time and energy costs per flower on H. caribaea as compared with red-green H. bihai territories, theoretically allowing them to meet their energy demands in less time and at lower cost. Males' estimated foraging time and energy costs were greatest at the green morph of H. bihai; compared with females, they would save a higher proportion of time and energy by foraging at H. caribaea and the red-green morph of H. bihai. That asymmetry between males and females in relative gains from foraging at each of the three Heliconia morphs may further reinforce resource partitioning between them, in addition to differences in size and fighting abilities. Economía de Forrajeo y Territorialidad en la Especie Sexualmente Dimórfica Eulampis jugularis en Tres Formas de Heliconia

scholarly journals Decreased Sun’s activity will lead to a small ice age

2019 ◽  
pp. 73-76
Keyword(s):  
Climate Warming ◽  
Point Of View ◽  
Ice Age ◽  
Cold Weather ◽  
The Sun ◽  
Global Cooling ◽  
The World ◽  
Earth’S Climate

Due to the cold weather in 2014 and 2018-2019, millions of people around the world began to pay attention to the problem of «global cooling». In our country this problem has become known thanks to the publications of an article of physicist H. Abdussamatov in «Science and Life» (2009) and an interview with an English Professor of Mathematics V. Zharkova in a popular Russian newspaper «Komsomolskaya Pravda» (2018). During the preparation of the materials, we talked with many climate researchers in Russia and abroad, and we met some unanimous opinions based on the firm belief that climate warming will occur. The point of view of «climate warming» is so widespread that it seems a self-evident truth, it is unequivocal and does not need special evidence, and any attempt to challenge it may seem a hopeless effort. But Russian physicist H. Abdussamatov and English Professor of Mathematics V. Zharkova firmly claim the onset of global cooling in the middle of this century. We asked them to tell us about the latest results of their research. The Sun determines the Earth’s climate

scholarly journals Anthropogenic heat release in the atmosphere of Belgrade

2002 ◽  
Vol 82 (2) ◽  
pp. 55-66
Author(s):  
Goran Andjelkovic
Keyword(s):  
Global Warming ◽  
Heat Release ◽  
Air Temperature ◽  
Anthropogenic Heat ◽  
Anthropogenic Sources ◽  
Cold Weather ◽  
The Sun ◽  
Heat Island ◽  
Main Factors ◽  
Quantity Of Heat

During last few decades the phenomenon of global warming up of the atmosphere is discovered. It is also concluded that the climate in cities changes, the main result of what is the higher air temperature, the heat island within the places with cold weather. This happens also in Belgrade. There are many reasons for this phenomenon, but the anthropogenic production of energy is considered to be one of the main factors for the rise of temperature. The aim of this work is to define anthropogenic sources of heat in Belgrade and to reckon the quantity of heat they emit as additional sources in relation to the sun.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

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